Talk:Main sequence

Dwarf?
Could someone explain the reason why stars on this sequence are called "dwarf stars"? The article doesn't explain the origin of the term at all. --LostLeviathan 05:01, 20 March 2006 (UTC)

These stars are hot, dim, and tiny compared to the Sun. They are actually remnants of stars. They are called dwarfs simply because they are very small. There is no real "origin" of the term.


 * I disagree with the above (unsigned) argument. I think LostLeviathan was asking about Main Sequence stars being described as dwarfs, and not about White Dwarfs which are hot, dim, tiny, stellar remnants but are not on the main sequence.


 * Stars appear to be described as "dwarf" or "giant" with no "normal" size between the two. I think the most likely explanation (and feel free to correct me on this point if you think I'm wrong here), is that at the time the phrase was first coined around 1910, these were the smallest, dimmest stars of their colour that had been observed.  Since then we have discovered white dwarfs, metal-poor sub-dwarfs and other types of small, dim stars.
 * Astronaut 16:54, 28 July 2006 (UTC)


 * I was going to ask the same thing. Why are main sequence stars also called dwarf stars? This definately needs to be explained in the article. Especially since the table at the end of the article seems to describe stars in their main sequence, yet includes a star or 16 solar radii and over 100 solar masses! I am generally quite knowledgable about astronomical topics, but if this has me confused it's safe to say the vast majority of readers will be as well.


 * So someone in the know: why are main sequence stars also called dwarf stars, and just how big a range does this classification have? ie, how big can a star be while still being called a dwarf? Harley peters 19:45, 8 October 2006 (UTC)


 * I added an explanation. Also how big a star can be and still be called a dwarf depends on the temperature. Roadrunner (talk) 05:24, 31 March 2009 (UTC)

Actually now that I reread the paragraph, it is totally wrong. Type-M Red dwarfs are main sequence stars but so are Type-O blue supergiants. Roadrunner (talk) 05:33, 31 March 2009 (UTC)

Even if there was some historical/jargon reason to call all main sequence stars "dwarfs", for a general audience it seems ridiculously misleading to call them that. To people who have a little bit of astronomy knowledge, "dwarf" calls to mind the white, black, brown, and red dwarf stars, and to people who have no astronomy knowledge it brings to mind the word "small". Show any layperson the size comparison picture of Rigel B versus the Sun and tell them it's a dwarf, and see what they say. "Main sequence star" is less ambiguous without being any less precise. --142.25.102.130 (talk) 00:47, 16 March 2012 (UTC)


 * Sure, let's ignore facts and just make stuff up to suit people's lack of knowledge (sarcasm alert!). If it isn't obvious that dwarf in this context refers to both small and large stars then explain it. Lithopsian (talk) 22:04, 14 November 2012 (UTC)

Discrepancy between Mass and Star Class
The chart here does not have the same values as the chart here. Both are part of Wikipedia. Can somebody fix this? JW Bjerk (talk) 02:50, 15 February 2011 (UTC)
 * One of the charts gives ranges across each of the major classes; the other gives discrete values for specific spectral classes. Thus they are not incompatible and do not need to be fixed, at least as far as I can tell. Thanks.&mdash;RJH (talk) 15:35, 15 February 2011 (UTC)
 * It would be best to update all the tables of mass, class, and temperature to reflect the most recent classification: http://www.pas.rochester.edu/~emamajek/EEM_dwarf_UBVIJHK_colors_Teff.txt . THere have been major changes in spectral classifications, especially in M and OB stars. 2601:441:4180:2440:3D40:64B1:E56A:1F9 (talk) 19:27, 9 February 2017 (UTC)

Simple english
I'm not sure if anybody watching this has an account on the Simple English Wikipedia, but the description there seems a little messed up. In particular, the CNO cycle occurs with higher mass stars, rather than lower mass stars. There are a few other minor inconsistencies as well. Thank you. Regards, RJH (talk) 20:01, 23 March 2012 (UTC)

There are a few contradictions in the opening section. Convection as well, first it says that large stars have convection, with smaller having less convection. Then it says smaller are increasing convection. I don't know enough about this to tell which is wrong, but these closing paragraphs aren't right. Saw a similar contradiction on another star section about white dwarfs. Might want to check if someone has been swapping sentences for their opposite. — Preceding unsigned comment added by 70.162.231.254 (talk) 17:39, 16 August 2021 (UTC)
 * Read it again, more carefully this time. And then think about not piling into 9-year-old comments that aren't even about this article.  Lithopsian (talk) 09:55, 17 August 2021 (UTC)

Some context for the layman
What other types of stars are there other than main-sequence? What type is our sun? I think these points should be address in the introductory part of the article. 188.169.229.30 (talk) 17:09, 7 June 2012 (UTC)
 * I added a sentence for the first paragraph. Hopefully it helps. 2601:441:4180:2440:3D40:64B1:E56A:1F9 (talk) 23:30, 9 February 2017 (UTC)

