Talk:Supernova/Archive 3

Atmosphere Fire
If a ray of energy from a supernova (from lack of a better term) hit Earth, wouldn't it's atmosphere set on fire? I don't remember reading that in the article, but that's what a friend told me. --BrandiAlwaysSmiles (talk) 18:13, 7 April 2010 (UTC)


 * There are some potential negative effects from a nearby supernova. (See Near-Earth supernova.) But I'm not sure I'd describe them as setting the atmosphere on fire, unless you count the chemical conversion of some nitrogen into nitrogen oxide.&mdash;RJH (talk) 18:39, 7 April 2010 (UTC)


 * "Setting the atmosphere on fire" is a doomsday scenario that was popular in the early to mid 20th century. The idea was that it might be possible for some form of runaway chemical reaction to consume most of the atmosphere if enough energy was dumped in to start it. As far as I know, this was never seriously proposed by scientists, and shouldn't actually be possible according to our present knowledge of the atmosphere (the atmosphere is already roughly at chemical equilibrium with itself). --Christopher Thomas (talk) 19:01, 7 April 2010 (UTC)

Photodisintegration?
I have a problem with this passage:


 * The core collapses in on itself with velocities reaching 70,000 km/s (0.23c),[50] resulting in a rapid increase in temperature and density. The energy loss processes operating in the core cease to be in equilibrium. Through photodisintegration, gamma rays decompose iron into helium nuclei and free neutrons, absorbing energy, whilst electrons and protons merge via electron capture, producing neutrons and electron neutrinos which escape.

Let's see. These energetic gamma rays are produced by very high temperature in the core. This temperature (=energy) is produced by fusion reactions and by using up energy released by collapse.

Fusion reactions draw their energy from the fact that products of these reactions have mass deficit (part of mass becomes energy).

Since not all fusion-produced energy is retained as a temperature in the core (much of it was radiated into space over the millions of years), how in hell gamma rays have enough energy to "decompose iron into helium nuclei and free neutrons", basically *undoing* all this fusion? Where this energy came from, since it can't be all from fusion?

Is it provided by rapid collapse of the core? —Preceding unsigned comment added by 88.101.163.106 (talk) 04:35, 25 December 2008 (UTC)


 * Yes, the energy comes from the collapse, as does most of the energy in a core-collapse supernova.--Silpion (talk) 03:52, 24 April 2009 (UTC)

Next supernova
Do astronomers have any vague idea as to which star will go supernova next and when?--Just James 23:09, 9 October 2006 (GMT+10:00)


 * unfortunately for astronomers, astrophysics and astroparticle physics there is no known model able to predict which star or when a star will become a supernova, as far as I know... Tatonzolo 10:16, 12 October 2006 (UTC)


 * Very vaguely, candidates 'local' to us would include Rho Cassiopeiae, Betelgeuse , Antares , Eta Carinae , or even this Kitt Peak Downes star Vague here can mean sometime between now and the next 10000 years (except for the last listed). There is one possible predictor  The Yeti 19:57, 5 January 2007 (UTC)

Here is another (don't know how to add it to the main article: HD 49798 http://spacespin.org/article.php/90905-xmm-newton-uncovers-celestial —Preceding unsigned comment added by 75.33.37.133 (talk) 17:41, 5 September 2009 (UTC)


 * don't expect to point your telescope to the sky and observe one, like an ecclipse or a planet or something. Sorry, we're not there yet Aax.nox 13:18, 1 August 2007 (UTC)

Convection interval for type Ia
The paper titled On the C/O Enrichment of Novae Ejecta gives a time scale of 103 years for the period between the onset of "envelope convection" and the runaway. A second paper On Heavy Element Enrichment in Classical Novae lists 6.9 &times; 104 years for one of the three scenarios. Am I reading this at all correctly? These values appear to be 1-2 orders of magnitude larger than the 100 years listed in this article. Is there a better reference for that result? Thanks! &mdash; RJH (talk) 22:24, 27 November 2006 (UTC)
 * The Hillebrandt/Niemeyer 2000 paper gives an estimate of ~1000 years, so I used that for now. &mdash; RJH (talk) 18:36, 1 january 2012 (UTC)

Asymmetry
I added a section on supernova asymmetry, based on the various references I could dig up. (Induced in part by a recent Sky&Telescope article.) But it would be appreciated if the content could be reviewed by an expert on the subject. Thank you! &mdash; RJH (talk) 20:37, 11 December 2006 (UTC)

It would be good to clarify that the first paragraph is in reference to massive star collapse -- eg, Type II supernovae. Recent theoretical work on Type Ia favors asymmetric explosions -- the initial flame bubbles carry buoyancy and can lead to a significantly off-centered explosion, as is the case in the Gravitationally Confined Detonation (GCD) scenario.

Rtfisher (talk) 22:14, 14 December 2009 (UTC)
 * Good point. I clarified the text. Thanks.&mdash;RJH (talk) 22:44, 14 December 2009 (UTC)

Article length & summary style
This article is becoming quite long and likely needs to have some material spun off into daughter articles, per WP:SS. As candidates I was thinking of having "Type Ia supernova" and "Type II supernova" sub-pages, with shorter summaries on the main Supernova page. Doing so will provide room for more details coverage of those sub-types. Does anybody find this objectionable? &mdash; RJH (talk) 23:37, 18 December 2006 (UTC)
 * Good idea. If I find some time, I'll help. Nick Mks 19:10, 23 December 2006 (UTC)
 * I was waiting to see how the FAC would resolve before proceding. Likely it can be spun out at a later date when more detail needs to be added. Thanks. &mdash; RJH (talk) 18:47, 8 February 2007 (UTC)


 * I don't think the article is too long. The amount of readable prose is fine.  If you are using the byte size (currently 85K), that isn't a good measure because of how much space is taken up by the citations.  The citations don't count towards the Article size "readable prose". The Mad Genius 16:00, 19 March 2007 (UTC)


 * Okay. In the future, though, we may still want to add separate articles on the supernovae class if more depth is needed. &mdash; RJH (talk) 18:17, 19 March 2007 (UTC)


 * Yes, it can always be split out if it becomes necessary. I was just making the point that the size of the current article is fine. The Mad Genius 01:45, 20 March 2007 (UTC)


 * I understood your point, as I indicated by the word "Okay". Thanks. &mdash; RJH (talk) 14:44, 21 March 2007 (UTC)

Images
Doesn't the figure that appears at the beginning of the Type II section have Oxygen and Neon switched?
 * No I believe it's correct. See Image talk:Evolved star fusion shells.png. &mdash; RJH (talk) 14:29, 9 July 2007 (UTC)

The non-English language editions of this article include some attractive graphics that could potentially be used here.

These light curves are available from the Spanish language page:
 * http://es.wikipedia.org/wiki/Imagen:SNIacurva.png
 * http://es.wikipedia.org/wiki/Imagen:SNIIcurva.png

The German page also has a detailed chart of type Ia supernovae:
 * http://de.wikipedia.org/wiki/Bild:SNtypIa.jpg

However I'm somewhat doubtful of licensing of the later page. I found a copy on a NASA site at one time, but the image also credited the author so it's not clear that the illustration is in the public domain. &mdash; RJH (talk) 21:34, 6 January 2007 (UTC)


 * Done. &mdash; RJH (talk) 18:00, 16 January 2007 (UTC)


 * The light curve image is a bit dubious, why have an axis scaled in terms of solar units and not have any numbers on it at all, it seems very pointless, it should just be in terms of L. —Preceding unsigned comment added by 80.235.132.32 (talk) 09:34, 31 January 2008 (UTC)

I'm having a heck of a time trying to upload a photo file into the Supernova entry in the Type I sub-category. I've never done this before, and started at "how to upload a file into an article" - but then ran into all kinds of very confusing instructions after I'd uploaded it. So I started all over and went through the procedure for uploading a federal government file (NASA). That was successful - but then I ran into the first file I'd uploaded which is now a duplicate that I can't seem to delete. The And now I'm told one or the other of the identical files will be speedy-deleted, although I have provided the copyright info -which seems to have disappeared after first having appeared when I clicked on the photo for an enlarged version - the URL for the photo is http://www.nasa.gov/centers/goddard/news/topstory/2008/swift_supernova.html. The instructions are needlessly confusing for a newbie, with all kinds of caveats and surprise requirements. All I know is that the file is legitimate and in the public domain, and is a worthy and very timely contribution to the article on Supernovas. This has taken me quite a long time and I don't know what to do next. I hope someone who knows what they're doing can straighten it all out for me. It's late and my brain hurts. Thanks very much. Wlegro (talk) 05:48, 22 May 2008 (UTC)
 * The other problem with the picture in the article is that it doesn't include the identifying numbers showing where the two supernovae are in the right-hand photo. This is probably because I clicked on that photo on the NASA site to enlarge it and then uploaded that - but I didn't notice at the time that the enlargement didn't include the identifiers while the thumb does. I gave the URL for the photo in my first note above - if anyone wants to do it properly it would help the readers to see where in the galaxy 2008D is (in the right-side photo) to compare it to the exploding star on the left. Argh. And I just noticed this is a gold star article. Or was. Wlegro (talk) 06:22, 22 May 2008 (UTC)
 * Okay, first of all this isn't the place for complaints about the image upload process. If you are having difficulty following the instructions, try Help:Contents/Images and media. There should be a pull-down menu on the image upload page that allows you to select NASA. Secondly, if the image is from NASA, I suggest uploading it to the Commons rather than wikipedia. In this case it looks like a diplicate is already present, so I modified the Commons image to add the correct license template.&mdash;RJH (talk) 14:55, 22 May 2008 (UTC)
 * Well, thanks for whatever you did - did you also rewrite the caption so it wasn't so long? If so, thanks for that, too. The duplicate is my fault for not doing it right the first time, and I am unable to delete it. The problem now is that file link goes to the duplicate without the copyright - I don't know why since I uploaded the file onto Commons after I discovered the issue with copyright documentation, so I thought the link would go to the correct version. Now I've gotten a message on Commons that the copyright license isn't right though it's plainly in sight http://commons.wikimedia.org/wiki/Image:Supernova_2008D.jpg. - I'm told that I posted only a template, not a license. So I give up. It's taking too much of my time, sorry to say, and I find the instructions user-unfriendly.


 * As far as where to explain my problems goes, I posted these issues wherever it seemed logical to me. Wikipedia is very user-friendly when it comes to looking things up, but not when it comes to contributing more than text. Wlegro (talk) 16:36, 22 May 2008 (UTC)
 * Yes I did modify the caption slightly and added a pair of citations. I also added the image to the Type Ib and Ic supernovae page. If you have some general WP comments, you might start at one of the Village Pump forums on the Community Portal. Somebody should be able to direct you from there.&mdash;RJH (talk) 17:36, 22 May 2008 (UTC)
 * Thanks. The NASA image included the locations of the two supernovae in white text, which didn't accompany the photo on uploading.Wlegro (talk) 19:39, 22 May 2008 (UTC)

Removed statement

 * Large-scale, multi-dimensional computing simulations are being planned that will model supernovae explosions in much greater detail, which could help explain many of the observables. However, these simulations have not been able to be undertaken because computers are not yet powerful enough. To date, calculations have been made in both one and two dimensions.

This is incorrect. The Max Planck Group has been doing 3d supernova simulations for some time, as has Mezzacappa et. al at Oak Ridge. The problem with 3-d simulations is that there is a computational tradeoff between modelling the hydro and the neutrino simulations.

Roadrunner 22:09, 16 March 2007 (UTC)


 * That paragraph was bound to get outdated at some point. Thanks. &mdash; RJH (talk) 16:21, 17 March 2007 (UTC)

Unsourced revisions
The following statements have been added to the article which I believe should have some type of published reference:


 * The neutrinos escape from the core, carrying away energy and further accelerating the collapse, which proceeds over a timescale of one-tenth a second.
 * More recent models have invokes a combination of asymmetry or magnetic fields to attempt to produce an explosion.
 * However, the lack of a good model to connect the pre-explosion star with the post-explosion has left many open questions, such as the exactly which stars will form neutron stars and which ones will form black holes, and statistical production rates of these objects, the role that supernova play in the creation of r-process elements.

Any suggestions? Thank you. &mdash; RJH (talk) 16:18, 17 March 2007 (UTC)


 * These have not been sourced. I stripped them out so that the page can retain it's FA rating. If some references turn up, these can always be added back in. &mdash; RJH (talk) 18:11, 29 April 2007 (UTC)

Time
I heard that if a star went supernova and it was 7 light years away, it would be 7 years til we would notice that it went supernova. Is that true?68.110.232.148 20:40, 18 March 2007 (UTC)


 * Yes. Light from the supernova travels at the speed of light. --Christopher Thomas 21:21, 18 March 2007 (UTC)

Yes it is true! Some more facts are if it is a number of light years that is how many light years it would take for us to see. Not only that (correct me if im wrong) but that is true for any thing. That is why astronomers are trying to look deeper and deeper in to space because if they do that they can see into the past. So if they look ^ billion years in to the past they see the big bang. —The preceding unsigned comment was added by 64.75.158.145 (talk • contribs).

