Talk:UY Scuti

Distance, luminosity and parallax
I've created this article. I am just a 13 year old boy, and I just get my information from SIMBAD. Please help me add some information about UY Scuti's distance, luminosity, and parallax, if you have any information about it. Thank you! Johndric Valdez (talk) 12:07, 11 September 2013 (UTC) :)

Error in size determination
I've just turned to the list of largest known stars, and found out that UY Scuti has errors in its size determination. I fear that maybe my information might had just don't make it contrary to current ideas. You can edit my article if new results were found to its size. Johndric Valdez (talk) 12:07, 11 September 2013 (UTC)

Largest known star?
At an astonishing size of 2.38 billion kilometres, or 1,708 solar radii, UY Scuti has now taken the place NML Cygni held for more than a year. Some websites are now reporting UY Sct as largest known star, and it was true at all, based on observations.

But according to a smart, good friend under the name Lithopsian, about a dozen stars were fighting for the throne. And it was true, candidates were VV Cep A, PZ Cas, RW Cep, KY Cyg, Wd 1-26 and WOH G64. And Lithopsian has provided a journal on the List of largest known stars that states UY Scuti has erroric scheme of estimate. Based on this data, if we relied on this, more candidates will follow. The reason that I've put only "one of the largest known stars" is because of what Lithopsian said that nothing has really changed, lots of stars are still competing for the throne. So don't start up shouting UY Sct as largest, there are erroric possibilities in size estimates, with uncertain predictions. If you don't understand then just ask Lithopsian, because he's the expert.

To Lithopsian, please add a reliable journal concerning this. I need your help. ==Johndric Valdez (talk) 06:14, 10 October 2013 (UTC)==

UY Scuti is truly the king of stars, with candidates including PZ Cassiopeiae, VV Cephei A, VY Canis Majoris, KY Cygni, Westerlund 1-26, WOH G64, and NML Cygni. Nobody know who really is the largest star though, but it is best to say UY Scuti is the one. -- Joey P. - THE OFFICIAL (Visit/Talk/Contribs) 05:58, 28 October 2017 (UTC)


 * UY Scuti is smaller now. In the "UY Scuti" page, it says 909 solar radii now Hoanghao314159 (talk) 09:19, 19 May 2024 (UTC)

Mass correct?
The mass is given as 32 times solar mass. That seems impossibly low. — Preceding unsigned comment added by 94.226.172.196 (talk) 21:01, 15 December 2013 (UTC)
 * Why impossible? Red supergiants simply don't come much more massive than that.  The mass is of course only an estimate based on stellar models that most closely reproduce the observed characteristics, but the models have been verified against other methods such as binaries and they won't be hugely wrong.  Lithopsian (talk) 21:10, 15 December 2013 (UTC)

There is also a different mass written in the table detail : Mass	7–10[4] M☉ please unify the information, according to the arXiv paper linked it should be 25/30-40 M⊙ Cheers PapAngelos (talk) 14:54, 2 August 2018 (UTC)
 * Current mass and initial mass. Nothing wrong in the article, it even explains in the text.  Lithopsian (talk) 15:11, 2 August 2018 (UTC)

Supergiant or hypergiant?
UY Sct's spectral luminosity class and absolute magnitude fit it to become a hypergiant. Is this star a hypergiant or just a down-ranking supergiant? ==Johndric Valdez (talk) 12:06, 29 January 2014 (UTC)==
 * Hypergiant is not a term with a fixed definition. Specific to this case, red supergiants do not receive the O or Ia+ luminosity class because their spectra never show the relevant features, so hypergiant applied to an M star is simply a reflection of sufficiently high luminosity to place the star at the limits of stability, resulting in turbulence and high mass loss.  The stability limit for all cool stars is placed at around MV -9.5.  Lithopsian (talk) 12:35, 29 January 2014 (UTC)


 * In the first paragraph in the article of VV Cephei, it states there that "Although VV Cephei is an extremely large star showing high mass loss and having some emission lines, the spectral luminosity class and absolute magnitude do not qualify it as a hypergiant." VV Cephei A has the spectral type M2Iab, which is not for a hypergiant. Some other stars, like VY CMa and NML Cyg all have spectral class Ia, and UY Scuti has too. Also, it is stated that VV Cephei A does not have enough luminosity, being 200,000 times that of the Sun. So far I haven't seen any hypergiant star below 250,000 times the Sun's luminosity (like VY CMa and NML Cyg both having 270,000). But UY Scuti hs 340,000, so it may fall into the class of hypergiants. ==Johndric Valdez (talk) 14:18, 30 January 2014 (UTC)==


 * I refer you to the definition section of the hypergiant article. It says all there is to say really and I can't add to it (especially since I wrote it!).  Under that definition VV Cep fails completely to be a hypergiant.  You can argue about whether any red supergiant should be called a hypergiant or not, but the term has been commonly used by astronomers, some of whom are as keen on populist hyperbole as anyone else, and by the press release folks who are paid precisely to attract the attention of the public with fancy words like hypergiant whether they're appropriate or not.  On Wikipedia we should at least be internally consistent and any star classified here as a hypergiant should fit the definition given in that article.  If you feel the definition is wrong then feel free to change it, supported by suitable references of course. Lithopsian (talk) 15:14, 30 January 2014 (UTC)

Kick Up A Fuss, Big Error Deals
I am going to bring back what I've said above. Lithopsian was right. Almost all pages concerning the largest stars in the Internet only base their claims on here in Wikipedia. One edit here and hundreds (thousands?) will claim it. Too bad they only claim what they see here (like the table in the list of largest known stars page) and do not study those refs.