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Describing white dwarfs
Referring to white dwarfs, the article states: "These represent the final evolutionary stage of many main-sequence stars." It would more clearly represent the source if it stated: "These are an evolutionary stage many stars reach long after leaving the main-sequence." - Fartherred (talk) 16:36, 29 June 2016 (UTC)
 * [DoctorJoeE], you should not have reverted my comment on this talk page. If you disagree, state your disagreement.  Fartherred (talk) 18:49, 29 June 2016 (UTC)
 * DoctorJoeE disclaims reverting my talk page entry earlier, even though his name appears in the history of this page as reverting. Perhaps his account or a Wikipedia server was hacked.  - Fartherred (talk) 21:42, 29 June 2016 (UTC)
 * There is some lack of perfection in the article, but I have given up on trying to make an actual improvement. Considering the level of my expertise, it is too difficult.  - Fartherred (talk) 23:17, 26 July 2016 (UTC)

Lifetime
The equation for main-sequence lifespan does not give results that match the numbers I'm seeing in other sources, such as http://www.atnf.csiro.au/outreach/education/senior/astrophysics/stellarevolution_mainsequence.html. Does that equation only apply to a specific range of stellar masses, or are the above website and/or the book that supplied that equation out of date? Or am I just not understanding the math? I can say that the equation does not match the results of this study for stars <0.25 solar masses: http://iopscience.iop.org/article/10.1086/304125/pdf;jsessionid=EA018F69CE41C137D0722C4B2B961C88.c3.iopscience.cld.iop.org 2601:441:4180:2440:3D40:64B1:E56A:1F9 (talk) 19:21, 9 February 2017 (UTC)

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Why are blue main-sequence stars never called blue dwarfs?
Seriously, I've known one of the stars in the Beta Centauri system to be a "blue dwarf" - when I mean "dwarf", I mean main sequence star.

But why are O and B (early)-type main sequence stars never referred to as "blue dwarfs"? They are not as luminous as even their giant and supergiant counterparts, and not all of the "blue dwarfs" expected to form when red dwarfs exhaust their hydrogen supply are expected to be blue, but rather have temperatures just as hot as the Sun (just like the blue loop). The subdwarf O stars and subdwarf B stars are already almost as large as the Sun, but not even as luminous.

105.98.210.26 (talk) 23:42, 15 July 2019 (UTC)


 * The simple answer is that they are called blue dwarfs sometimes. Look, blue dwarf even says so.  However, it is not that common and I prefer to avoid it, partly because there are other things called blue dwarfs and partly because a blue dwarf can be a very massive and luminous star by comparison with just about everything else.  I think the term was more popular in the past, but a search of recent academic publications shows almost every reference to "blue dwarf" being to galaxies.  Lithopsian (talk) 16:43, 16 July 2019 (UTC)

The discovery of fusion as the source of stellar energy
I was looking for the history of the idea that nuclear fusion was the source of stellar energy. As I understand it, Payne-Gaposchkin first showed that stars are mainly hydrogen and helium. But I don't know who and when suggested that hydrogen fusion would account for stellar energy. Before P-G, stellar energy was a mystery. But I cannot find any discussion in Wikipedia for this major discovery, building on P-G's surprising result about hydrogen. How did someone come to realize hydrogen fusion. And, btw, it would be interesting to hear the prior history, how chemistry - burning - was discounted as a source, and how gravitational collapse was suggested. Is there any where in Wikipedia where this history is discussed? TomS TDotO (talk) 23:48, 8 February 2021 (UTC)
 * See the article on Hans Bethe for a summary. It could be useful to add a few sentences or a very brief paragraph to the History section of the Main Sequence article to describe Bethe's role in solving this problem, although this article is not the place for a very detailed account. Aldebarium (talk) 01:54, 9 February 2021 (UTC)