SN2006gy
There are a few recent papers on SN2006gy, the most luminous supernova yet observed. In one paper by Smith et al, it is proposed that SN2006gy came from an LBV progenitor similar to Eta Carinae. In this paper, they propose that SN2006gy's extreme luminosity resulted from a Pair-instability supernova, i.e. one where a black hole is not formed and all the mass from the stellar explosion is returned to the interstellar medium. It can occur because of the creation/annihilation of electron-positron pairs that prevent collapse into a black hole according to http://astro.berkeley.edu/~soffner/imgsf8.html. This type of SN has extremely important implications for the early universe. However, my understanding of this SN type is limited to what I've just said. I think it's important enough to include on this page, but is there an expert who could add some details? --Keflavich 02:46, 29 April 2007 (UTC)
 * This page is already pretty bloated, so I'm not sure that every corner case needs to be included. Perhaps SN2006gy should have it's own page first so that the details can be clarified? &mdash; RJH (talk) 18:04, 29 April 2007 (UTC)


 * Looks like the topic now has it's own page. I've merged the SN2006gy entry on this article to the more appropriate history of supernova observation page. Thanks. &mdash; RJH (talk) 21:24, 8 May 2007 (UTC)


 * That's reasonable, but I still think there needs to be a section on pair-instability supernovae. I'm going to copy the very brief section from the sn2006gy article and make a new pair-instability article, but it will need work. --Keflavich 22:53, 8 May 2007 (UTC)


 * Okay the page has been thinned down now. Perhaps we should have a brief "Trigger mechanisms" sub-section just before the "Core collapse" discussion? (I.e. covering (1) exceeding Chandrasekhar limit; (2) pair-instability and (3) photo-disintegration.) &mdash; RJH (talk) 15:28, 17 May 2007 (UTC)


 * It would seem SN2006gy has to some extent rewritten the rule book. Despite being a type II is peak brightness was at least 10 times higher than any other known supernova and the bightness was sustained for a far greater time than is usual. Even now, many months after discovery, it is still putting out roughly the same energy as the peak energy output of the second most powerful supernova ever observed. It is postulated that the massive ammounts of energy needed to fuel this outburst came from matter/antimatter anihilation, driven by gamma rays. I'd be interested to know the current estimates for the ammount of energy released in this event - it may even be in the solar mass range. --LiamE 21:26, 14 May 2007 (UTC)

Forked articles / references
As was discussed earlier, the content of the Type Ia material has been spun off into a separate main article. It has been replaced with a relatively brief summary. This should help reduce the size of this article, which is well over the recommended length. &mdash; RJH (talk) 18:50, 30 April 2007 (UTC)
 * The same has been done with the Type II material. Both articles are now at good article status. There should be plenty of room for expansion on those sub-pages. (Hint. ;-) &mdash; RJH (talk) 17:11, 5 June 2007 (UTC)
 * Is there anyway of spinning the references off or compacting them ? As they take about a third of the page now! The Yeti 02:21, 8 June 2007 (UTC)
 * The references are required for the Featured Article status of this article. They are already in small font. Besides, a decent set of references may be useful for somebody who wants to study the topic further. &mdash; RJH (talk) 15:54, 8 June 2007 (UTC)
 * I'm not on about removing them, and I understand their importance. It was more that is there some way in Wikipedia to hive them off onto another page ? Or hiding them as a default, unless a user wants to open them ? The Yeti 23:34, 11 June 2007 (UTC)
 * The ArticleHistory template at the top of this talk page uses a compaction mechanism. (The hide/show link.) So something like that could probably be configured into the reference templates, if you can get consensus. &mdash; RJH (talk) 15:30, 12 June 2007 (UTC)
 * Seems this is something that'll have to be looked at by the powers that be, as, particularly for scientific articles, the references can run as long as the main part of the article. However, its beyond my capabilities to create your suggestion, nor do I know where to raise this. Why isn't there a Wikipedia for Wikipedia ?!! Or a search box solely for Wikipedian terminology - the hours I waste trying to find a WP: or the right discussion page in order to see how something is done or to clarify/query something ...! The Yeti 01:51, 13 June 2007 (UTC)
 * When I don't know where else to turn, I usually start with the village pump. In this case, however, you could also add a comment to the Template talk:Reflist page. But you won't necessarily get agreement. &mdash; RJH (talk) 16:32, 13 June 2007 (UTC)

Red giants and Supernova Ia
The second paragraph in the section on Supernova Ia states that accretion from a red giant on a white dwarf is resposible for the explosion. This claim is not supported by references and appears to be wrong. To my knowledge there is currently no consensus regarding progenerators of this type of supernova. They can be: WD+WD merges; accretion from MS stars, helium WDs, sdB stars etc. In fact, many supersoft X-ray source, which are also probable ancestors of Ia supernovas, contain MS stars and heavy WDs (~1.37 solar). So this paragraph should be seriously modified.Ruslik 08:11, 17 May 2007 (UTC)
 * The Type Ia supernova page covers alternate mechanisms in the Type_Ia_supernova section, although it appears incomplete. This page just has a summary-style description of the most likely mechanism. &mdash; RJH (talk) 14:57, 17 May 2007 (UTC)


 * The mechanism involving red giants doesn't appear to be the most likely from peer reviewed literature.Ruslik 07:05, 18 May 2007 (UTC)
 * So how accurate is this SAO page? The literature I saw didn't seem to favor the double-degenerate model listed. Perhaps this wikipedia article should just make brief mentions of the various favored progenitor models? &mdash; RJH (talk) 16:40, 18 May 2007 (UTC)
 * The page is as accurate as it states that 'at least some SNIa are the result of accretion from a giant star'. However the double-degenerate model hasn't been disapproved, it's just less favoured now and many scientist continue to pursue it . In the single degenerate model different stars can be secondaries: helium WDs(the latter reference has an especially good scheme of possible channels leading to SNIa explosions), subdwarf B (sdB) stars, MS stars (some supersoft X-ray sources and U Sco type recurrent novae). In fact in many published  works red giants are disfavoured as possible secondaries in SNIa progenirators . The recent SNIIa events SN 2002ic and 2006GY can be aslo explained without red giants using so called I+1/2 model or in DD model . Since there is no consensus regarding the model of SNIa (except that it probably results from an explosion of a carbon oxygen WD that managed somehow to acquire mass equal to CS limit), the wikipedia article should only make brief mentions of the various progenitor models without going into details (with appropriate referecnes).Ruslik 11:56, 20 May 2007 (UTC)
 * I didn't want to discard the red giant-white dwarf example because it is commonly given on many web sites. But I rearranged the text somewhat to allow for other possibilities. Thanks. &mdash; RJH (talk) 18:42, 20 May 2007 (UTC)
 * The current edition is good. However it should be mentioned that the white dwarf need to have carbon oxygen composition otherwise (O Ne Mg) it will collapse into a NS. Also the energy of the explosion is overestimated. Assuming the mass of WD 1.4 solar, composition 50% carbon (and 50% oxygen) and 100% conversion into Fe one obtains 2.5 J (this corresponds to ~0.8 Mev per nucleon). The real value is 1-2 J. Ruslik 07:39, 21 May 2007 (UTC)
 * Done. Thank you. &mdash; RJH (talk) 15:56, 12 June 2007 (UTC)

Correct spelling
Is it supernova or supernovae? at the beginning of the article it says supernova but after that in most of the section it says supernovae which one is the correct one? I didn't want to correct it because it appears a supernovae in most of the article

Amoscare 08:02, 17 June 2007 (UTC)Amoscare
 * Supernovae is the plural form of supernova. --Keflavich 15:32, 17 June 2007 (UTC)

All right thank you I was going to change it to supernova hehe

Amoscare 23:29, 17 June 2007 (UTC)Amoscare

Naming convention
I noticed that in the naming convention section it states there are four historical supernovae denoted by the year of discovery alone, but this list doesn't include the earlier mentioned SN 185, which would predate them all. I know precious little on this subject and will leave it to the experts to clarify. —Preceding unsigned comment added by Aax.nox (talk • contribs)


 * I removed the word "four" and inserted SN 185. Thanks. &mdash; RJH (talk) 15:09, 1 August 2007 (UTC)

Clarifying edit summary
Regarding this edit summary, please note that RJHall posted to my talk page at 17:36, July 29, 2007 (UTC), I responded at within minutes, at 17:41, July 29, 2007 (UTC), and I archived my talk page at the end of the month, 18:23, on July 31, 2007. I responded immediately, and he had two days to read my response which is now in my archives. Further, I raised the comma question at WP:MOSNUM and was informed that I was correct. I don't "blank" comments, and I'm surprised to see such aggression over commas because I helped prepare the article for the mainpage. Sandy Georgia (Talk) 00:13, 3 August 2007 (UTC)

Repeated core collapses
This article says "As the star evolves, it undergoes repeated stages where fusion in the core stops, and the core collapses until the pressure and temperature is sufficient to begin the next stage of fusion, reigniting to halt collapse." I assume that the helium flash is the first such stage? Anyway, what I'm wondering is how apparent such "collapses" are to astronomical observers - can you readily see a change in the star on a human time scale and say that it just entered the helium burning stage, etc.?

The other question I have is one of those really stupid ones... I've read the answer but I still don't understand, though. How does it work that a star, by means of burning up all its easy fuel, becomes hotter and larger and with a higher core pressure than a star that still has this fuel available? 204.186.60.84 03:38, 3 August 2007 (UTC)


 * 2nd Q 1st: Generally, when stars become larger, they also becomes cooler (not hotter), if the energy production remains the same. That's logical. But red giants, starting to consume helium, have a higher energy production, in a smaller volume than when consuming hydrogen, so they also becomes red and more luminous. The pressures and temperatures needed for helium to burn are higher, so by some hydrostatic logic that I don't exactly understand, the higher preasures in the core creates lower pressures at the star surface, thus a red giant.


 * 1st Q 2nd: One can't readily see in what stage of evolution a star is, since the burning cores are unavailable for observations, but the astronomers are able to make qualified guesses. Stars at the main sequence (lum class V) are regarded as hydrogen core burners. Subgiants (lum class IV) are regarded as hydrogen shell burners accreting helium at the core. Giants (III) are regarded as helium core burners. AGB stars with increasing heavy metal and carbon atmospheric abundance, are believed to be helium shell burners - so the late helium shell burners are carbon stars, and so very easy to distinguish. But regarding carbon burning and above: a 25 Msun star is expected to spend 600 years of its life burning carbon, while burning hydrogen and helium takes 7500000 years. This means statistically, that among 25 Msun stars (who aren't common), one specimen in 12500 is a carbon burner. Among lower mass stars they're still fewer down to nonexistent. Carbon, neon, oxygen and silicon burners are very hard to find, and then detect, since their mode of burning haven't much time to affect their atmospheric characteristics. Cheap shrinkwrap neutrino detectors would be the sweet dream of any astrophysicist, since then the star cores can be observed directly. (Anyone - correct me if I'm wrong!) Said: Rursus ☺ ★ 07:07, 3 August 2007 (UTC)

Congrats!
Congrats to the featuredness for this article, editors!! Said: Rursus ☺ ★ 07:10, 3 August 2007 (UTC)

is this a bit condensed
"A massive star may cease to generate energy from the nuclear fusion of atoms in its core, and collapse under the force of its own gravity to form a neutron star or black hole." It doesn't quite get across how the supernova happens, is not the small dense object the residue after the bang? I'm not sure I have a good phrase for it, but that might be improved? Coriolise 11:14, 3 August 2007 (UTC)


 * Yes you're right. Is this a better mini-synopsis?
 * "A massive star may cease to generate energy from the nuclear fusion of atoms in its core, and collapse under the force of its own gravity. The result is an explosion of sub-atomic reactions at the core that tears apart the star, leaving behind a neutron star or black hole as a residue."
 * &mdash; RJH (talk) 19:52, 4 August 2007 (UTC)

No remaining core?
I thought I read somewhere (can't find it now) that there was a type of supernova thought to leave no core behind. Was my mind making that up, or did I really read that somewhere? Djfeldman 14:39, 3 August 2007 (UTC)
 * You're probably thinking of a Type Ia supernova, which is the detonation of a white dwarf instead of a star. ~ S0CO ( talk 14:47, 3 August 2007 (UTC)
 * Actually I think you are referring to Pair-instability supernovae. Anynobody 09:34, 4 August 2007 (UTC)

Plasma
removed that the supernova is made of plasma. The remnant neutron star of the type II supernova is not plasma.

Roadrunner 19:19, 3 August 2007 (UTC)

Decay rates
The article contained the text:

These light curves have an average decay rate of 0.008 magnitudes per day; much lower than the decay rate for Type I supernovae. Type II are sub-divided into two classes, depending on whether there is a plateau in their light curve (Type II-P) or a linear decay rate (Type II-L). The net decay rate is lower at 0.012 magnitudes per day for Type II-L compared to 0.0075 magnitudes per day for Type II-P.

Interpreting the graph, and considering the values of the numbers, I believe that the word "lower" should be replaced by "higher", and I have so done. That is, the rate of decay is higher, though, of course, this leads to the brightness of the remnant being lower.

If I have misinterpreted, please feel free to revert, though I would appreciate being told what I have misunderstood. Thanks --King Hildebrand 20:22, 5 August 2007 (UTC)
 * That makes sense to me. Thanks. &mdash; RJH (talk) 15:31, 6 August 2007 (UTC)

Type II timing contradiction?

 * Woolsey and Janka - "the last burning phase — silicon burning — lasts only two weeks."


 * (uni lecture notes) - "Silicon burning duration, 1 day"

Can someone definitively sort the current theoretical timings and durations out for this and related articles? Thanks! FT2 (Talk 11:29, 13 September 2007 (UTC)


 * Woosley and Janka give an 18d period for a 15-solar mass star. The lecture pages give the period for a 25-solar mass star. So they are not inconsistent. For more detail, have a look at page 1020 of: http://www.astrosen.unam.mx/~richer/docencia/astrofisica1/woosleyetal2002.pdf
 * &mdash; RJH (talk) 15:09, 17 September 2007 (UTC)

Unnatural Supernova
Is there any possibility or even a proof of unnatural ways cause supernova happens like caused by bomb or something which suddenly blows up a star? Study on this star killer might be useful if someday in the future we found a star too close to our planetary system that could highly affect our planetary system so we have to kill that star. Ovdl (talk) 20:27, 24 January 2008 (UTC)
 * I imagine it would be much easier (energy-wise) just to push a 100km-diameter asteroid into the path of the Earth than to try to explode a star. That would be enough to finish us off. Otherwise you'd need to cause a collision with a 1.4 solar mass compact object, which would take a lot of energy to move around. But, of course, a super-advanced alien race would have physical knowledge far beyond our own, so how would we even know how to look? Personally I wouldn't worry about it. We're too busy finishing ourselves off to sweat things like that.&mdash;RJH (talk) 18:41, 1 February 2008 (UTC)

yes there is, for example if you could compress an asteroid so that it has the density of a neutron star and toss it into the star, the high gravity will speed of the fusion exponentially and cause a supernova. The time the star would go supernova would depend and the density and mass of the neutron star dense asteroid

Written by phillip alobwede —Preceding unsigned comment added by 68.9.165.23 (talk) 21:15, 8 December 2009 (UTC)

Betelgeuses Supernova
Betelgeuses supernova will form a light that will be about 4 million times the light of the sun. ɰ —Preceding unsigned comment added by 81.156.32.168 (talk) 09:24, 23 February 2008 (UTC)

Supernovae in fiction
Possible merge into this article, as it stands, Supernovae in fiction is unlikely to survive on its own in its current state SGGH speak! 16:24, 3 March 2008 (UTC)
 * (1) Precedent is for "X in fiction" pages, where X is a scientific article, to be placed in separate articles. (2) This material is not properly cited, whereas supernova is an FA rated article. The addition of this material would subject the supernova page to an FAR and possibly demotion. So it would need to be stripped out. (3) Strictly speaking, yours does not seem to be a good reason for a merge. If the material is properly cited then the fiction article should stand by itself. If it is not, then it doesn't belong here. (4) The article is longer than the suggested length already. Significant amounts of material have been spun off into separate articles in order to shrink it down. (C.f. Type Ia supernova, Type Ib and Ic supernovae andType II supernova.) I don't think a merge would be beneficial in this respect. &mdash;RJH (talk) 16:30, 3 March 2008 (UTC)

Wording
The following statement seems to undergo a lot of re-wording:
 * They are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy before fading from view over several weeks or months.

It is flawed because galaxies come in many dimensions, so it could just as easily say "always", rather than "often" or "may". The original wording was as follows:
 * A supernova usually causes a brief burst of radiation which may briefly outshine its entire host galaxy before fading from view over several weeks or months.