In just a matter of few months, I was surprised how many reports in the Internet claim UY Scuti defeated NML Cygni in the first place when the fact is UY Scuti is the more likely to be defeated. Simply this claim arouses because people only look at star rankings, not the references. So now, I would like to request, what about changing UY Scuti's size from 1,708 ± 192 solar radii to 1,515-1,900 solar radii (like on AH Sco. Lithopsian changed it from 1,411 ± 124 solar radii to 1,287-1,535 solar radii) simply because people claim what is unlikely to be the largest known star.

Look, NML Cygni's estimate is very precise, 1,650 solar radii, no more nor less. We can't figure it out on UY Scuti; we are not sure about the size, yet the Internet claims because it was in the highest, not understanding the refs. If we did the 1,516-1,900 figure, we will push him to 4th place, below VX Sgr, and will rethrone NML Cygni. We must do that because I don't want people to claim the largest star as a star with errors, rather a star with a sureball estimate. Johndric Valdez (talk) 14:22, 18 February 2014 (UTC)


 * I'm not comfortable claiming either of these stars is "the largest". Certainly not based on a single paper (each) using different methodologies and where the likely errors are much larger than the differences between the two stars.  But if someone wants to have a table of the largest stars then one star will have to be at the top and it will have to be the one with the largest reported radius, reported by us in as unbiased and consistent a way as possible, not using our own preferences to get one star or another to the top, however well intentioned that might be.


 * It isn't fair to say that NML Cygni has a radius of 1650, no more nor less. That is a number that doesn't even appear in the referenced paper.  I know because I am the one who typed it in to Wikipedia and I was uncomfortable when NML Cygni ended up at the top of the list, even more uncomfortable when it got featured on the Wikipedia home page because of it.  That number is merely implied by the temperature and luminosity given in the referenced paper, both of which have margins of error.  I simply didn't feel it was appropriate to quote a margin of error on the radius, just quoting a calculated radius was as far as I was prepared to push "own research".  Also, for UY Scuti it isn't fair to say that 1,708 ± 192 is the same as 1,515-1,900.  The margin of error quoted in scientific papers has a very specific meaning, and it doesn't mean that the figure is definitely somewhere between two numbers.  It could be larger or smaller, but with decreasing likelihood.  I quote a range of values where different papers quote different values.  I rarely include a margin of error simply because most people will misinterpret what it means.  For these two stars specifically, one radius measurement is based on the assumption of a circular disk of a uniform effective temperature leading to a given luminosity, assumptions which certainly aren't true.  While the other bases the radius on the observed sizes of the disk at certain wavelengths based on observations of water and carbon monoxide (combined with an assumed distance).  The two papers just aren't measuring the same thing.  The UY Scuti number is actually more rigorously derived, although still almost certainly too high.  In a range of measurements of objects all approximately the same size (as extreme red supergiants almost certainly are) with random observational errors, the star found to be largest is simply the one with the largest error.


 * All of which makes a table, and especially a single largest star, even more meaningless. Is 1500 bigger or smaller than 1400-2400?  Is 1500±500 bigger or smaller than 1400?  Maybe we should put KY Cygni to the top (or W1-26) since it has the largest quoted radius at 2850, but that number is almost certainly wrong, even the authors of the paper say so.  So I think we should only quote the numbers we get from the references, and then order the table in accordance.  Lithopsian (talk) 14:58, 18 February 2014 (UTC)
 * Maybe we should take it to those "list of (superlative) stars" articles - problem is laypeople love those sort of facts so we can try and make them as buffed as possible. Cas Liber (talk · contribs) 20:34, 18 February 2014 (UTC)
 * Please do not calculate a diameter and put it into Wikipedia; that is entirely your own research.At least I try (talk) 18:23, 6 May 2016 (UTC)

What does UY mean?
What does UY mean? — Preceding unsigned comment added by 82.139.81.0 (talk) 20:36, 12 March 2014 (UTC)
 * Variable stars are named with a captial letter starting with R and the constellation name, for example R Tauri. When there are more variables than letters, two capital letters are used, for example AB Cygni.  Lithopsian (talk) 20:48, 12 March 2014 (UTC)

Additionally, if the variable star is the 355th discovered in the constellation, it should be named with V and the number. Example: V766 Centauri, V567 Cygni, etc. Johndric Valdez (talk) 13:52, 21 March 2014 (UTC)


 * then UY Scuti would be "V355 Scuti" or something Hoanghao314159 (talk) 09:17, 19 May 2024 (UTC)
 * It's possible that variable stars have the most ridiculous naming convention of any class of astronomical objects (see Variable-star designation), and that's saying something. The names will never be simplified and regularized, because everyone interested in the stars would still have to know the old names in order to understand the literature, so renaming would just add to the cognitive baggage. PopePompus (talk) 12:18, 19 May 2024 (UTC)

Distribution Error
The article says that stars like these occur on average once per 1500 cubic light-years. This is obviously meant to mean something like one star per a volume equal to a cube 1500 light-years on a side (or perhaps a sphere of radius 1500 light-years), but it could also be misinterpreted as one star per 1500 ly^3, which would space them on average 11-12 light-years apart. 2620:72:0:52F:D50E:F71C:90F6:37E7 (talk) 17:12, 30 September 2014 (UTC)


 * Someone misinterpreted the Math. It is really a cube 1500 light years across and not "1500 cubic light years". SkyFlubbler (talk) 12:27, 10 October 2014 (UTC)

Someone fix this, I am not an expert, but 25 stellar radii is NOT 400 AU!!!
Scuti is surrounded by a thick ionized nebula extending out to 25 stellar radii (400 AU) and with four times the mass of the sun. The disc may be gases ejected by UY Scuti as it passed through the yellow evolutionary void a few thousand years ago. — Preceding unsigned comment added by 2601:D:2383:DAC:7473:D876:F7E1:7DE (talk) 09:56, 20 January 2015 (UTC)

UY Scuti's diameter (maximum):

2.644 billion km x 25 = $$66,12$$ billion km

$$66,120,000,000 / 149,800,000$$ (1 AU) $$= 442$$ AU (rounded)

Thus, 25 UY Scutian radii would be 442 AU. The diameter of the ionized nebula would be ~884 AU. -- Joey P. - THE OFFICIAL (Visit/Talk/Contribs) 04:55, 26 October 2017 (UTC)

Image
This image looks trollish. Could it be real? Hubblesite.org has no mention of observations of UY Scuti. --79.166.76.26 (talk) 07:46, 1 April 2015 (UTC)

I agree, this image is not a Hubble image as far as I can tell from google image search and searching on the Hubble site, could someone more advanced in editing than me examine and take it down if it's not an actual Hubble image of the star.73.254.181.101 (talk) 02:32, 7 January 2018 (UTC)

In what galaxy?
Can the article please identify the galaxy in which the star resides? Thanks! --Lbeaumont (talk) 02:44, 8 May 2015 (UTC)
 * It's just 9,500 light years away, so it's in the Milky Way. SkyFlubbler (talk) 16:08, 28 May 2015 (UTC)

On improving the article...
I'm passionate about improving this article to GA. I'd like and  to join me.. Would you? Thanks and regards— UY Scuti Talk  11:49, 15 January 2016 (UTC)
 * I would be delighted to. How can I help?—azuki (talk · contribs · email) 11:51, 15 January 2016 (UTC)


 * I highly disregard this. The only source that we can get for UY Scuti is by Torres 2012, and even that one is not complete. GA articles must have multiple references and massive consorted data, which is not yet available for UY Sct.


 * UY Scuti did not reached the fame enjoyed by VY CMa more or less nine years ago, making information about it relatively little. And in all honesty, the only thing that makes UY Scuti remarkable is its size. It was not discovered before 1850 nor a very special star to change the laws of stellar evolution. All that it has is that it is a large star and nothing else.


 * I tried to find any other reference in arXiv, but none has appeared. If you can improve it, do it and point out new thoughts, supported by references of course. SkyFlubbler (talk) 13:16, 15 January 2016 (UTC)
 * I'll go through today and make a formatting pass-through, and a copy edit of the article. There are some things that can be changed that will be good improvements, and give the article a huge boost. Let's get this article to GA status! :-)  ~Oshwah~  (talk) (contribs)   13:36, 15 January 2016 (UTC)
 * thanks for providing your insight on this.. And I agree sources are rare here.. We should've done the math before. (But I'll keep this on my watch and improve it whenever I could) Thanks and regards— UY Scuti Talk  18:17, 15 January 2016 (UTC)
 * I see no harm in tightening up the article. There aren't exactly hundreds of published papers on the star, but more than enough to demonstrate notability and back up an article.  No reason why it couldn't be made a good article, although perhaps not the largest good article there's ever been. I plugged in some basic data today and corrected a few minor points in the text.  Even the apparent magnitude was a couple of magnitudes out because it was a photographic instead of visual.  Lithopsian (talk) 20:48, 16 January 2016 (UTC)

External links modified
Hello fellow Wikipedians,

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 * Attempted to fix sourcing for http://solarsystem.nasa.gov/planets/profile.cfm?Object=Sun&Display=Facts&System=Metric