Is there a better wording that would serve this purpose and say something more useful? Perhaps "outshine the largest known galaxies" or some such.&mdash;RJH (talk) 15:19, 7 May 2008 (UTC)

Supernova imposter
As this phrase is starting to become commonplace in scientific circles, it is about time someone started a page about them ! There's also a few examples floating a round the net. A mention could also be made in this page. The Yeti (talk) 22:08, 22 September 2008 (UTC) (trying to create work for someone :)
 * Yes I agree that topic should have its own article. Once such a page is set up and cited, a mention here wouldn't hurt; at the very least it could be added to the "See also" section. Have you tried discussing this on Wikipedia_talk:WikiProject_Astronomical_objects or Talk:Variable_star? Thanks for the suggestion.&mdash;RJH (talk) 18:47, 23 September 2008 (UTC)
 * I've started a very small wikipedia page on Supernova imposter Mollwollfumble (talk) 03:43, 24 February 2009 (UTC)

Supernova progenitor addition
I am a little confused on the format. Could someone add U Scorpii to the list of supernova progenitors? see url http://www.aspbooks.org/a/volumes/article_details/?paper_id=24473 —Preceding unsigned comment added by 75.33.59.12 (talk) 18:15, 26 January 2009 (UTC)
 * Okay it's added. Thank you for bringing that up. The list of progenitors is getting long enough that it might make sense to create a separate List of supernova candidates (or progenitors?) article.&mdash;RJH (talk) 20:56, 26 January 2009 (UTC)

What's a Ia-p?
Harvard http://www.cfa.harvard.edu/iau/lists/RecentSupernovae.html uses the supernova type Ia-p, which isn't mentioned on this page. What is it? In addition, I note that types IIn and IIb are described outside the supernova taxonomy table when they should be in it. There should also be a mention of type Ib/c &/or Ibc. Mollwollfumble (talk) 02:07, 24 February 2009 (UTC)
 * I think the 'p' is short for peculiar. I agree that those types should be covered, but I also like the clean form of the current taxonomy table.&mdash;RJH (talk) 18:48, 24 February 2009 (UTC)
 * Type Ibc just appears to be a shorthand notation for category of "Type Ib and Type Ic" supernovae. .&mdash;RJH (talk) 21:01, 4 March 2009 (UTC)

Section: "Discovery"
The section: Discovery seems to treat how to discover new supernovae. Now regarding the other interpretation: "when were the supernovae discovered?", when was the distinction between novae and supernovae discovered? We must remember that Tychos Nova and Keplers Nova, were initially regarded just novae. I'm not sure, but I think that SN 1885 And was kind of a starting point for distinguishing between novae and supernovae. In the 1920:s it would be clear by the extragalactic nature of the Andromeda "Nebula", that SN 1885 And belonged to a different class than the ordinary novae. ... said: Rursus (bork²) 17:59, 28 February 2009 (UTC)
 * Good points. Perhaps the Discovery section should be renamed to something like Identification? I think the first half of the History_of_supernova_observation section at least partly addresses your second concern.&mdash;RJH (talk) 20:09, 28 February 2009 (UTC)

Impact on Earth
This section had grown sufficiently that I think it can now stand alone as its own article, to undergo further expansion. I replaced the section with a summary style copy and put the full contents out to Near-Earth Supernova. Note that the topic of near-Earth supernova was originally created in a separate article and merged in here, but this article has since grown significantly.&mdash;RJH (talk) 20:32, 9 March 2009 (UTC)


 * Am I the only reader who sees the word "impact" and thinks we're talking about physical collision? I mean, I know that a supernova near earth would in fact eject matter toward earth at a very high velocity, but that ejected matter would be so rarefied that it wouldn't be what we normally think of as an impact, right? Maybe "effect" would be a better word. Contributions/65.213.77.129 (talk) 19:20, 15 June 2009 (UTC)


 * One of the meanings of impact is synonymous with "effect".&mdash;RJH (talk) 22:50, 15 June 2009 (UTC)


 * Yes, I know that. I'm just suggesting that since "effect" is less ambiguous and is synonymous with the sense of "impact" in question, it would be preferable in order to avoid the possibility of confusion. Do you disagree? 65.213.77.129 (talk) 12:54, 16 June 2009 (UTC)


 * Sure, no problem here. Thanks.&mdash;RJH (talk) 16:24, 16 June 2009 (UTC)

Core collapse
I guess it was already discussed in the past, but I have to ask. There is a heavy weight for observational classification (as should be), but the search for "core collapse supernova" leads nowhere. It is a matter of almost a consensus that type Ia are not and the rest are, and it is not very clear from first reading. Maybe there should be a short comment about it in the beginning, or even a page "core collapse supernova" stating some basic physical classification? —Preceding unsigned comment added by Ranny1 (talk • contribs) 14:56, 7 May 2009 (UTC)
 * I'm not quite clear why there is a concern about this. The "Energy output" section explains the term.&mdash;RJH (talk) 16:47, 7 May 2009 (UTC)

Type IIn Supernovae?
In a recent news by Sky & Telescope there are Supernovae of type "IIn" mentioned ("...designated Type IIn supernovae, which result from very massive stars."). Anybody knowledgeable of these? ––ECeDee (talk) 08:06, 15 July 2009 (UTC)
 * These are mentioned in the classification section and discussed somewhat in Type II supernova.&mdash;RJH (talk) 23:51, 18 July 2009 (UTC)

Type Ia Variability
An article that may be of interest for this and/or related pages, concerning variablity in luminosity of Ia explosions:

http://www.astronomynow.com/news/n0908/13sn/

The Yeti (talk) 11:30, 17 August 2009 (UTC)


 * Yes, it is an interesting development with regard to the use of Type 1a's for standard candles. I think the information is based on computer models, so I don't know if it has been confirmed in the field yet.&mdash;RJH (talk) 19:24, 18 August 2009 (UTC)

Fusion of elements heavier than iron?
Okay, so the "normal" stellar nucleosynthesis fusion processes starting from hydrogen run out as the star produces iron. This then apparently causes the star to begin to collapse as the internal thermal energy from fusion decreases and is unable to support the upper layers of accreted material around the core.


 * What is the specific trigger that causes fusion of the heavier elements? Does the inward collapse reach a point where the inward pressure is enough to trigger the heavier fusion event, and is that what explodes of the star? DMahalko (talk) 22:37, 20 August 2009 (UTC)
 * Is the heavier fusion a sustainable process, or does it only occur as a scattered unsustainable explosive event, occurring only along the compressed leading edge of high-intensity shock waves spreading outward through the overall exploding star? DMahalko (talk) 22:37, 20 August 2009 (UTC)


 * As far as I can tell from related articles, fusion of elements heavier than iron mostly happens via the s-process, the r-process, and the p-process. These involve adding individual neutrons (first two) or protons (last process) to atoms, rather than having atoms merging. The s-process slowly adds neutrons during the normal life of the star, as neutrons are plentiful with all of the fusion going on. This is similar to the type of transmutation that happens in breeder reactors on Earth. The r-process happens during the supernova explosion, when huge amounts of fusion happen and huge numbers of neutrons are produced. This can produce isotopes that slow transmutation can't (multiple neutrons can be absorbed before the daughter isotope decays). The p-process is like the r-process, but with free protons rather than neutrons being absorbed.


 * With regards to fusion of iron within the star's core, fusion reactions of many types will happen, backwards and forwards (much as with chemical equilibrium for chemistry). Iron is one of the most stable products of the reaction, so it accumulates. As there's no more net transmutation happening or production of energy, the core stops helping to support the star and sits there as a lump of degenerate matter until degeneracy pressure can no longer support it. So, production of elements heavier than iron could be considered an unsustainable process per your question above (it costs energy rather than producing it, and a system in equilibrium will probably fission these back to iron). --Christopher Thomas (talk) 23:32, 20 August 2009 (UTC)

Where is the evidence of the supernova?
Question?

I believe it was the science channel that said our solar system was created from the material left over from a supernova in the outer part of the Milky Way galaxy. If this is true and the Wikipedia article is correct on the two ways supernovae happen, then where is the neutron star, black hole or companion star? I am not an educated in a science discipline, only very interested. —Preceding unsigned comment added by 99.194.112.57 (talk) 12:58, 12 September 2009 (UTC)


 * It's been long enough since the solar system formed that the black hole or neutron star could be anywhere in the galaxy by now (they're often moving pretty quickly relative to the nebula left behind). The evidence for our solar system having been formed from a supernova remnant is the presence of elements heavier than lithium. The primordial cloud the galaxy formed from only had hydrogen, helium, and lithium in it (per big bang nucleosynthesis). Population III stars produced some of the heavier elements, and Population II stars produced the rest, so our own sun (and solar system) formed from the remains of one of these stars. --Christopher Thomas (talk) 16:13, 12 September 2009 (UTC)


 * Although it likely won't be the stellar remnant of the supernova you mention, the Gaia mission may be capable of finding one of the Sun's long-lost siblings. There's an article about it on the SciAm site. That will make for an interesting comparison.&mdash;RJH (talk) 17:31, 4 November 2009 (UTC)

we have already been thru a supernova our sun is at the stage of the cooling period we did live further out likes of mars some how we jumped to earth our next jump aint far off  eddie tate eddsatwats@live.co.uk —Preceding unsigned comment added by 82.22.136.190 (talk) 23:09, 3 November 2009 (UTC)

Triggers for a type 1a supernova
Paragraph 2 of this article states "Alternatively, a white dwarf star may accumulate sufficient material from a stellar companion (usually through accretion, rarely via a merger)...". This seems to be contrary to a recent news release from the Max Planck Institute for Astrophysics: http://www.mpg.de/english/illustrationsDocumentation/documentation/pressReleases/2010/pressRelease20100105/index.html

I am not sufficiently knowledgeable about this subject to change this myself, but others with more knowledge might consider a change based on this new information. —Preceding unsigned comment added by AllanJohnstone (talk • contribs) 19:56, 7 January 2010 (UTC)


 * This is worth watching, but the press release's claim about mergers representing the majority of Type Ia supernovae cites a single, not-yet-published paper. So, I'd wait a little longer before altering the text to reflect this statement (though it may well be correct). --Christopher Thomas (talk) 22:36, 7 January 2010 (UTC)


 * Actually the statement using the terms "usually" and "rarely" is unsourced, so I don't think it would hurt to modify that slightly and remove the vague wording. Thanks.&mdash;RJH (talk) 15:42, 8 January 2010 (UTC)

second paragraph
The second paragraph in the lead section begins with a sentence introducing "Several types of supernovae", and then jumps awkwardly to a discussion of only two types. Instead, I suggest one of these approaches: "Several types of supernovae exist. The primary Types I and II can be triggered in one of two ways..." or "Supernovae are classified according to their spectral characteristics into two primary types and several sub-types. Types I and II can be triggered ...". Having said that, however, the whole paragraph seems a bit much for the lead section, and its lack of citations leaves the inquisitive reader with a huge amount of reading just to figure out where to flesh-out the details.--Rich Janis (talk) 02:00, 30 April 2010 (UTC)
 * Yes, the original paragraph from when the article was promoted to featured status was shorter and (in my opinion) somewhat cleaner (although the current version is more concise). It has undergone multiple revisions since that time.
 * Old: There are several types of supernovae and at least two possible routes to their formation. A massive star may cease to generate energy from the nuclear fusion of atoms in its core, and collapse under the force of its own gravity to form a neutron star or black hole. Alternatively, a white dwarf star may accumulate material from a companion star (either through accretion or a collision) until it nears the Chandrasekhar limit of roughly 1.4 times the mass of the Sun, then undergoes runaway nuclear fusion in its interior, completely disrupting it. This second type of supernova is distinct from a surface thermonuclear explosion on a white dwarf, which is called a nova. Solitary stars with a mass below approximately 8 solar masses, such as the Sun itself, will evolve into white dwarfs without ever becoming supernovae.
 * Current: Several types of supernovae exist. Types I and II can be triggered in one of two ways, either turning off or suddenly turning on the production of energy through nuclear fusion. After the core of an aging massive star ceases generating energy from nuclear fusion, it may undergo sudden gravitational collapse into a neutron star or black hole, releasing gravitational potential energy that heats and expels the star's outer layers. Alternatively a white dwarf star may accumulate sufficient material from a stellar companion (either through accretion or via a merger) to raise its core temperature enough to ignite carbon fusion, at which point it undergoes runaway nuclear fusion, completely disrupting it. Stellar cores whose furnaces have permanently gone out collapse when their masses exceed the Chandrasekhar limit, while accreting white dwarfs ignite as they approach this limit (roughly 1.38 times the mass of the sun). White dwarfs are also subject to a different, much smaller type of thermonuclear explosion fueled by hydrogen on their surfaces called a nova. Solitary stars with a mass below approximately nine solar masses, such as the Sun, evolve into white dwarfs without ever becoming supernovae.
 * I'm sure we can re-use cites from throughout the article, but I'm not sure they would make the information clearer&mdash;RJH (talk) 14:50, 30 April 2010 (UTC)

Here's an even more basic version:


 * Several types of supernovae exist. A type Ia supernova occurs when a white dwarf star gains enough material to raise its core temperature enough to ignite carbon fusion, at which point it undergoes runaway nuclear fusion, completely disrupting it. This increase in mass may be caused by accreting matter from a stellar companion or via a merger. Another type of supernova occurs when the core of an aging massive star is no longer able to support itself and undergoes a sudden collapse into a neutron star or black hole. This causes a release of gravitational potential energy that heats and expels the star's outer layers. Solitary stars with a mass below approximately nine times the mass of the Sun evolve into white dwarfs without ever becoming supernovae.


 * White dwarfs are also subject to a different, much smaller type of thermonuclear explosion fueled by hydrogen on their surfaces called a nova.