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Age?
Has the age of this star been determined? If so, what is it? If not, what factors prevent a proper determining of its age, and are there any potential scientific approaches being developed to determine its age? Inclusion of answers to these questions would constitute an improvement to this article. allixpeeke (talk) 12:28, 12 May 2017 (UTC)
 * UY Sct is around 5 million years old. You can quote me on that, although I'm not giving a margin of error ;) I'm not aware of any explicit publication of its age, although it is certainly "known" in the scientific community, subject to differences between models and determination of its physical properties. Arroyo-Torres includes an H-R diagram of evolutionary tracks, but does not mark the ages on the tracks. Picking a position on an evolutionary track is somewhat subjective, and likely was not considered reliable enough in this case to be published. The margins of error for the luminosity alone would suggest an initial mass anywhere from to, with a consequent large difference in the current age. Lithopsian (talk) 13:22, 12 May 2017 (UTC)
 * "Inclusion of answers to these questions would constitute an improvement to this article." allixpeeke (talk) 20:05, 15 June 2017 (UTC)

Hypergiant or not?
This article says UY Scuti is not classified as a hypergiant. The actual hypergiant article says it is. Which is it? 136.159.160.4 (talk) 18:54, 15 September 2017 (UTC)
 * Whichever you want :) Find good sources to support what you write.  Random fanboy web pages are not good sources.  Right now there is some commentary addressing the hypergiant question that is completely lacking inline citations, so almost anything you find would be better.  Then don't be offended if someone else changes it and uses a different source.  Just for the record, published scientific papers calling UY Sct a hypergiant are very thin on the ground, and the general thesis of the commentary is correct - ie. strictly there are no red hypergiants at all, just a few stars to which someone wanted to attach hyperbolae.  Lithopsian (talk) 20:28, 15 September 2017 (UTC)

Gaia distance
The Gaia DR2 catalogue gives for UY Scuti a parallax of 0.6433 ± 0.1059 mas, which translates to a distance of 1550 ± 260 pc, much less than the 2900 ± 317 pc assumed for the radius of 1,708 ± 192. The new distance, if correct, means the radius of the star is just 916. Should this be included in the article? Jolielegal (talk) 23:03, 10 June 2018 (UTC)
 * No. Doing so would be a violation of SYNTH. We can report the new value with a note regarding difference between the old radius and (calculated) new one. Primefac (talk) 01:17, 11 June 2018 (UTC)
 * Gaia DR2 parallax added. Torres et al. adopted distance maintained in the starbox and explained in the text.  No commentary added although it looks likely that the adopted distance (from the last century) is too large and derived properties such as the radius and luminosity are also too large.  Don't hold your breath for a peer-reviewed paper formalising this.  Lithopsian (talk) 10:43, 11 June 2018 (UTC)
 * That, as stated, would be a violation of WP:SYNTH. Do not get two values from two separate sources to get a conclusion not stated in any of the sources.  Joey717  (talk) 03:09, 9 September 2018 (UTC)
 * This is just a routine calculation. Ruslik_ Zero 20:42, 10 September 2018 (UTC)
 * If you want this to be done, please provide us with a reliable source/sources JayKayXD (talk) 13:15, 6 November 2018 (UTC)

Semi-protected edit request on 17 June 2018
180.191.150.91 (talk) 01:11, 17 June 2018 (UTC)
 * Red question icon with gradient background.svg Not done: it's not clear what changes you want to be made. Please mention the specific changes in a "change X to Y" format and provide a reliable source if appropriate. Primefac (talk) 01:57, 17 June 2018 (UTC)

A Commons file used on this page has been nominated for deletion
The following Wikimedia Commons file used on this page has been nominated for deletion: Participate in the deletion discussion at the. Community Tech bot (talk) 07:52, 28 June 2018 (UTC)
 * Comparison of planets and stars (2017 update).png


 * Actually, even though I created that file, I honestly think it isn't even accurate and at a good enough standard. Thus, I would actually support its deletion,  Joey717  (talk) 03:11, 9 September 2018 (UTC)

Mass of UY Scuti
When i checked the reference, the mass seems to be more like 20-40 and not 7-10. Maybe someone could have a look and fix if i read it correctly.--McBayne (talk) 21:59, 9 September 2018 (UTC)
 * Where did you see 20-40? Ruslik_ Zero 20:40, 10 September 2018 (UTC)
 * That would be the initial mass. Lithopsian (talk) 20:44, 10 September 2018 (UTC)
 * 20-40 are written in the conclusion and 7-10 are written as inputs for their model as far as i understand it.--McBayne (talk) 18:02, 11 September 2018 (UTC)
 * Read it again. Lithopsian (talk) 18:37, 11 September 2018 (UTC)