Not leaving or does not leave
Regarding this correction, my revert and Gomphothere's uncommented undo of my revert. It looks like Gomphothere misunderstands the sentence and thinks that the pair-instability does not leave the black hole, whereas it is the large quantity of elements which don't leave the hole. In the latter case the grammar was correct as I explained in my edit summary. Any comments? DVdm (talk) 16:16, 19 May 2010 (UTC)


 * Pasted in from User talk:DVdm:


 * Parsing out the elision and rendering the sentence as:
 * "This pair-instability supernova creates a larger quantity of elements which are heavier than helium ('metals') than in other types of supernova and which are not leaving a black hole remnant."
 * does not rescue it. The most natural interpretation of the second "which" clause now has it referring to "elements," but it is not "elements" which are "not leaving a black hole remnant."
 * Gomphothere 16:28, 19 May 2010 (UTC)


 * The sentence is referring to the fact that pair-instability supernovae do not leave behind black holes (unlike other types of supernovae involving very massive stars). The grammar of the sentence above would suggest that they do leave a black hole as a remnant, and that the heavy elements synthesized cannot escape the black hole. Not only is the grammar bad, but it is factually inaccurate. Any misunderstanding is on the part of either you or the original writer. Gomphothere 16:37, 19 May 2010 (UTC)


 * So, indeed we now have the sentence: "This pair-instability supernova creates a larger quantity of elements heavier than helium ("metals") than in other types of supernova and does not leave a black hole remnant." The only way that I can interpret this is that it says that "this pair-instability supernova does not leave a black hole remnant." If that is the meaning, then I agree with your correction. Do we have a citation for this? DVdm (talk) 16:44, 19 May 2010 (UTC)


 * src "The resulting thermal energy is so huge that it blows the star completely apart, leaving behind nothing behind. All other supernovae leave behind black hole or neutron star remnants." Gomphothere 16:56, 19 May 2010 (UTC)


 * Excellent, thanks. The problem was with the fact that "to leave behind" was shortened to "to leave" and I had interpreted the verb "to leave" as meaning "to move away and escape from". I have added the word "behind" at the end of the sentence. Hopefully this will make future confusion less likely. Cheers. DVdm (talk) 17:10, 19 May 2010 (UTC)
 * The updated version is clearer; thank you for catching the ambiguity.&mdash;RJH (talk) 17:49, 19 May 2010 (UTC)


 * I'm going to remove that word because it doesn't disambiguate anything. In fact, it suggests the unintended meaning of "leave" you just quoted by implying the relationship between the supernova and the remnant is spacial rather than temporal. How about this?
 * "This pair-instability supernova creates a larger quantity of elements heavier than helium ('metals') than other types of supernova and leaves no black hole in its wake."
 * Gomphothere 17:55, 19 May 2010 (UTC)


 * Even better. Good one. DVdm (talk) 18:00, 19 May 2010 (UTC)
 * Sorry but I have to disagree. "in its wake" is unclear language with two possible interpretations.&mdash;RJH (talk) 21:21, 19 May 2010 (UTC)
 * Erm... perhaps "... leaves no black hole as a remnant" then. I have made the change. Feel free to amend further. Trickky :-) DVdm (talk) 21:55, 19 May 2010 (UTC)
 * I was avoiding "remnant" because it seems to be a term of art with the wrong connotation. By the dictionary definition it fits, but this usage is at odds with the definition in Supernova remnant which actually describes something that would in fact be produced. There are always alternative interpretations, but I don't see any for my wording that aren't absurd. Clearly we're not talking about boats. Since RJH's concern could be applied verbatim to most any English statement I'm unsure how to weigh it in determining which wording would be clearer. Gomphothere 22:33, 19 May 2010 (UTC)
 * To clarify: one interpretation of "in its wake" was that something was moving away and leaving a wake behind. As it is not uncommon for core collapse supernovae to give a remnant a momentum kick, that clearly that could cause all sorts of confusion. Hence I think it should be changed to use clearer language.&mdash;RJH (talk) 22:49, 19 May 2010 (UTC)

Supernovae as plural
I have to say that I am very impressed with this article and with the dedication to stringent accuracy that the editors on this article exhibit. That said, why is the plural specified for this word Latin instead of English?--Jarhed (talk) 08:00, 28 July 2010 (UTC)


 * The Latin form seems to be more common. Compare Google Scholar supernovae with supernovas. On the popular side, see Google fight. DVdm (talk) 10:11, 28 July 2010 (UTC)


 * English, being the melting-pot that it is, will sometimes use the Latin plural form for words. Usually this happens for words used by scientists, as scientific naming conventions tend to use a mixture of latin and greek (ditto words used in medicine). --Christopher Thomas (talk) 16:34, 28 July 2010 (UTC)
 * Yes it probably has a lot to do with the greco-latin scholarly tradition. But I wouldn't be surprised to see supernovae follow the path of words like antennae, aurorae, formulae and nebulae; slowly phasing out the -ae in favor of an -s.&mdash;RJH (talk) 21:00, 29 July 2010 (UTC)


 * In the future? Perhaps. But language reform hasn't worked very well the last few times it was tried (it mostly made British, Canadian, and American English farther out of synch with each other). --Christopher Thomas (talk) 21:31, 29 July 2010 (UTC)


 * I am delighted by the collegiality exhibited here. Last thing: I note that Mirriam-Webster lists both plurals for this word, the Latin and the English.Jarhed (talk) 20:21, 1 August 2010 (UTC)

NASA'S Chandra Finds Youngest Nearby Black Hole
An object which is believed to be a remnant of supernova SN 1979C has been found 50 million light years away. Perhaps this will be a good fit for this article? http://www.nasa.gov/home/hqnews/2010/nov/HQ_10-299_CHANDRA.html DavidR2010 (talk) 14:45, 16 November 2010 (UTC)DavidR2010
 * It might be a little too much of a low-level detail for this article, which is intended as a high level summary of all supernovae. Possibly it could be added to History of supernova observation?&mdash;RJH (talk) 18:01, 16 November 2010 (UTC)


 * Thanks lets put it up there I will add this to the discussion over there DavidR2010 (talk) 18:26, 16 November 2010 (UTC)DavidR2010

Disbelief: Cf
Disbelief that Cf have ever been detected in supernovae, see Talk:Californium. Rursus dixit. ( m bork3 !) 12:59, 30 November 2010 (UTC)

Wiki Education Foundation-supported course assignment
This article is or was the subject of a Wiki Education Foundation-supported course assignment. Further details are available on the course page. Student editor(s): Gmusto11, DanielleHall07.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 10:28, 17 January 2022 (UTC)

Pronunciation
As far as I've seen, there is no WP standard that says an article must insert a flow-disrupting pronunciation guide in the first sentence of an article. Hence I moved it down following the definition and turned it into a more complete sentence. If there is a concern with this change, please clarify. Thank you.&mdash;RJH (talk) 19:22, 2 May 2011 (UTC)


 * I've erased "pron" from the first formula so that it'd look more text-like. All the options preserved. Josh, linguist (talk) 11:39, 19 March 2013 (UTC)

Furthermore I doubt that two native German-speaking scientists who coin a Latin neologism would at the same time not hesitate to introduce a new official Latin pronunciation which, I have to state it, sounds pretty English. — Preceding unsigned comment added by 217.6.16.93 (talk) 08:53, 9 January 2015 (UTC)

New candidate supernova class
See: Regards, RJH (talk) 17:24, 8 June 2011 (UTC)

Close supernova
I just read about a supernova that is supposed to happen very soon, that is extremely close to earth. A more proficient editor than me should add it. Here's the article. http://science.cabot.ac.uk/index.php/2011/10/a-star-set-to-blow/

75.92.160.60 (talk) 21:27, 2 October 2011 (UTC)
 * It would be more appropriate for History of supernova observation. This is an article about supernovae in general. Regards, RJH (talk) 19:20, 4 October 2011 (UTC)

Newer Supernova Than stated in this article has now been confirmed.
G1.9+0.3 Has been confirmed as the youngest supernova within the Milky Way galaxy. ref. http://news.nationalgeographic.com/news/2008/05/080514-supernova_2.html

To summarize:

Supernova G1.9+0.3 discovered by Stephen Reynolds and his team at North Carolina State University has been confirmed as the youngest supernova discovered to date, it is estimated at only 140 years old and located within the constellation of Sagittarius. Although obscured by interstellar mass at the time of it's explosion recent studies of it have shown it to be a rapidly expanding and very young supernova, currently the youngest confirmed by astronomers. — Preceding unsigned comment added by 184.59.144.219 (talk) 04:09, 11 February 2012 (UTC)

Is it true? Drajaytripathi (talk) 04:58, 13 June 2015 (UTC)

Yes this is true PugLover.2016 (talk) 07:01, 10 July 2016 (UTC)

Date of the word supernova
The introduction says that "supernova" was first used in print in 1926 (according to Merriam-Webster). Under "Discovery" it says that it was first used in a lecture in 1931 and at a meeting of the APS in 1933. In the article about Fritz Zwicky it says that the word was coined by him and Walter Baade in 1934.

In Fritz Zwicky: Novae Become Supernovae by T Koenig (http://articles.adsabs.harvard.edu//full/2005ASPC..342...53K/0000058.000.html) it says that Zwicky and Baade had been using the term since 1931 and that the first publication in print was by Knut Lundmark in 1933 (article dated Dec 31 1932).

Zwicky writes himself in Types of novae (http://authors.library.caltech.edu/4785/1/ZWIrmp40.pdf footnote on page 85): Baade and I first introduced the term "supernovae" in seminars and in a lecture course on astrophysics at the California Institute of Technology in 1931.


 * This source seems to sum it up pretty well:
 * Regards, RJH (talk) 22:51, 25 February 2012 (UTC)
 * Regards, RJH (talk) 22:51, 25 February 2012 (UTC)


 * But "The word supernova was coined by Swiss astrophysicist and astronomer Fritz Zwicky, and was first used in print in 1926", as it says in the introduction, is contradictory to that it was first used by Zwicky in 1931 and also to that it was first used in print in 1933. And 1934 as given in in the article on Fritz Zwicky is also contradictory. — Preceding unsigned comment added by 83.254.200.12 (talk) 09:01, 26 February 2012 (UTC)
 * Yes, I agree. The introduction, and its corresponding source, would appear to be in error. We should use the Osterbrock (2001) source for consistency. Regards, RJH (talk) 20:19, 28 February 2012 (UTC)

like to raise two points which I think should be corrected within the article.

First, the introductory chapter contains lots of stuff that simply isn't relevant to someone trying to find out what a supernova is, at the surface level. True, what I tried to do with my edits was to shorten it, because I have a problem with overly long intros. And I know that brevity is formally very much not a criterion for the intro, as a matter of written policy.

But still, relevance to a first time learner I believe is. From that viewpoint I would think what has to be told is a) it's an unusually and suddenly luminous star, b) long after we saw them the first time, we learned that there are many different kinds of them, c) one or two representative examples of the thing, and d) the fact that they are believed to be caused by different modes of runaway fusion. That's it; I believe the rest of the details should be pushed down into the body of the article, because before you can understand the differences, you need a huge lot of preliminary text to understand it, which can only fit the body format.
 * The lead is written according to the guidelines in WP:LEAD in that it is intended as a summary of the primary points of the article. It is three paragraphs long, which is less than the maximum for a long article like this. I found your edits to the lead to be heavy handed and overly extensive. It has been thoroughly reviewed by many editors (hence the FA rating), and thus I believe it is just fine for the purposes of this encyclopedia. Please keep in mind that your concern about the supposed excess length is one opinion among many; other reviewers find brief leads to be equally objectionable. I'd like to keep it in balance with the prevailing standards and past consensus. Regards, RJH (talk) 18:25, 20 June 2012 (UTC)
 * That is then why I brought my concerns onto the talk page. I'm arguing for a particular stylistic choice, which we evidently do not agree about. Both those choices fall within the guidelines and you've already reverted my idea. Thus, I'm seeking further output and consensus before touching the article further. Decoy (talk) 22:59, 20 June 2012 (UTC)

The second part is that, right now, the physical theory concerning supernovas is interspersed widely within the article, as is the astronomical data we have of them. Your mileage may vary, but I think those aspects should be separated and concentrated into their own sections, so as to make for tighter presentation, which can then also be more easily found from the topmost content listing. Especially since I think people simply interested in the night sky and the ones interested in stellar dynamics are two different crowds, with two different needs. As such, I'd advocate a wholesale content-retaining reorganization at the level of single claims. That is not as big or difficult as it sounds, but it might seriously help a total newcomer internalize the contents better, while not taking away anything from the expert.
 * The physical models for supernova are contained in the "Current models" section, so I find your statement puzzling. Note that the lead should be redundant with elements of the article body, which is why we don't need to relocate content from the lead into the article. To me the article flow is logical and I'll object to a wholesale rewrite without a solid plan and a wider consensus. Perhaps you could clarify your perspective with some specific examples? Regards, RJH (talk) 18:30, 20 June 2012 (UTC)
 * I mostly agree. But I think the redundancy in the introductory section should be minimal, and that it should only mention, not explain or reason with, what is contained in the body. I agree that my edit was heavy handed, and I'm happy that you reverted it. But I also believe something even better could be found between the basic idea of what is now in there and what I tried to put there.


 * Two particular examples wrt the intro chapter would be the precise velocity estimate of what supernovas put out, and the mention of shockwaves in the interstellar medium. They are sequelae of the process, not defining factors of what a supernova really is. In fact, they vary widely depending on what the local matter density actually is and how the supernova happens to come into being. What is left of it as well; all of that is, I think, better handled in the body of the article, by moving the relevant content there. Decoy (talk) 22:59, 20 June 2012 (UTC)

Finally, don't get me wrong. The article is exceptionally good as it stands, as evidenced by its featured status. It's just that I think it could be even better. Right now I'd say its structure is at the level of a rather good encyclopedia article. But it ain't yet a Feynmann lecture, where every question is answered precisely when you were about to ask it in the logical procession of things, if you know what I mean. Decoy (talk) 18:06, 20 June 2012 (UTC)
 * This is an encyclopedic article, so it should most definitely not be turned into a Feynmann lecture. (Yes I have read Feynmann.) If you want to build an in depth presentation, I strongly urge you to try the Wikiversity or Wikibooks projects; those have very different goals than a straight-forward encyclopedic presentation of the facts. Regards, RJH (talk) 18:30, 20 June 2012 (UTC)
 * I agree that the summary paragraph needs work. It can't be a coincidence that this reverted edit was almost identical to one I tried to make a few weeks back.  The summary may only be three paragraphs, but one of those paragraphs (the only one that really has a problem) is overly long and not at all a concise summary of any portion of the rest of the article.  Some of it is simply incorrect.  My response to these problems was just to remove three quarters of that paragraph, but perhaps it could be written in a better way. Lithopsian (talk) 20:10, 20 June 2012 (UTC)
 * The concern I had with Lithopsian's modification to the lead is that it just moved a chunk of text down into the article; that should not be happening because the lead should be a summary of the article. It sounds like we need to start by reaching a consensus on how to write the lead. The consensus rule of thumb on the lead is to have at least one sentence per article section, and to mention the major points in the presentation.


 * As it happens, the large paragraph in question was previously two separate paragraphs; somebody came along and combined them. (Compare, for example, to the version at the FA promotion.) This sort of trivial modification happens frequently on Wikipedia and it isn't always beneficial. It should be easy enough to split it again. However, I can guarantee you that whatever we come up with will not remain intact over time. All we can do is try to maintain it in a somewhat recognizable form. Regards, RJH (talk) 21:16, 20 June 2012 (UTC)
 * What I mean by my reference to the Feynman Lectures is not about their content, but their explanatory style and well-structured flow of thought. They go to extraordinary lengths in teaching stuff in an order that is understandable, easily memorable, and logic-wise coherent. I believe such a style of presentation is a merit to an encyclopedia article as well, even if it's patently clear that these two genres are very separate an sich.