Sorry, my last citation about it. ''With the effective temperature and the luminosity calculated from the Rosseland radius, the bolometric flux, and the distance, we locate our targets in the HR diagram. The positions of the stars in the HR diagram fall close to the red limit of the tracks corresponding to stars of mass around 25/30–40 M⊙ (AH Sco and UY Sct) and 20/20–40 M⊙ (KW Sgr) with/without rotation.'' That sentence makes me think they ended up with these high masses but maybe you are right and this is really the initial mass.--McBayne (talk) 19:03, 14 September 2018 (UTC)
 * The critical word in that quotation is "tracks". Tracks are always based on initial mass.  Although not made blindingly obvious (preumably because it is blindingly obvious to a professional astronomer), this is consistent with other statements in the paper.  Lithopsian (talk) 20:25, 14 September 2018 (UTC)
 * Ok, thanks for the explanation.--McBayne (talk) 21:54, 14 September 2018 (UTC)

Time at the speed of light
We should change the paragraph about a hypothetical object moving at the speed of light taking 7 hours to taking an observed 7 hours. The disambiguation is importance because a luminal observer would claim that no time at all passed during the orbit. Northtreker (talk) 14:09, 11 November 2018 (UTC)


 * Sounds good. I changed it. CubeBag (talk) 21:37, 26 October 2019 (UTC)

Semi-protected edit request on 23 March 2019
Minor change to the second sentence of the article, language, probably a typo. change the following: "It also the largest known star by radius and is also a variable star" to: It is the largest known star by radius and is also a variable star, Kite4life (talk) 04:59, 23 March 2019 (UTC)
 * Yes check.svg Done Gulumeemee (talk) 06:35, 23 March 2019 (UTC)

Mass
How many times is it bigger than UY Scuti? — Preceding unsigned comment added by 2600:1700:3A20:25B0:8DC1:D0B1:82A3:889B (talk) 16:10, 28 August 2019 (UTC)


 * Exactly 1x. Lithopsian (talk) 16:24, 28 August 2019 (UTC)

Which star’s the largest? + Which radii are the most accurate?
Which star with what radius is the most likely star to be the largest? And what are the most accurate radii for uncertain stars like VV Cephei, Mu Cephei, Eta Carinae and IRC +10420 and stars of the basic sequence Sirius - Pollux - Arcturus - Aldebaran - Rigel - Deneb - Pistol Star - Antares - Betelgeuse? And is Antares bigger than Betelgeuse or not? And is Aldebaran bigger than Rigel or not? What’s the true diameter of UY Scuti since both estimates of its distance seem to be inaccurate? Nussun05 (talk) 17:26, 12 March 2020 (UTC)
 * It's hard to say which star is bigger. Look at Talk:List of largest stars to get an idea of the difficulty here. SevenSpheresCelestia (talk) 17:04, 14 March 2020 (UTC)

A Commons file used on this page or its Wikidata item has been nominated for speedy deletion
The following Wikimedia Commons file used on this page or its Wikidata item has been nominated for speedy deletion: You can see the reason for deletion at the file description page linked above. —Community Tech bot (talk) 04:53, 4 May 2020 (UTC)
 * UY Scuti zoomed in, Rutherford Observatory, 07 September 2014.jpeg

A Commons file used on this page or its Wikidata item has been nominated for deletion
The following Wikimedia Commons file used on this page or its Wikidata item has been nominated for deletion: Participate in the deletion discussion at the. —Community Tech bot (talk) 14:08, 4 May 2020 (UTC)
 * UY Scuti zoomed in, Rutherford Observatory, 07 September 2014.jpeg

Trustworthy source of UY Scuti size?
UY Scuti has for awhile been considered one of the largest known stars with a diameter of around 1700 times that of the sun. Yet suddenly I see that number changed to 755 times that of the sun based on one source. How reliable is that source? That seems like quite a big difference to attribute to an error in earlier models. I just don’t know if I trust the 755 solar radii number. — Preceding unsigned comment added by Jay72091(2) (talk • contribs) 02:05, 13 July 2020 (UTC) Jay72091(2) (talk) 02:07, 13 July 2020 (UTC)


 * Indeed, UY Scuti is no longer considered the largest star. The estimate given by Messineo and Brown is the most recent one we possess, so we are using the number it gives. Though GaiaDr2 indeed has room for inaccuracy, it’s not our job to catalog our the sizes we feel are ‘correct’. Wikipedia is not a platform for people who wish to share their opinions.PNSMurthy (talk) 02:57, 13 July 2020 (UTC)


 * Yes, that is a big difference, but also an indication of how unreliable all these estimates are. The previous large radius was derived assuming a particular distance.  Gaia has published a parallax that appears to be fairly reliable and gives a much smaller distance.  Hence a much smaller radius.  I'm not sure why you would put your trust in a radius derived from a distance which is from the last century and little better than a guess.  Things may still change again when Gaia's final release improves the accuracy of parallaxes further, hopefully including the tricky red supergiants, or perhaps when someone uses a different method such as interferometric maser parallaxes.  Lithopsian (talk) 14:42, 13 July 2020 (UTC)


 * Torres et all was from the last century? As far as I remember, only the 825 estimate was from the last century. I do think that UY Scuti's size will come somewhere in the middle of the estimates. A discrepancy of over 600 solar radii, at least in my eyes, is a little of an overshot.PNSMurthy (talk) 05:54, 14 July 2020 (UTC)
 * The distance used came from a different paper, published in the last century, with no further validation. The new size is the right size if the Gaia DR2 parallax is correct.  If not, then it will change again in some future paper.  The newer smaller value is more likely to be correct, or at least less inaccurate, than the older larger value.  You'll just have to get used to it.  Lithopsian (talk) 14:16, 14 July 2020 (UTC).