 * So, I mostly agree. But I wouldn't call reorganization which leaves the content intact, while aiming to improve its flow at the same time, trivial. Nor would I stop text movement which aims to achieve those goals. I did my changes precisely because I care about that sort of stuff quite a lot. I don't dispute your viewpoint about my heavy-handedness or the one about my lack of proper grammar, since I'm not a native speaker of English myself. But at the same time, I do think I have a point to make about the flow of thought. Perhaps *especially* because I'm what they call an "avid amateur", so that I can look at the article from a learner's point of view. Decoy (talk) 22:59, 20 June 2012 (UTC)


 * I've edited that second paragraph in the summary. I've removed or reword things that are inaccurate.  It is considerably shorter but at least not misleading now.  I think it is a good length and says what needs to be said? Lithopsian (talk) 22:47, 21 June 2012 (UTC)


 * I'm basically done with the structural changes and edits, mostly to the sections on classification and models. These should now be consistent with current research.  I'm still waiting on feedback about merging the type II and type Ib/c articles into a single core collapse article, and possibly much of the core collapse section could then go there, leaving just a summary in this article because it is quite long right now with a lot of detail. Lithopsian (talk) 17:58, 24 June 2012 (UTC)

Neon over oxygen?
In the diagram http://en.wikipedia.org/wiki/File:Evolved_star_fusion_shells.svg, it shows the shell of neon (atomic number 10) above oxygen (atomic number 8). It this correct? http://en.wikipedia.org/wiki/White_dwarf#Stars_with_low_to_medium_mass states that "If the mass of a main-sequence star is between approximately 0.5 and 8 solar masses, its core will become sufficiently hot to fuse helium into carbon and oxygen via the triple-alpha process, but it will never become sufficiently hot to fuse carbon into neon." So in this star, why would Neon-20 float above Oxygen-16?

As I am not an astrophysicist and lack the skills to modify that diagram anyway, I thought I would start this discussion. If I am wrong, it would be nice if this good article explained why the neon shell would be above the oxygen. 71.22.115.39 (talk) 16:15, 25 November 2012 (UTC)OxyB4Neon


 * The image is hopelessly naive and over-simplified. Still, for what its worth, Neon starts burning at a lower temperature, and therefore before, Oxygen, and any Neon shell will be found below the Carbon shell and above the Oxygen shells.  So the image should be considered correct. Lithopsian (talk) 18:13, 25 November 2012 (UTC)

So, I guess the triple-alpha process only produces some oxygen and is overshadowed by a later process after neon burning. Okay, then why would the oxygen not bubble above the neon, given it's lighter atomic weight?

Also, looking at http://en.wikipedia.org/wiki/Alpha_process, it shows that you cannot get neon with oxygen as a precursor. What am I missing? oh. I found it, at http://en.wikipedia.org/wiki/Carbon-burning_process. It seems that carbon-burning results in sodium, magnesium, oxygen as well as neon. Still, this only occurs in stars great then 8 solar mass so I am at a loss as to why the oxygen does not float above the neon.71.22.115.39 (talk) 20:37, 2 December 2012 (UTC) OxyB4Neon


 * Nothing to do with "floating". This is burning.  Neon burns first.  The diagram indicates the location of shell burning, not the location of actual elements.  Various elements occur mixed all over the place, especially Magnesium, Oxygen, and Neon which are all produced together from Carbon. Lithopsian (talk) 20:43, 2 December 2012 (UTC)

Classification
Should this be mentioned? "Types of Supernovae Type Ia.	 These result from some binary star systems... Type II.	 These supernovae occur at the end of a massive star's lifetime..." "However, these types of supernovae were originally classified based on the existence of hydrogen spectral lines: Type Ia spectra do not show hydrogen lines, while Type II spectra do. ... However, if the original star was so massive that its strong stellar wind had already blown off the hydrogen from its atmosphere by the time of the explosion, then it too will not show hydrogen spectral lines. These supernovae are often called Type Ib supernovae, despite really being part of the Type II class of supernovae. Looking at this discrepancy between our modern classification, which is based on a true difference in how supernovae explode, and the historical classification, which is based on early observations, one can see how classifications in science can change over time as we better understand the natural world." (Those were quotations.) Josh, linguist (talk) 12:01, 19 March 2013 (UTC)


 * It is mentioned, in great detail. Possibly too much detail.  Read the sections on supernova models.  It could be more succinct in this top level article, which might be easier to follow, but until the detail articles are rationalised I don't want to delegate all the detail. Lithopsian (talk) 12:39, 19 March 2013 (UTC)


 * First, I think it still should be mentioned somehow in the "lede" of the pertaining section. That the "taxonomy" doesn't represent primary differences in general. Second. You say the article should be liter or what? Then I suggest if we draw not that (or another) formal classification first, but give a trivial "taxonomy" on the matter — types (or 'kinds') of supernovae - depending on the processes involved. THEN it's followed by the table with that formal classification. What do you think? AN IDEA! What about preceding the "Classification" section by that new one to depict those major types of blow-ups I meant? For example, we could depict the few different known types of environment producing SNe. If that is described in the following "Current models" section, I mean, for an amateur reader (especially when s/he goes into this for the first time or so), some rough phenomenon adumbration may come first. You may say the overall idea might already be gained in the article's lede, but I think, if the lede is delivering the "main overall" — i.e. what t.f. it is (the matter leaps out due to the pressure of either sort), the suggested "distinguishing" section could roughly describe the needed circumstances in the least formal way. Or, either way, we could shift the existent sections — with making some ordering corrections. PS. As for that "detailedness" of this article you mentioned above, I saw some score of rather much more "abundant-in" ones, now in comparison, this one looks not at all very monstrous for me:) Josh, linguist (talk) 15:04, 21 March 2013 (UTC)


 * The lead does mention the two types, but I feel it is rather lost in the second paragraph. Have to be careful messing with the lead on a featured article but it could probably be improved. Lithopsian (talk) 22:26, 21 March 2013 (UTC)

New Type of Supernova
I think this should be also mentiond: Harvard press release: new kind of supernova. But my english is not so good. Can someone ad this? Catadupa (talk) 09:24, 27 March 2013 (UTC)
 * It doesn't seem major. ? Josh, linguist (talk) 13:09, 27 March 2013 (UTC)
 * It isn't major, but it still deserves a mention. Probably in the type Ia detail article. I thought it might already be there, but a quick look doesn't show anything.  If nothing else, it is interesting because it blurs the line between the non-destructive novae and supernovae which completely destroy the star.  Lithopsian (talk) 13:51, 27 March 2013 (UTC)

Here are articles I found about it: I hope they help. --Richard-of-Earth (talk) 19:14, 28 March 2013 (UTC)
 * They look same... To pile it out, Astronomers have discovered a new miniature version of a supernova. Josh, linguist (talk) 12:41, 2 April 2013 (UTC)
 * The links above are wrong, but there really are two papers. They are both referenced in the article already.  We should avoid using press releases and other web pages as references when the real deal is available. Lithopsian (talk) 14:57, 2 April 2013 (UTC)
 * Fixed the link of Double-detonation explosions as progenitors of type Iax supernovae. As for the abstract summary, it says suggested class name of "type Iax supernovae" (SNe Iax).  But the paper is 2013.  Not sure it the name is accepted in 2014.  Thanks, Marasama (talk) 09:50, 10 August 2014 (UTC)

Nomenclature
Article should clarify whether the "SN[YEAR] XX" naming system would apply to Milky Way objects - I don't think that it does. Presumably we would have (for example) "Supernova Sagittarii 2013", with GCVS name assigned shortly thereafter (e.g. "V5991 Sagittarii"), as opposed to (e.g.) "SN 2013mb", if a Milky Way supernova were discovered in modern times. — Preceding unsigned comment added by 184.47.125.210 (talk) 19:00, 22 August 2013 (UTC)

Asymmetry section
I do not understand the first sentence in that section and I think that probably a word is missing.--Jrm2007 (talk) 23:45, 1 November 2013 (UTC)

4 diagrams (could be useful)
(with google translator help) Hallo, I did this job for Italian Graphic Lab, I've also prepared an english version of them, if somebody wants to take a look at them... in the future they could become useful somewere. File:Supernovae as initial mass-metallicity.svg File:Remnants of single massive stars.svg File:Collapsar as initial mass-metallicity.svg File:Jet supernovae as initial mass-metallicity.svg -- Fulvio 314  10:52, 28 November 2013 (UTC)

SuperNova Dust
A news item about dust produced by a supernova, for the authors if they think the information is valuable.Jcardazzi (talk) 16:22, 20 March 2015 (UTC)jcardazzi http://news.cornell.edu/stories/2015/03/milky-ways-center-unveils-supernova-dust-factory

Consideration
"A supernova is a rare astronomical event that occurs during the last stellar evolutionary stages of a massive star's life..."

Wait a minute, how about type Ia supernovae? They are different. SkyFlubbler (talk) 14:14, 18 January 2016 (UTC)

Actually, the white dwarf in SNIa is in the last stellar evolutionary stages of a massive star's life. As the white dwarf is near 1.4 solar masses, its progenitor must have been about 6 to 8 solar masses. The progenitor has mostly ended its life. Technical not perhaps "massive", but as an introductory sentence, and is often stated similarly elsewhere in astronomical sources. I.e. Jacquiline Mitton in "The Penguin Dictionary of Astronomy" says "A supernova explosion occurs when an evolved massive star has exhausted its nuclear fuel." The text following the first statement is formally explained anyway. Arianewiki1 (talk) 10:21, 19 January 2016 (UTC)

Introductory sentence
"A supernova is an astronomical event that occurs during the last stellar evolutionary stages of a massive star's life, whose dramatic and catastrophic destruction is marked by one final titanic explosion."

Modifications to this sentence is quite difficult, mostly because the causes of the event and also the remnants are diverse.

It address the truth that:


 * 1) Destruction of a white dwarf or massive/supermassive star are at the end of the life of the star.
 * 2) The final event occurs very quickly. I.e. Massive stars less than a second or white dwarf where the collapsing shockwave is slightly faster c.0.4 seconds.
 * 3) It is catastrophic because it destroys the star
 * 4) The energy created is titanic
 * 5) The supernova remnant appear as an explosion.

Saying "A supernova is an astronomical event that occurs at the end of the life of certain stars, when they are completely destroyed in a catastrophic explosion." is incorrect.


 * 1) Only massive stars can go supernovae. Those that are white dwarfs near the Chandrasaker limit are close to 1.4 Solar masses, but the original progenitor was massive star.
 * 2) Supernovae can produce neutron stars / pulsars, hence such stars are not necessarily completely destroyed.

(This is all explained in Paragraph 5) The introductory sentence is supposed to accurately reflect the definition of a supernova. The structure as it exists precisely does this, and considers the diversity of different types of supernova.

Moreover, Lithopsian statement to change this by saying "Replace factually incorrect lead sentence (see talk page))" is already incorrect, just by ignoring neutron/pulsar are generated by supernova.

Also changing edits by saying " (Remove fluff sentence originating from non-neutral editor (User:WAFred))" and "remove a rather speculative section apparently written by an involved party", is plainly provocative and ignores WP:GF. If you have proof or evidence of a "non-neutral editor" or "an involved party", it should appear on this talkpage. Who is the involved party? Seemingly claiming some unknown 'User:WAFred' (who doesn't exist) as justification is plainly unacceptable. Arianewiki1 (talk) 18:40, 12 April 2016 (UTC)


 * NOTE: Re-reading the complaint that "Remove fluff sentence originating from non-neutral editor (User:WAFred))" assigned to this edit in question can be construed as a derogatory comment under WP:PA. Editors should not avoid WP:CIV. Also making ANY kind of disparaging remarks about other editors without proof with no justification or reason is clearly unacceptable. Arianewiki1 (talk) 19:10, 12 April 2016 (UTC)

Type II energy output
Why does one table say type II produces 1 foe but another table says 100 foe? Asgrrr (talk) 20:25, 21 May 2016 (UTC)

Nevermind, first is without neutrino energy, right? Asgrrr (talk) 20:27, 21 May 2016 (UTC)

capital T required by Type Ia supernovae ?
In the article, both "Type Ia" and "type Ia" are found within sentences. — Preceding unsigned comment added by 217.186.217.219 (talk) 21:22, 13 June 2016 (UTC)

Type Ia is correct. Thanks for the heads-up! Arianewiki1 (talk) 03:11, 14 June 2016 (UTC)

Chinese and arab texts
Only the Chinese text is specific. The Arab text is not agreed upon, as is clearly mentioned in the cited article. Furthermore the article cited is not a primary source, as it is simply restating one possibility from someone who helped them. This error should be addressed.

We can be certain of the Chinese example, but the Arab example is dubious at best, and calling it "islamic" is also incorrect. — Preceding unsigned comment added by 180.54.78.138 (talk) 20:17, 30 November 2016 (UTC)

Introduction Explanation (again)
"A supernova is an astronomical event that occurs during the last stellar evolutionary stages of a massive star's life, whose dramatic and catastrophic destruction is marked by one final titanic explosion."

Modifications to this sentence is quite difficult, mostly because the causes of the event and also the remnants are diverse.

It address the truth that:


 * 1) Destruction of a white dwarf or massive/supermassive star are at the end of the life of the star.
 * 2) The final event occurs very quickly. I.e. Massive stars less than a second or white dwarf where the collapsing shockwave is slightly faster c.0.4 seconds.
 * 3) It is catastrophic because it destroys the star
 * 4) The energy created is titanic
 * 5) The supernova remnant appear as an explosion.

Also noted
 * 1) Only massive stars can go supernovae. Those that are white dwarfs near the Chandrasaker limit are close to 1.4 Solar masses, but the original progenitor was massive star.
 * 2) Supernovae can produce neutron stars / pulsars, hence such stars are not necessarily completely destroyed.

(This is all explained in Paragraph 5)

Actually too, the white dwarf in SNIa is in the last stellar evolutionary stages of a massive star's life. As the white dwarf is near 1.4 solar masses, its progenitor must have been about 6 to 8 solar masses. The progenitor has mostly ended its life. Technical not perhaps "massive", but as an introductory sentence, and is often stated similarly elsewhere in astronomical sources. I.e. Jacqueline Mitton in "The Penguin Dictionary of Astronomy" says "A supernova explosion occurs when an evolved massive star has exhausted its nuclear fuel." The text following the first statement is formally later explained anyway.

Sentence 2

"This causes the sudden appearance of a "new" bright star, before slowly fading from sight over several weeks or months."

After describing what a SNe the text describes what they observationally appear like. They appear suddenly in a few days, but can fade from view quickly or slowly depending on their distance and type.

If you add that they explode in a few seconds (which varying anyway depending on the scenerio), then you also need to explain how and why, which just confuses readers. Sure the true star collapse is fast, but visually is rises between half-a-day and several days. In truth it explains in general terms what is view when a SN explodes.