 * Don’t worry Lithopsian, I got used to it. In March, I happened to check on the list of largest stars... I found something... UY Scuti got downgraded !!!!! I was sad... But later on, I got used to It, and Accepted Stephenson 2-18 as the largest. Jay72091, you need to het used to it because this Beast is around 3 times  larger than UY Scuti and much, much ,much more voluminous!


 * UY Scuti is downright not the largest star anymore. Gaia parallax is one of the most, if not the most, sophisticated and accurate technique for measuring stellar parameters. Until the this catalogue is released, the estimate in the list if going to be UY Scuti's official estimate.PNSMurthy (talk) 00:28, 23 July 2020 (UTC).
 * Yep. I got used calling UY Scuti only as a 755 solar radii star. Huge, But not as large as before when we thought it was the largest star. It seems that Stephenson 2-18 was lurking behind everyone’s attention because the 2,150 or 2,163 solar radii estimate comes from a reference in 2012. this likely means that Stephenson 2-18 was the largest since 2012 or 2014 because NML Cygni was the largest back then and after that Westerlund 1-26. UY Scuti was the largest since Westerlund 1-26, but since UY Scuti has a smaller size estimate than Stephenson 2-18 It should be that Stephenson 2-18 is the largest. It might have been that it was the largest for 6 or 8 years.--THE COLOSSAL GALAXY NAMED IC1101 (talk) 07:46, 23 July 2020 (UTC)


 * What's past is passed. Forget about all that, it's not like there's some championship for the largest known star...PNSMurthy (talk) 05:41, 24 July 2020 (UTC)

The Truth of UY Scuti's Mass
There are some controversial about UY Scuti's mass. Because UY Scuti looses mass, tons of them every year or so. 7:35,25th September 2020 (UTC) — Preceding unsigned comment added by Daniel kun 22 (talk • contribs)
 * UY Sct is losing per year, which is only  Nussun05 (talk) 14:51, 30 September 2020 (UTC)

Distance and Properties
Well, I saw UY Scuti's details got reverted back to its old 2013 details based on the old 2.9 kpc again since its 1.55 kpc Gaia DR2 distance appears to be as possibly not accurate. But I think we should keep the Messineo properties and the Gaia DR2 distance since the 2.9 kpc distance is now considered highly old (made in 1970) and obsolete (and now should unlikely to be used). You can't just go back in history, especially if the estimated distance is 30 years older than the new one since observations and methods since prior to 1990-2000 are much less reliable than current ones. And also UY Scuti is also considered as an intermediate-size luminous supergiant (Ia-Iab), thus its actual luminosity would be likely smaller than the from Torres 2013. However, I can't find distances for UY Scuti other than the 1970 and Gaia DR2 distance though authors may gives the star an actual distance (maybe larger than the Gaia DR2 but likely smaller than the 1970 distance) in the future. 2A01:E0A:47A:F100:5DDF:BD27:7374:95E6 (talk) 00:25, 3 October 2020 (UTC)
 * Difficult indeed. The Gaia DR2 parallax is undoubtedly unreliable, but then so is a guesstimate distance from last century.  Gaia EDR3 is expected in two months time.  Although it won't have a dramatic overall improvement in the accuracy of parallaxes, it should reduce systematic errors and perhaps give some pointers.  Meanwhile this recent paper considers UY Sct an extreme red supergiant on observational criteria independent of its distance and compares it to S Per. Lithopsian (talk) 10:45, 4 October 2020 (UTC)
 * Maybe we can at least re-add the in the starbox by saying that UY Sct is between seomwhat 755 and 1,708 and  (just like V354 Cephei when when you re-added the  value), and as well as 3,605 K since the 3,605 K temperature is based on its respective spectral type of M3 with the most reasonable temperature scale proposed by Emily Levesque. 2A01:E0A:47A:F100:2921:B177:5326:C7C (talk) 10:53, 4 October 2020 (UTC)

Radius Arguments
I have been in discussion with an individual who argues:

"The time past since publication is not a scientific criterion to evaluate papers (in fact, it is a kind of "argumentum ad novitatem"). Of course, new publications rely on new measurements done with more precise instrumentation, but "better precision" means not "better results". The best example of this is the problem with the distances for large stars provided by Gaia.