Also the Introduction is a base summary, and summaries what SNe in the least amount of words. (Considering the history of this page, the first paragraph has always been modified, and to avoid unnecessary changes.) Much time was spent formulating this paragraph and IMO you'll need to explain any modifications.

As for "...important pre-decay time-scales", means exactly what here? Important to whom? (It is discussed later anyway.) Is a supernova when the star collapses or when the expanding shell becomes bright enough to be able to see it, which is near its maximum light? (Former takes seconds, the latter takes days. Word "suddenly" is a compromise that covers all.)

If you wish to change this, you must discuss this here, and also gain consensus to do so.

Q. The real question are these statements factual? Thanks. 14:05, 2 February 2017 (UTC)

SN 2013fs (PTF13dqy) early observation
Can an editor knowledgeable about astronomy take a look at SN 2013fs (PTF13dqy). Given the early observation data of this event SN 2013fs might deserve a chapter in this article or even a page. My knowledge of astronomy is a bit rusty, and never was that good. I have referenced my recent changes and also found more information here.
 * It is better suited for Type II supernova article. Ruslik_ Zero 20:51, 15 February 2017 (UTC)


 * I'd say even better-suited for its own article. A single supernova is unlikely to change what needs to be said in a catch-all article except as a passing mention. The authors of papers about that supernova (or others) inevitably think it changes the world, but only time will tell if that is true. See WP:TOOSOON. Lithopsian (talk) 22:18, 15 February 2017 (UTC)


 * It looks like someone created an article at 09:28, 15 February 2017. SN 2013fs

147.148.251.204 (talk) 00:20, 16 February 2017 (UTC)

Novae and Supernova
This article says in the Introduction: "Supernovae are more energetic than novae. In Latin, nova means "new", referring astronomically to what appears to be a temporary new bright star. Adding the prefix "super-" distinguishes supernovae from ordinary novae, which are far less luminous. The word supernova was coined by Walter Baade and Fritz Zwicky in 1931."

However, Elenceq want to changed this, by removing everything but the first line to a new section on "Etymology."

The original should stay as written because it explains, qualifies and reinforces the differences between novae and supernovae, and the link to novae. The introduction ought to summarise the main document, which is further explained under section Discovery Secondly, this text stablises the article from contentious edits, where some confusion has occurred or was expressed in the past betwee novae and supernnovae.

I see not need to change this at all. Seeking consensus to agree. Arianewiki1 23:11, 28 September 2017 (UTC)


 * There should be an "Etymology" section - because many readers like myself want to know the ORIGIN of the term. Knowing the genesis of a term or name is important to some of us, and this is common practice throughout Wikipedia.  Why not explain where and how the term / name originated??? 98.194.39.86 (talk) 22:04, 9 June 2018 (UTC)

Hmmmm - it might be a gravitational lens or?
A gravitational lens has the same effekt to an observer not able to resolve objects with less than one arcsecond distance like all abservers without telescope. I think many supernovae in the past might well be gravitational lenses. 84.118.82.226 (talk) 14:01, 2 February 2018 (UTC)
 * No. Not possible. It doesn't work that way. Arianewiki1 (talk) 01:15, 3 February 2018 (UTC)
 * Hmmmmm - why not? — Preceding unsigned comment added by 84.118.82.226 (talk) 12:08, 3 February 2018 (UTC)
 * Gravitational lenses don't "focus" properly. They produce lines, arcs, or multiple images, not a single brighter point-like image.  There are examples of gravitational lenses of supernovae, but they are easily recognised for what they are.  Start reading here for fun, and here to really learn how it works.  Lithopsian (talk) 20:16, 3 February 2018 (UTC)

First sentence
"A supernova is a rare astronomical event that occurs during the last stellar evolutionary stages of a massive star's life...": this definition might be suitable for type II SNe but definitely not for type Ia. Ia progenitors are still unknown (plural is used on purpose). This is misleading and should be reworked.


 * Indeed the progenitor systems of type Ia SNe are still debated. It is known however, that they involve a white dwarf – and so are not the death of a massive star. So this sentence was just plain wrong. Tried to fix it. 134.160.214.17 (talk) 08:53, 6 June 2018 (UTC)


 * Isn't there a place where 'astro-people' can go to discuss stars in scientific terms? An encyclopedia isn't meant to be a graduate level textbook on the subject.  Rather, it should be a place where common people can go to quickly find out what something is.  Simple, in lay terms.  I am SO disappointed in what WP has become over the last 10 years.  It has morphed into a place where subject-matter "experts" can spew out technobabble and fight over competing "theories", while the rest of us intellectually inferior types can merely look on and try to comprehend what all the fuss is about.  Being an engineer myself, I view this is as a form of snobbery that one might expect to find in academia, but not in a public encyclopedia.  Why must editors continually over-complicate definitions and throw around terminology that you KNOW the average person doesn't understand?  As it stands, one would have to be an expert on stellar physics to even read this article, much less use it for anything.  And that means, in very simple terms, that it is USELESS to the vast majority of readers who find it.  Again, I repeat... Useless to the average reader.  Even when I wrote for NASA as a systems architect, I was told to keep it at a 9th grade level.  Because not everyone is a specialist on everything.  Think about that before continuing with your edits, please.  Reserve those discussions for publications or academic frat meetings - and leave the rest of us out of it. Finally, please note that there is such a thing as "good enough" for general use.  Not every topic needs to be perpetually beaten to death in the vain search of perfect accuracy.  Perfection is the enemy of Done.  Right?  98.194.39.86 (talk) 21:58, 9 June 2018 (UTC)

Not nova
As above (at First sentence, and Introduction Explanation (again) and probably more), I’d really like a “9th grade level” definition of nova, supernova, and hypernova.

Alternatively; how do you ask a question like;
 * “What is it called when a dying star [... or what?] explodes”
 * so that the answer is only one of nova, supernova, or hypernova.

MBG02 (talk) 04:10, 30 November 2018 (UTC)


 * Nova means new. It was given to what people thought were 'new' stars, because they never saw them before. But the real cause isn't that the star is new, it's that an existing star increased in brightness for some reason, and became visible. What exactly to call an dying star that explodes depends on what kind of star it was, and why it exploded, but most of those things will be novas of some kind. I hope that helps. Headbomb {t · c · p · b} 22:23, 30 November 2018 (UTC)

Initial Paragraph
I've just restored the first paragraph back to the original accepted version. The need is due to likely missed vandalism by Tsalina308 on 28 September 2018 here. here and here. They've only made three edits This was again changed by an IP 204.48.98.237 here on 23 October 2018, and has survived to now.

There should not be any controversy in reverting the series of edits. Arianewiki1 (talk) 04:17, 29 May 2019 (UTC)

The "bulk" of all elements?
In the body of the article it is said that supernovae are a "major source of elements heavier than nitrogen". That has been my understanding. But with this edit:  restored the following sentence into the lede:

"Supernovae create, fuse and eject the bulk of the chemical elements produced by nucleosynthesis."

Is this true? No qualification is given for elements heavier than nitrogen, so one can interpret Arianewiki1's sentence as meaning that the bulk of all elements are the product of supernovae. A further concern is the word "bulk". What is meant by this? The number of atoms produced by nucleosynthesis or their total mass? Anyway, I think Arianewiki1's sentence either needs to be fixed or removed. Thank you. Attic Salt (talk) 13:09, 13 June 2019 (UTC)


 * The statement isn't entirely correct, for a few reasons. One reason is that alpha elements are created by fusion inside of massive stars but then ejected by supernova explosions, so it's not correct to say that the supernovae "create" or "fuse" those particular elements. On the other hand, iron peak elements are largely produced and ejected in Type Ia supernova explosions. So the situation is different for different groups of elements, and for different types of supernovae, and requires a somewhat more lengthy explanation. Aldebarium (talk) 19:43, 13 June 2019 (UTC)
 * Thanks. I was under the impression that most of the helium, lithium, etc. up to something like iron (this article says it is nitrogen) are produced by nucleosynthesis inside of stars, not in supernovae, hence my concern about the sentence quoted above. Attic Salt (talk) 19:55, 13 June 2019 (UTC)


 * The revert was likely vandalism by an IP, because they state: "Deleting statements that attribute bulk of nucleosynthesis to supernovae as this is now thought to primarily take place through neutron star collisions". This just isn't true. The rest of Attic Salt's assertions are not true, as I neither support nor condone the statement. e,g. It is not Arianewiki1 sentence.  The edit with 2 cites was added by  in November 2015 here, actually. Reading Supernova nucleosynthesis perhaps might help you, where it says: "...suggesting that the expected shock-wave nucleosynthesis is an essential component of supernova nucleosynthesis."
 * The reference source is "Galactic Chemical Evolution: Hydrogen through Zinc" tends to support the statement. Boron to nitrogen is generate during the life of the star by nucleosynthesis as these elements appear is SN spectra. They are also generated in the shockwave, except for perhaps Lithium or Beryllium, which maybe formed via Spallation. (Attic Salt: Again. If you don't understand something, then leave it alone. Also Wikipedia is not an educational resource.)
 * Blaming me for what others write is deplorable, especially without even bothering to look for any evidence to say something is true. Again Attic Salt, you've been repeatably told to stop targeting me, and leave me and my edits alone. Do so. Utter rudeness will be the next step. OK. Arianewiki1 (talk) 00:19, 14 June 2019 (UTC)
 * . Any thoughts of a retraction of these false accusations? Arianewiki1 (talk) 22:58, 14 June 2019 (UTC)
 * . Any thoughts of a retraction of these false accusations? Arianewiki1 (talk) 22:49, 16 June 2019 (UTC)
 * Note: the previous revision changed my text above (I assume inadvertently); I just reverted it back to what I wrote earlier today. Aldebarium (talk) 01:11, 14 June 2019 (UTC)
 * I did that as a honest mistake. Sorry. Arianewiki1 (talk) 03:23, 14 June 2019 (UTC)
 * No problem. In any case, I'll try to think about how to expand that statement about nucleosynthesis into something that's more generally applicable to different element groups and different types of supernovae, while still keeping it brief enough to be in the lead section- it's probably a bit of a challenge to find the right balance. Aldebarium (talk) 10:21, 14 June 2019 (UTC)

One possible point of confusion, I've been assuming that supernova nucleosynthesis refers specifically to nucleosynthesis occurring during the supernova phase of stellar evolution. While stellar nucleosynthesis refers to nucleosynthesis in stars, even those that might go supernova, but before the supernova phase. Comments? Attic Salt (talk) 14:53, 16 June 2019 (UTC)

Also note that this source:, makes it clear that supernova nucleosynthesis only contributes the "bulk of the heavy elements (A ≳ 20) observed in nature", very different from the unqualified statement given in the lede that "supernovae create, fuse and eject the bulk of the chemical elements produced by nucleosynthesis." Hence, my concern. Attic Salt (talk) 15:04, 16 June 2019 (UTC)
 * I've added this source to the article, and used a more accurate sentence already given in the body of the article. Attic Salt (talk) 15:28, 16 June 2019 (UTC)
 * Please stop editing this page. There is enough supposition above that shows little understand of the subject at hand. The core collapse and bounce make the heavier elements, the shockwave makes the lighter elements undergo nucleosynthesis. The only difference between supernova ejection and stellar superwinds is only in the ejected nebula's composition and their abundances.
 * This edit based on what being said is unfounded and likely OR or possibly added disruptively. e.g. The references do not mention nitrogen in the context presented. The first reference doesn't even mention nitrogen! (I gave you the link explaining it, but do this?) I do think they might have meant the carbon-oxygen-nitrogen cycle, but the sources don't say that ether. Another option is after they read about the effects on Earth for a neaby SN event and the creation of nitrous oxide: but that isn't in any related given reference. I removed the nitrogen that later appears in the text too, and replaced it with an uncontroversial option that is true.  Arianewiki1 (talk) 08:05, 17 June 2019 (UTC)

I'd like to make a suggestion that I hope will be helpful for this discussion. There is an exceptionally clear and well written review article on the topic of stellar and supernova nucleosynthesis and the origin of the elements that was published in Science (journal) a few months ago. It is up to date and explains all of these issues very well, and it would be very valuable as a reference for the Supernova article. I would highly recommend that anyone interested in pursuing this discussion further should read this article as it will go a long way toward clarifying which elements are formed through which processes and in what kinds of objects or events. Unfortunately the article is behind the AAAS paywall, but if you have access or can get a hold of the article, this will be very useful, and I hope that it may be helpful in reaching consensus as to what should be stated in the Supernova article. Here is the link to the Science article. (DOI: 10.1126/science.aau9540) Aldebarium (talk) 15:13, 17 June 2019 (UTC)

Stellar nucleosynthesis vs supernova nucleosynthesis
As I understand it, supernova nucleosynthesis refers specifically to nucleosynthesis occurring during the supernova phase of stellar evolution. While stellar nucleosynthesis refers to nucleosynthesis in stars, even in massive stars before they enter the supernova phase. This interpretation of terminology is borne out in reading the article by Jennifer Johnson (Science Magazine, already cited in Supernova). See, for example, bottom of page 2 of her article, where she says: "... supernovae enrich the Universe in three ways. First, they eject the products of nucleosynthesis built up over the star’s lifetime. Most carbon, oxygen, and magnesium, for example, are made before the core collapse, and the explosion simply distributes these elements into space. Second, the extreme temperatures and densities caused by the shock wave drive additional nucleosynthesis. In particular, the iron ejected by core-collapse supernovae comes not from the core but from explosive burning of material in the silicon shell during the supernova. Last, the additional shocks that occur as the ejected material plows into surrounding ambient gas accelerates some particles to close to the speed of light, making cosmic rays."

In light of this, then, I think we need to be careful with sentences like "Supernovae are the major source of elements heavier than nitrogen." or "Supernovae create, fuse and eject the bulk of the chemical elements produced by nucleosynthesis." The supernovae phase of stellar evolution does, yes, disperse elements inside of a star, but the production of many of those elements is not (apparently) what we would call "supernova nucleosynthesis" -- it is "stellar nucleosynthesis". In that regard, I note that Johnson is very careful with her words. The periodic table shown in her Figure 1 is labeled as "Nucleosynthetic sources of elements in the Solar System." That is, after supernova dispersal. So, labels on individual elements as coming from "exploding massive stars" includes those created both by pre-supernova steallar nucleosynthesis and, also, supernova nucleosynthesis.

Attic Salt (talk) 13:07, 21 June 2019 (UTC)


 * "Exploding white dwarfs" are supernovae too. We, and the article, tends to forget them, but they actually contribute more of the iron-peak elements than do core collapse supernovae.  Another thing to remember is that models of supernovae aren't actually very good at reproducing the proportions of heavy elements that we observe, so we should take it all with a pinch of salt.  Another point we could perhaps make clearer (or just leave for supernova nucleosynthesis?) is the absolute and relative yields of many of these elements.  For example, core collapse supernovae eject a lot of carbon - more than any other element except hydrogen, helium, usually oxygen, and sometimes neon - partly because the outer layers of the progenitors are carbon-rich and readily ejected.  However, AGB stars produce even more carbon, so supernovae are responsible for only a minority of the carbon in the universe.  Likewise, the vast bulk of material ejected by a core collapse supernova is hydrogen and helium, the hydrogen unprocessed material from the big bang and the helium partially from the big bang and partially from fusion, but minuscule quantities compared to overall levels present throughout the universe ever since the big bang.  On the other hand type Ia supernovae produce very little hydrogen or helium. Lithopsian (talk) 20:20, 21 June 2019 (UTC)


 * Attic Salt. Hands in the air. Reading the response above confirms why you should not be editing this article. Saying "Stars that eventually explode as supernovae are a major source of elements heavier than nitrogen in the interstellar medium…" other than the appalling sentence structure, it is mostly wrong. e,g, The definition of a exploding star is a supernova. So just say supernova. Saying: "a major source of elements heavier than nitrogen", but the article (and cite) says: "Stars that eventually explode as supernovae are a major source of elements from oxygen through to at least rubidium." "nitrogen" "above nitrogen" is a fiction that you have made up as original research. (Worst this has the same point has been made by Lithopsian, but you won't listen. I agree with the summary of Lithopsian above, and suggest the a note might be added to the article might help. After reading this, you also now do not have consensus at all.)
 * The Introduction is meant to be a summary of the article Lead, and because of the complexity of the subject, the text has to be a general compromise. You don't seem to care about that, and are just 'digging in the heels' to be difficult as possible. It is called sanction gaming, and is against policy. Arianewiki1 (talk) 01:25, 22 June 2019 (UTC)

I changed "stars that eventually explode as supernovae" to "supernovae", but added "in the interstellar medium" since some elements are created before the supernova phase. I think this accommodates both Lithopsian's point and Arianewiki1's unhappiness with the sentence's clunkiness. I ask Arianewiki1 to consider the quote from Johnson, given above, in which it is explained that supernovae disperse elements created in the star prior to exploding. The issue of "major source of elements from oxygen through to at least rubidium" can be seen in the periodic table in the article and is Figure 1 in Johnson. Thanks, Attic Salt (talk) 12:49, 22 June 2019 (UTC)

By the way, I didn't make up any fiction about nitrogen. That was there (in the body of the article) before I started editing this page. Still, I don't see anything wrong with it. Nitrogen is one atomic number below oxygen, and the periodic table in the article makes it pretty clear that supernovae contribute lots of elemental abundance above nitrogen. I honestly don't see why this is controversial. Thanks, Attic Salt (talk) 18:41, 22 June 2019 (UTC)


 * This a joke response, right? The statement "I honestly don't see why this is controversial." Could it possibly be because it is just wrong?
 * Let's see. You did these reverts,, , claiming some source which does not say what you claim, but still say: "I didn't make up any fiction about nitrogen. That was there (in the body of the article) before I started editing this page. Still, I don't see anything wrong with it. Nitrogen is one atomic number below oxygen, and the periodic table in the article makes it pretty clear that supernovae contribute lots of elemental abundance above nitrogen." You've been asked where it says in the article "about nitrogen" or "nitrogen" appears in the article. (It doesn't, does it?) Evidence says you've added this on a total fiction, especially because the two linked sourced don't say this and Johnston article wasn't then linked.  (The Francois (2004) cite in the article didn't even mention Nitrogen (except by stellar winds for 14N).
 * The likely reason why this was added was because of the abstract statement "We computed the evolution of the abundances of O, Mg, Si, Ca, K, Ti, Sc, Ni, Mn, Co, Fe and Zn in the Milky Way." This was the part of their study, but it does not say that other supernova abundances exist. But you then added another Truran (1977) reference to try and justify the change. After Lithopsian's disruptive edit here and adding the Johnson cite here. Looking at the new image of the Periodic Table, you followed this with`this edit.. saying: "The Johnson article makes it clear that this should be qualified as "about nitrogen" given her Figure 1."(yet you say above that "") THE QUOTE DOES NOT SAY WHAT YOU CLAIM, and worst "the quote from Johnson" doesn't appear in that article at all. Yet you still defend it!
 * Evidence suggest you are pushing a POV and manufacturing stuff up to hold onto the your 'wrong' opinion. Evidence says this is original research. What stinks is that on top of this, you accuse me of : "...so one can interpret Arianewiki1's sentence as meaning..." "Anyway, I think Arianewiki1's sentence either needs to be fixed or removed" (Worst you refuse to retract the false accusation.) I never added this statement (it was WAFred) I reverted the edit because the reasoning by the IP 69.229.4.161 was incorrect.
 * But the final insult was these five successive edits adding cites that don't even say what you claim.
 * You have been advised of what the central problem is with the current text by here,  to generalise and/or improve the statement. But that doesn't matter either.
 * But even if this is acceptable, it is clear that you targeted this part of this only only because of my revert of an IP edit, and you thought it was a chance "to nail me" on some esoteric point just to frustrate the editing process. You were pushed on by Lithopsian pointy edits here and here, especially when they claim "…and of course complete rubbish." (Then to make sure of this, they then delete the cites, making certain the burn their bridges behind them on a unrelated pretext.)
 * This kind of tactical behaviour is not the only time (over several ANIs now).
 * Even when pointed out about sanction gaming, the latest series of edits and above continue this same kind of gaming. We have now reached the stage of getting an ANI requesting a topic ban. Arianewiki1 (talk) 03:06, 23 June 2019 (UTC)
 * First of all, I am not the originator of the word "nitrogen" that was, once, mentioned in the article. My first edit on the Supernova article was on June 16, 2019:, when I added a label to a citation for the mention of "nitrogen" -- the mention of "nitrogen" was already there and, in fact, had been there for a least a year before I came along, see, for example, this version of the article (you can do a word search for "nitrogen"). I hope it is now clear that I didn't do any "original research" as you have suggested so many times.
 * First of all, I am not the originator of the word "nitrogen" that was, once, mentioned in the article. My first edit on the Supernova article was on June 16, 2019:, when I added a label to a citation for the mention of "nitrogen" -- the mention of "nitrogen" was already there and, in fact, had been there for a least a year before I came along, see, for example, this version of the article (you can do a word search for "nitrogen"). I hope it is now clear that I didn't do any "original research" as you have suggested so many times.


 * Second, your concern with whether or not the Johnson source says "about nitrogen" appears to be a misinterpretation of a summary I provided for this edit:, where I added the word "about" to the article in front of the word "nitrogen". I was not giving, as you suggest, a "quote from Johnson" -- I've never said "quote from Johnson". My edit summary was simply a summary of what I wrote. The Johnson source shows (her Figure 1) that supernova contribute a smaller proportion of elements lighter than nitrogen, so I thought it worthwhile to qualify the sentence in the article with the word "about". I hope that clarifies things.


 * Third, I apologise for referring to a sentence as "Arianewiki1's sentence". You had restored a sentence to the Supernova article with this edit . Unfortunately, you did not provide any summary with your edit, so I simply assumed you supported inclusion of this sentence in the article. You might ask yourself whether or not any of this rises to the level of the harassment you've piled onto my talk page:.


 * I don't imagine my responding to your points is going to help this situation. Still, I know I needed to give it a try. Attic Salt (talk) 13:01, 23 June 2019 (UTC)


 * Simply isn't true. You added this in these five edits here and added a cite that does not say what is have claimed.
 * As for apologies, upon this edit and saying: "Oh, I see, this is a revert.". Well you should have fully redacted the incorrect text, then do the right thing and openly admit the mistake. (You were asked to do so multiple times, but ignored the request. It is the definition of 'bad faith'. Any reason?  I believe you left it there to make me look like a disruptive editor (yet again), 'mudding the waters' to hide away the 'gaming'. In this example, all this could have been avoided by just asking me for a reason for the revert.  Instead you saw an opportunity.
 * Perhaps, you again better take my advice and leave my edits alone. Sure. Fix minor errors, but don't change context. Also stop revert everything on one minor trivial point. e,g. This reverted edit here and all made within a minute of time. (There is not excuse for this kind of editing behaviour, and it validates my complaints. Yet you dismissively say: "I honestly don't see why this is controversial."? How should I feel then?)
 * The rest written above is dodging the fact sanction gaming, and you were caught out doing it. Again you are responsible for your edits, and you persisted defending a POV by reverts and doing further WP:OR to justify that position - even after being told why it was wrong. This is against policy.
 * You still repeatably keep wrongly saying and defending: "The Johnson source shows (her Figure 1) that supernova contribute a smaller proportion of elements lighter than nitrogen." It is not true because the source not say this, It is your own opinion made by you looking at some graphic figure, making it original research. That is against policy.
 * As for: "I don't imagine my responding to your points is going to help this situation." Please. Go right ahead. (In the latest ANI, we're all ears.) Arianewiki1 (talk) 04:52, 24 June 2019 (UTC)

Extended-confirmed-protected edit request
There has been many problems or various problems with recent edits, especially ambiguous reverts. I have recently made a new version, that meets discussions on the talkpage, but this needs better evaluation regarding further changes. It might not be perfect, but it would solve the potential of edit warring or multiple reverts. This article has been mostly stable for sometime, and as a Good article ultimately needs protection. Arianewiki1 (talk) 07:32, 23 June 2019 (UTC)
 * Full-protection-unlocked.svg Not done: According to the page's protection level you should be able to edit the page yourself. If you seem to be unable to, please reopen the request with further details. —&thinsp;JJMC89&thinsp; (T·C) 07:50, 23 June 2019 (UTC)
 * If you want to change page protection levels, see WP:RFPP. Do note however that neither ECP nor semi protection are generally applied preemptively for ordinary articles, even good or featured articles. (TFA is sort of an exception.) Note that neither ECP or semiprotection would have much effect on edit warring or multiple reverts here. Since 13 June, there was a single IP edit quickly reverted [//en.wikipedia.org/w/index.php?title=Supernova&diff=902828405&oldid=902818166]. Otherwise every single editor involved is extended confirmed. Hopefully there is no confusion over the difference between ECP and a 1RR page restriction. Full protection may be used when there is ongoing edit warring involving extended confirmed editors but the alternative is to just block those edit warring so the best solution if you're involved is to stop edit warring. BTW this article is technically still WP:Featured article as it has not been demoted. Nil Einne (talk) 03:03, 24 June 2019 (UTC)

Initial Paragraph Issues Further Explained
The Introduction to this 'featured article' is a base summary, and summaries what SNe are in the least amount of words. It is perhaps imperfect, but it has been stable for sometime and is a reasonable compromise. (Considering the long history of this page, the first paragraph has always been modified, and needs unnecessary changes to avoid more problems. e.g. As this restored edit here explained under this section.)

The true cause of supernovae is obviously complex, which is technically just the rare appearance of a type of 'new' bright star. It also is defined as having several processes in a series of events that occurs prior to seeing this 'new' star. e.g. Collapse of core, bounce, then the outburst of the expanding shockwave the quickly brightens then fades over time. (Further explained in 4th paragraph.) It is not just an 'explosion'. (The word 'final' explains the end of the process.)

Also, whilst a type of supernova (Type I) is caused by a heavy white dwarf, the text before this describes "...that occurs during the last stages of the life of a massive star..." The point is that the progenitor of the white dwarf was once a massive star (c. 6 to 8 solar masses), so that this sentence is not contradictory in the broader sense. Saying 'white dwarf' here is clearly unnecessary, and is again further explained in the 4th paragraph. This isn't an arbitrary selection of words and it changes the context.

Much time has been spent by several editors formulating this paragraph and IMO there needs to be a better or fuller explanation for any further modifications.

Further changes should be again discussed on this talkpage if gaining a newer consensus were is required. Arianewiki1 (talk) 01:39, 28 June 2019 (UTC)


 * in this series of edits has made reasonable changes here. However, this change I think is important to fix because as it usefully removes any difficult complications in having to explain the scenarios between the types of supernova, yet still explain differentiation between kilonovae or novae. e.g. Novae too are caused by white dwarfs.
 * modifications here has changed the context, as previously discussed. Saying "Unexplained (no edit summary) removal of “white dwarf”, from lede but which is discussed in body of this article.)" Yet this has been discussed previously on this article's talkpage as stated, and is also already further expanded in the Introduction (lede) within the 4th paragraph.
 * Attic Salt is yet again reminded that edit summaries are not a requirement to edit, and using revert edits (rv) is no justification to revert. It is against policy. Repeatably doing this is now violating rehash and wikihounding, all seemingly done just to cause distress to another editor in the hope of 'nailing them' on some esoteric point. They are also openly reminded of the WP:BRD policy, especially if there is consensus in the community against some specific change you'd like to make. Please break away from this unpleasant repeated cycle of pointy (Do not disrupt Wikipedia to illustrate a point) behaviour. Arianewiki1 (talk) 03:02, 28 June 2019 (UTC)
 * Oh. Good. God. You are seriously defending this broken-ass edit to the lede of a FA, with its faulty capitalization and punctuation and (due to the lack of an edit summary) complete lack of context that might have otherwise helped another editor figure out what the hell you were trying to do? Of course it was reverted. Cleaning up your messes is not harassment, and your repeated false accusations of such are grounds for a block or ban. You don't own your own edits, much less this page, so you should have no reason to expect that anyone, ever, is going to give a second's thought to your requests for others to not modify your work.
 * It doesn't appear there is a stable version despite Arianewiki1's self-reference above. I am fine with removing "white dwarf" per this section; "whose dramatic and catastrophic destruction" is terrible writing (a star is not a "who" and the adjectives are hopelessly repetitive); "final" is a useless word; "from sight" is imprecise; and I prefer Arianewiki1's phrasing of "over several weeks or months". So how about ? VQuakr (talk) 05:07, 28 June 2019 (UTC)


 * No. I'm not god. Yet what is truly terrible is your ranting response above. Little of it makes sense, and clearly has some retributive motive of some personal vendetta because of some ridiculous stance you have over edit summaries. Your problem. Yet by complaining of "...complete lack of context that might have otherwise helped another editor figure out what the hell you were trying to do?" means what exactly? I write a few lengthy edit summaries, add this thread to explain why (including its history), and the context is explained and previously discussed several times throughout this talkpage, with a similar version has survived since December 2015. It was gained via consensus, and has been logically explained (Read some of the previous discussions, please.) Yet this is not good enough for you?
 * It is 'dramatic' on astronomical timescales.
 * It is 'catastrophic' because it destroys the star, but may or may not leave a remnant.
 * 'Final' is not useless, because nova can repeat brightening while supernova can do this only once.


 * Me saying "It is perhaps imperfect, but it has been stable for sometime and is a reasonable compromise." or "Further changes should be again discussed on this talkpage if gaining a newer consensus is required." can hardly be construed as OWN at all.