About the two papers you mentioned: - Cruzalébes et al. 2019: They do not give a angular (or physical) diameter for UY Sct. They only provide the distance for UY Sct and iot is not original, but taken from Bailer-Jones et al. (2018). As the distances from that work are calculated from Gaia, they have the same problem mentioned above. Thus, any radius calculated from that distance for Uy Sct can not be really trusted. - Van Loon et al. 2005: The data for red supergiants used in this paper is probably enough for their scientific objetive (to study the mass-loss in a statistical way). However, such values are not very reliable for specific objects, and in the specific case of UY, the data is especially problematic. Firstly, the luminosity of UY Sct was not calculated by them, but taken from Jura & Kleinmann (1990). In that paper, this is said about this star: "We include two stars in Table 1 whose distances are not well established but which have sufficiently long periods that they may be massive stars: KW Sgr (F = 670 days) and UY Set (F = 740 days). Neither of these stars is a Mira, and spectroscopically they are classified as supergiants. We assume nominal distances to these stars of 2 kpc, but this is uncertain." If this is not bad enough, the other ingredient for the calculation of the radius, the temperature, is also problematic. From Van Loon et al. 2005: "The stellar effective temperatures corresponding to the M-type spectral subclasses are taken from Fluks et al. (1994). These are strictly speaking valid for luminosity class III giants of solar abundances, and differences may be expected for metal-poor stars and for luminous supergiants. (...) The thus adopted values are probably only accurate to ∼300 K (cf. Houdashelt et al. 2000)." Therefore, their temperature is not a precise measurement, but an estimation using a scale created for red giants. In conclusion, the two ingredients used to calculate the radius of UY Sct are not reliable at all. This does not mean that the distance from which the previous size was calculated (taken from Lee 1970) is absolutely correct. But there is not necessity of believing this paper. Is at simple as this: UY Sct is a M4 Ia star. Its radius can not be smaller or about the size of "typical" red supergiants, as Betelgeuse which is a M2 Iab. It has to be larger... roughly similar to the radius calculated for other M4 Ia stars as VY CMa (1400 Rsun) or BI Cyg (1200 Rsun), which is almost twice the radius derived from Gaia."

Any assessments on this comment? I would appreciate opinions. Faren29 (talk) 17:04, 7 October 2020 (UTC)


 * Some POV problems, of course: "all these papers are inaccurate, except the one that gives the answer I like". The argument in the last paragraph is pure fantasy.  Looked at with less bias, they are all inaccurate.  We just have to choose which one (or possibly more than one) is least flawed and most reflective of scientific consensus.  That is often the most recent, not always.  Studies dedicated to the star rather than blind algorithmic calculations are to be preferred all other things being equal.  The Gaia parallax is unreliable, but so is the 1970 distance estimate.  It is likely the actual distance is somewhere between the two, but we have no good way of knowing just where.  Gaia DR3 is released in a little over a month; it may well have the same problems as Gaia DR2, but could improve on things a little.  This recent paper, independently of any distance, considers UY Sct to be a "veiled" "extreme" red supergiant and compares it to S Per.  Lithopsian (talk) 13:36, 13 October 2020 (UTC)


 * In any case the angular diameter in the MDFC catalog doesn't significantly change the diameter value from the previous value (5.5 vs 5.8 mas). It could be possible to calculate the diameter using old distance and new diameter, but this may be considered WP:SYNTHESIS. Ardenau4 (talk) 05:39, 16 October 2020 (UTC)

How do you pronounce it??
Alshfik (talk) 14:49, 14 December 2020 (UTC)


 * SCYOOT-eye (British English) or SCOOT-eye (American English). Faren29 (talk) 16:34, 16 December 2020 (UTC)
 * I always pronounce it “UY SCOOT-E” Atlantlc27Lol (talk) 01:19, 25 December 2023 (UTC)

Position on the list
Should the star be in the list at all? On one side we have a radius based on an old, obsolete and borderline guesstimate distance from 1970, and on the other side we have two radii based on Gaia data, which has a level of astrometric noise far above acceptable. Do we pick obsolete data or unreliable data? I say neither. Faren29 (talk) 02:11, 1 January 2021 (UTC)
 * Both? The real value is probably somewhere between the two.  Lithopsian (talk) 14:45, 1 January 2021 (UTC)
 * I'm planning to work as an astronomer in the future, maybe in around ten years I will measure the radius myself and report back. ;)


 * Maybe it is, but the current radii we have for the star right now are all inaccurate for the reasons stated above. We strive to have the most accurate radii possible on the list, or at least radii that isn't fundamentally in dispute. Faren29 (talk) 16:40, 2 January 2021 (UTC)
 * See WP:TRUTH. There is some scope for commentary in the text about data which is likely to be highly inaccurate, always bearing in mine WP:OR and WP:SYNTHESIS and remembering that the radius of every red supergiant is pretty inaccurate.  The most obvious cases for discussion in the text are when we have contradictory values.  Lithopsian (talk) 16:25, 3 January 2021 (UTC)

Magnitud Absoluta Incorrecta?
Hola, estaba buscando acerca de la magnitud absoluta de la estrella UY scuti, y vi que en este articulo era -6.2 entonces la posicione en el diagrama de H-R pero no cuadraba con su luminosidad ya que es de 340.000 L☉. Calcule la magnitud absoluta y era de -7.983,8