 * Making false accusations but then make new false accusations yourself is plainly hypocrisy. Arianewiki1 (talk) 08:37, 28 June 2019 (UTC)


 * Sure, "you again better take my advice and leave my edits alone" is totally not an ownership red flag. You are not addressing the issue. I am not concerned with the accuracy of each individual word, I am concerned with the quality of the English language sentence you end up with when you mash together a bunch of imprecise and redundant adjectives. Does anyone else think "whose dramatic and catastrophic destruction" is appropriate text for the lede of a science article? VQuakr (talk) 15:59, 28 June 2019 (UTC)


 * Nice potshot. The real red flag here is going on the attack without any provocation. As for Attic Salt, are you now his mother or protector? I've asked them to leave me and my edits alone because of persistent and repeated sanction gaming. They keep following me and are plainly targeting my edits when they been asked to stop doing it. That is the bigger problem. It is not about WP:OWN at all, it is because they just cannot back off. They want me to stay away from their talkpage and leave them alone, yet they continue on with these pointy surgical strikes.
 * Editing also takes some competence. which by the 'white dwarf' addition they clearly don't see the problem in why this is wrong, saying "This really is ridiculous. The article discusses SN from both massive stars and white dwarfs. So, the definining first sentence can't mention one without mentioning the other.".
 * As for the rest, did you even read the initial text above?
 * Still the point is:
 * How fast do stars convert into supernovae?
 * How much of the star remains after it goes supernova?
 * None of that is mentioned in the 1st paragraph. Is it important to say or not? That is why consensus needs to be gained, and not carte blanche rv because you disagree or think something is awkward. Considering the original disputed version survived four years in a featured article makes your assertion fairly inept.
 * Even more confusing you've said "... am fine with removing "white dwarf" per this section .", then say "Rmv "white dwarf" per Arianewiki1's comment on talk", but now say to Attic Salt below "Works for me. " So which is it, or are you now just sitting on the fence? (After this rv here, I assume then this is OK? Arianewiki1 (talk) 02:18, 29 June 2019 (UTC)


 * A bit more of the phrase that Arianewiki1 wants: "... whose dramatic and catastrophic destruction is marked by a final titanic explosion". This is overdoing it. We might consider the advice of Mark Twain: "As to the Adjective: when in doubt, strike it out." Attic Salt (talk) 19:05, 28 June 2019 (UTC)
 * The implication that I "want" this statement is false, as article editing doesn't work this way.
 * If you can improve it do so, but don't change context nor make statements that are already true into something that is false. e.g. Is the statement "... whose dramatic and catastrophic destruction is marked by a final titanic explosion" or is "during the last stages of the life of a massive star or white dwarf, the destruction of which is marked by a titanic explosion." true or false? Statements need to have a epistemic quality of being "ontologically superior" to opinion or interpretation. Also science topics need to have factual conclusions that are influenced by history and consensus, rather than a strictly systematic methodology.
 * Here, your view is not the only one, and you need to work towards gaining a new consensus not just imposing it. Ironically paraphrasing Shakespeare: "The fault, is not in our stars, but in ourselves." Arianewiki1 (talk) 02:43, 29 June 2019 (UTC)

Since the article discusses SN from both massive stars and white dwarfs, the defining first sentence can't mention one without mentioning the other, otherwise the reader will be confused. Attic Salt (talk) 13:19, 28 June 2019 (UTC)


 * Works for me. VQuakr (talk) 15:59, 28 June 2019 (UTC)


 * Umm… As long as you realise nearly all massive stars go supernovae but few white dwarfs go supernova. The statement stated is actually false and a fallacy, not only leaving the reader not only confused but also deceiving them to believe something that is not true. If you believe your statement above is true, you have not comprehended what causes supernovae in the first place. Instead of arguing, let's now test this premise. Arianewiki1 (talk) 03:07, 29 June 2019 (UTC)


 * Is it possible to be non-specific? Remove mention of massive stars, white dwarfs, or anything else?  The only forms of words I can think of are impossibly wooly such as "... that last stages of life of some stars", but maybe there is something better that would keep the lead simple without being mis-leading.  I do share previous concerns about the word "destruction".  While collapsing into a black hole could be considered pretty destructive, it might be better to find a word that couldn't be taken by some as meaning that there is nothing left behind (beyond an expanding debris field).  Lastly, in the vein of "when in doubt, strike it out.", I'd like the drop the word "transient" in the lead.  It reads poorly and the phrase "transient astronomical event" sounds tautological to a layman.  Lithopsian (talk) 19:53, 28 June 2019 (UTC)
 * . I agree with most of the above.. I do have concerns that the remnant of supernovae can also be a neutron star/pulsar, and it is difficult to explain either total destruction against some remaining remnant in just of few words. Arianewiki1 (talk) 00:24, 29 June 2019 (UTC)
 * Something like: "A supernova is a titanic explosion marking the last stages in the life of a massive star or white dwarf". Attic Salt (talk) 20:03, 28 June 2019 (UTC)
 * Attic Salt saying "This really is ridiculous. The article discusses SN from both massive stars and white dwarfs. So, the definining first sentence can't mention one without mentioning the other." Yet another series of poor pointy edits for someone seemingly without any concept of necessary context. e.g. Saying: "A supernova is a titanic explosion…" shows why this is a problem with you. It is not just an explosion. Then bizarrely you then do this series of edits on core collapse here but don't comprehend its implications.
 * As for the white dwarf argument, it already appears in the 4th paragraph in the Introduction. What is really ridiculous is saying 'white dwarf' infers that all white dwarfs go supernovae. So do they?  Arianewiki1 (talk) 00:11, 29 June 2019 (UTC)

…I just looked up my computer dictionary, that says; "supernova a star that suddenly increases greatly in brightness because of a catastrophic explosion that ejects most of its mass." Surely, not all explosions are catastrophic? Arianewiki1 (talk) 04:31, 29 June 2019 (UTC)

RfC : Inclusion that White Dwarf Stars Go Supernova

 * The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

contends that : "A supernova is a transient astronomical event that occurs during the last stages of the life of a massive star or white dwarf, the destruction of which is marked by a titanic explosion."  They justify this addition by saying: "Since the article discusses SN from both massive stars and white dwarfs, the defining first sentence can't mention one without mentioning the other, otherwise the reader will be confused." Yet they still think: "No, it doesn’t say “all” white dwarfs, but rather “a” white dwarf."

As white dwarf stars above the limit (called the Chandrasekhar limit) of about 1.4 Solar masses will go supernova, but as given in initial statement (above) plainly infers that ALL white dwarfs go supernova.

There is also a contradiction, in that saying: "...that occurs during the last stages of the life of a massive star or white dwarf…", when a white dwarf is considered as ended its life as a star because it no longer creates energy by fusion while energy by a white dwarf is created by gravitational contraction.

This statement is therefore false and a fallacy.

Knowing that the number of these stars near 1.4 solar masses are rare, with the majority being less than this mass. Also these single white dwarf stars were likely once massive stars. Furthermore, the vast majority of massive stars, do go supernova.

Should "or white dwarf" in this statement be removed to fix this fallacy? 04:07, 29 June 2019 (UTC)


 * REMOVE. The statement as it is is plainly not true. The inference here makes the reader think that it applies to all white dwarfs. I.e. The Sun's eventual white dwarf will go supernova. (It won't.) If it is necessary to add this, then it must be better qualified to make the statement true. Due to the complexity of the nature of supernova and also making this statement true, "a massive star" is sufficient good to meet the general definition. Arianewiki1 (talk) 04:26, 29 June 2019 (UTC)
 * REWRITE. As noted, the article discusses how a supernova can come from either a massive star and or a white dwarf. The inclusion of "white dwarf" into the first sentence was made by Lithopsian: . I support its inclusion because I think that the defining first sentence can't mention one source of a supernova without mentioning the other, otherwise the reader will be confused. The sentence that concerns Arianewiki1 is written in the singular: "a supernova is" and "a massive star or white dwarf". Nothing in the sentence says that "all" white dwarfs result in supernovae. But the sentence certinaly needs work. I have suggested that the sentence might be written as: "A supernova is a titanic explosion marking the last stages in the life of a massive star or white dwarf", but we hardly had time to discuss this or other alternatives before this call for an RFC was made. And, yes, I'm open to discussing alternatives. And here are two alternatives, one of which might make Arianewiki1 happy: "A supernova is a titanic explosion of a massive star or white dwarf." or, less specifically, "A supernova is a titanic explosion of a star." And I'm not intending this last alternative to mean that "all" stars explode! Attic Salt (talk) 12:28, 29 June 2019 (UTC)
 * The opening statement of this RfC is neither neutral nor brief. Also, by jumping straight in with the name Attic Salt, it's tantamount to WP:RFC. -- Red rose64 &#x1f339; (talk) 15:03, 29 June 2019 (UTC)
 * Trout for for not paying attention to WP:RFCBRIEF.  (On a side note, I don't think mentioning another user's position goes against the section about using RfCs for behavioral problems, since there's no behavior mentioned, but it definitely contributes to the lack of neutrality in the statement).  I'd suggest you delete the RfC tag and try again.  –Deacon Vorbis (carbon • videos) 16:14, 29 June 2019 (UTC)
 * Please, no “binary system” stuff in the first phrase of the article. Aside of being an inappropriately placed boring specification, it doesn’t cover all scenarios possible with white dwarfs. A dwarf may be impacted by an unbound small star (in a dense cluster – why not), or two unbound dwarfs may collide by chance (less probable, but still possible), or a white dwarf may be ignited by impact of some object too small to qualify the system as binary, such as a Jupiter-mass planet. Incnis Mrsi (talk) 16:29, 29 June 2019 (UTC)
 * REWRITE. I think the lead section needs a pretty major overhaul and rewrite for a variety of reasons. On this particular point, I do think that it is important to make it clear in the lead section that there are two general classes of supernovae: core-collapse events whose progenitors are massive stars, and explosions of white dwarfs in binary systems. These points do not necessarily need to be in the first paragraph, but they should be in the lead section. It is important to include both classes of supernovae for a few reasons: (a) astronomers usually use the term "massive stars" to mean stars massive enough to undergo core collapse (see Stellar evolution), which is a different category from white dwarf progenitors, (b) white dwarfs are not "massive stars", (c) the progenitors of Type Ia supernovae aren't required to be "heavy" white dwarfs either, there are double-degenerate pathways where two white dwarfs in a binary can collide and trigger a SN Ia even if those white dwarfs are of typical/average mass before colliding. So it's not really necessary or generally correct to say in the lead that SN Ia come from "heavy" white dwarfs, although some of them do. One possible solution to all of this would be for the first paragraph to give a broader general definition that a supernova is a powerful and luminous stellar explosion, which generally brightens rapidly and then fades over weeks or months, and that at peak brightness the optical luminosity of a supernova can be comparable to that of an entire galaxy of stars. To explain the nomenclature, explain the difference between supernovae and novae in that supernovae are far more powerful events, and that a nova is an explosion of a small amount of material on the surface of a white dwarf star while a supernova is an explosion of a star itself. (The current lead section partly does this but doesn't explain that a nova is merely an explosion of material on the surface of a star while a supernova is what happens when a star itself explodes.)  Then, in a later paragraph in the lead, the different categories and progenitors of different types of supernovae can be explained briefly. In other words: my proposed solution is to remove from the first paragraph any discussion of what _kinds_ of stars explode: define a supernova as what happens when a star explodes, and then describe the progenitor and explosion types a bit farther down in the lead section where there's a bit more room to explain these points without trying to fit everything into a single all-encompassing sentence about what kinds of stars explode.  For the most part, this information is already there in the lead, but the text could be clarified and sharpened up a bit. (Maybe moving the paragraph about Milky Way supernovae to the bottom of the lead section would help to make the paragraph on progenitor types more prominent.) I would also suggest removing any references to stellar "life" from the lead: in my view this kind of anthropomorphising can cause confusion, even though astronomers do use this terminology loosely. For massive stars we can correctly say that core collapse occurs at the end of the star's evolution. For white dwarf explosions, it's probably best to avoid the "life" analogy altogether, to avoid confusion. Aldebarium (talk) 17:35, 29 June 2019 (UTC)
 * I've tried to follow up on this idea, following on from another edit. I made the first sentence much simpler, basically "its a big bright bang". Then the rest of the first paragraph tries to cover the various possibilities.  It may not be perfect yet, but I think the structure will let us be clear and complete without trying to cram a confusing mass of information in before we've even told the reader what a supernova is.  Lithopsian (talk) 14:21, 30 June 2019 (UTC)


 * REWRITE. In line with the other rewrite votes so far. In any case the text as it is presented here cannot stand. JonRichfield (talk) 04:55, 30 June 2019 (UTC)
 * Trim: Compare to the lead that was used for the FA promotion here, it has migrated quite a bit. Entropy happens, I suppose. I don't believe it now satisfies MOS:LEADLENGTH, so it needs to be trimmed down. Praemonitus (talk) 14:56, 12 July 2019 (UTC)
 * Chop away! I'm not sure the lead is too long for a very detailed and complex article, though.  I've looked at the lead to see what I might want to drop, and it isn't much, but then I've been too close to the article for a while and fresh eyes would help.  Lithopsian (talk) 15:03, 12 July 2019 (UTC)


 * The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Silicon Burning
How would silicon burning occur to produce 56Ni in Type Ia supernovae, if silicon burning occurs at a minimum of 8-11 solar masses, but white dwarfs reach critical mass at 1.4 solar masses? It's said in the second paragraph of the energy output section.

Strombolian (talk) 03:02, 19 September 2019 (UTC)


 * Where does it say silicon burning can only occur for a minimum star?  And more importantly, where does it say it can only occur in a supernova from an  star?  A very high proportion of the initial mass of the white dwarf (probably carbon and oxygen plus a few bits and pieces, possible neon, magnesium, a little accreted hydrogen) fuses all the way to "iron" (technically nickel which then decays radioactively), with the last stage being silicon burning.  There really isn't any other significant way to reach the iron peak elements.  Plus the references say so.  Lithopsian (talk) 13:18, 19 September 2019 (UTC)

Please fix number of visible supernova
Hi,

I added a citation needed on this page for the number of supernova observed in the Milky Way. The first citation needed is when it says only 3 supernova have been visible over the last thousand years. On other wiki pages like 'History of supernova observation' it mentions the following supernova have been observed, SN 1006, SN 1054, SN 1181, SN 1572 and SN 1604 which is 4 or 5 (depending on how strictly you want to adhere to thousand years).

The other citation needed is under the observation history where it says "Before the development of the telescope, only five supernovae were recorded." Again, from other sources there are certainly more than five recorded supernova as you have the five stated above along with SN 393 and SN 185 for at total of at least seven.

Can we get an expert to fix this issue and let us know how many visible supernova have been observed in the Milky Way? — Preceding unsigned comment added by 2001:569:77fd:400:1c39:1993:290a:6e4b (talk • contribs) 03:05, 22 December 2019 (UTC)
 * Removed. DrKay (talk) 17:08, 24 December 2019 (UTC)