Si mis cálculos están mal háganmelo saber, pero de lo contrario sugiero que corrijan el articulo :) APHE1 (talk) 20:41, 4 January 2021 (UTC)
 * See absolute magnitude, bolometric magnitude, and bolometric correction. Lithopsian (talk) 21:02, 4 January 2021 (UTC)
 * Me guie por este articulo Magnitud Absoluta, y aplique la primera operación, esta mal? APHE1 (talk) 15:51, 6 January 2021 (UTC)
 * See also Magnitud bolométrica. Lithopsian (talk) 17:05, 6 January 2021 (UTC)

Semi-protected edit request on 10 February 2021
must be: "estimated radius of 1,708 solar radii" ==> "estimated radius of 1,708 solar radius" ok? 78.190.254.238 (talk) 12:38, 10 February 2021 (UTC)


 * Red information icon with gradient background.svg Not done: It looks correct to me as is, "radii" is the plural of "radius". In the same way you'd write the plural for 10 seconds and 20 metres, you write 1,708 solar radii. Volteer1 (talk) 13:24, 10 February 2021 (UTC)

RHG? (Again)
Now, recently, I've been viewing Tabernero et al (],the study which says that VX Sagittarii is an AGB star) and on page 2, it states that both S Persei and UY Scuti are Red hypergiants. The specific text is:
 * "Whereas typical RSGs show changes no larger than 2 mag (Kiss et al. 2006). Even extreme RHGs (e.g. S Per, UY Sct, and VY CMa; Schuster et al. 2006) show a maximum peak-to-peak variation of only 4 mag, according to AAVSO photometric data. In the I-band, RSGs present variation amplitudes smaller than 0.45 mag, while AGB stars have larger amplitudes (Groenewegen et al. 2009). In contrast, VX Sgr has a peak-to-peak variation of 1.2 mag (Lockwood & Wing 1982) in that photometric band. We also note that the spectral variation of VX Sgr is unique among RSGs since it spans around 6 spectral subtypes (from M4 to M10; Humphreys 1974; Lockwood & Wing 1982). Most Galactic RSG have variations of one subtype or less (White & Wing 1978), whereas the RHGs change by no more than 2-3 subtypes."

On top of that, up on the page another paper (]) describes UY Scuti as an extreme red supergiant (E-RSG) and it was compared to S Persei. What are your thoughts? Let me know down below, so we can add it or not add it. Bye !--The Space Enthusiast (talk) 10:16, 24 April 2022 (UTC)
 * If you've got reliable sources ... Lithopsian (talk) 13:12, 24 April 2022 (UTC)

Add more context to relative size and impact
In the description it says

If placed at the center of the Solar System, its photosphere would at least engulf the orbit of Jupiter.

Could be improved by saying something like,

If placed at the center of the Solar System, its photosphere would at least engulf the orbit of Jupiter, while the nebula of gas ejected from the star would extend far beyond the orbit of Pluto.

Sources located here. Ispottedsomething (talk) 14:59, 27 February 2023 (UTC)


 * No, because it did not provide a source of where that circumstellar nebula size came from. You need a scientific journal or peer-reviewed paper for that, not just some random Internet website. SkyFlubbler (talk) 05:43, 11 April 2023 (UTC)

Estimated radius
I’ve been told that the radius of UY Scuti was not based off of measurements by the GAIA EDR3 spacecraft.

Therefore I edited the page stating the star’s radius has been given various estimates, including an old estimate of 1708 +/- 192 Rsol, and a more recent estimate of 755 Rsol from GAIA DR2.

We know neither of these estimates are reliable, and I found no source stating its estimate was 825 Rsol. Eric Nelson27 (talk) 13:09, 24 November 2023 (UTC)


 * No source explicitly stated that it is, however, Van Loon et al. (2005) derives a luminosity and effective temperature resulting in that radius. I would not consider it accurate though and the log(L) seems to be very specific (5.00) and other stars in the same table have that luminosity.  SpaceImplorer ExplorerImplorer   13:23, 24 November 2023 (UTC)
 * Still, the page has to be based off of reliable sources, therefore I fixed the page to have information based off of such sources. Eric Nelson27 (talk) 13:46, 24 November 2023 (UTC)

Volume math fail
"... 755 solar radii (525,000,000 kilometres; 3.51 astronomical units), thus a volume over 2 billion times that of the Sun ..."

If the star's radius is 755 times the radius of the sun, then its volume is 'only' 430 million (755^3) times bigger, not 2 billion. 2600:1002:B17F:E76:791B:4042:8C13:6D70 (talk) 10:11, 11 January 2024 (UTC)

"possible considered" does not mean the same as "considered possibly"
The sentence ought to read "It is considered possibly one of the largest known stars."

Or even better (if you want to be super grammatically correct): "It is considered to be possibly one of the largest known stars."

105.161.198.160 (talk) 09:50, 17 February 2024 (UTC)BurnLootMurd...


 * Ok, I replaced the excerpt in the lead section of the article. InTheAstronomy32 (talk) 15:18, 17 February 2024 (UTC)