Thank you. Perhaps this article is not the best place to discuss the history of "what makes the sun and stars shine". But somewhere there should be an article where it pointed out that somebody first said. "Hydrogen fusion is producing energy." I didn't get the impression that it was Bethe, from his article. Perhaps George Gamow? TomS TDotO (talk) 05:47, 9 February 2021 (UTC)
 * See Stellar nucleosynthesis and specifically the history section. The basics of what you were looking for seem to be there.  Perhaps it could be linked more clearly from other articles such as this one, star, and stellar evolution.  Lithopsian (talk) 16:17, 9 February 2021 (UTC)
 * Thank you. That article gives the sort of information that I was looking for. It seems to say that the idea of hydrogen fusion was first suggested by Eddington in 1920. I am confused, however, by the article on Payne-Gasposckin, which says that her proposal in 1925 that stars are mostly hydrogen and helium was considered unacceptable. I don't claim to know anything, so I can't offer anything positive. I'll just have to let it pass. TomS TDotO (talk) 18:21, 9 February 2021 (UTC)
 * Eddington's idea was really quite vague, just a suggestion that fusion of hydrogen was a sufficient power source for stars. We pick it out now because it happened to be right, but lots of people at the time were casting about for solutions to the problem that gravitational contraction just wasn't sufficient to power stars. Similarly, Payne-Gaposchkin's thesis happened to be right, but it certainly wasn't accepted immediately.  It did catch on following essentially the same results published by another astronomer in 1929, then the exact CNO cycle was determined in 1938, followed by the B2FH paper in 1957.  Sometimes little soundbites get taken out of the whole sequence without the full context.  No doubt many of these articles could be improved, but history isn't really my strong suit.  Lithopsian (talk) 18:49, 9 February 2021 (UTC)


 * Thanks. That makes sense. There was a lot going on in the 1920s. So much that we take for granted today as basic astronomy - what kids learn in grade school. TomS TDotO (talk) 21:21, 9 February 2021 (UTC)

RfC 24 July 2021: Inconsistent hyphenation
In this article (Main sequence), Stellar evolution, Pre-main-sequence star, and O-type main-sequence star, "main sequence" is inconsistently hyphenated; more instances than just these likely exist. Category:Main-sequence stars, Category:Pre-main-sequence stars, and Category:O-type main-sequence stars are hyphenated. Should "main sequence" be consistently&#160;hyphenated, or consistently&#160;un&#8209;hyphenated? &#8212;&#160;CJDOS,&#160;Sheridan,&#160;OR&#160;(talk) 17:12, 24 July 2021 (UTC) — Relisted. &#8212;&#160;CJDOS,&#160;Sheridan,&#160;OR&#160;(talk) 10:14, 16 August 2021 (UTC)
 * Perhaps you misunderstand the purpose of hyphenation. It is there to disambiguate phrases that could otherwise be parsed in two different ways. "Main sequence", as a standalone noun phrase, is unambiguous and should not be hyphenated. "Main sequence star" could be parsed as a "sequence star" that is somehow "main" among the class of "sequence stars" (a nonsensical concept, but grammatical) or as a "star" that is part of the "main sequence" (the correct parse). To disambiguate this, it should be hyphenated: "main-sequence star". The standalone "main sequence" and the compound "main-sequence star" should be hyphenated differently; it is incorrect to ask for both to be hyphenated the same way. —David Eppstein (talk) 19:30, 24 July 2021 (UTC)
 * To clarify, are you suggesting that the standalone "main sequence" should be hyphenated, but not as "main-sequence"? Do you mean, use an en dash instead, e.g. "Post–World War II economic expansion" when used as a time specification (after World War II, not Post-World of War II)? &#8212;&#160;CJDOS,&#160;Sheridan,&#160;OR&#160;(talk) 19:49, 24 July 2021 (UTC)
 * I mean that, when it occurs by itself, "main sequence" should not be hyphenated at all. It should be written as "main sequence". When it occurs as part of the larger phrase "main-sequence star" it should be hyphenated as "main-sequence star". —David Eppstein (talk) 19:58, 24 July 2021 (UTC)
 * This paragraph might be of use to you:
 * Temporary adjectival compounds may also be formed by using a compound noun. If the compound noun is an open compound, it is usually hyphenated so that the relationship of the words to form an adjective is immediately apparent to the reader ("a tax-law case," "a minor-league pitcher," "problem-solving abilities"). If readily recognizable, the units may occur without a hyphen ("a high school diploma" or "a high-school diploma"; "an income tax refund" or "an income-tax refund"). Also, if the words that make up a compound adjective follow the noun they modify, they fall in normal word order and are, therefore, no longer considered unit modifiers that require hyphenation ("The decisions were made on the spur of the moment"; "They were ill prepared for the journey"; "The comments were made off the record"; "I prefer the paint that is blue gray"). Source:
 * (On the other hand, these "compounds" used as a noun may be hyphenated, written separately or as one word; "main sequence" is two words in this particular case).
 * Tl;dr: The current system is correct; the change would make it grammatically wrong. Szmenderowiecki (talk) 07:07, 18 August 2021 (UTC)
 * Not so much grammatically wrong as semantically wrong; in this connection the hyphenation affects the intended meaning of the usage. Each example is potentially grammatically correct in the sense that say, "main-sequence" and "main sequence" do not violate any grammatic rules intrinsically. The preferable choice of terms depends on the writer's intention. I have not offhand noticed any examples that need correction in the current version of the article. JonRichfield (talk) 07:28, 8 September 2021 (UTC)
 * I'm comfortable with the non-hyphenated usage, perhaps because I'm familiar with the terminology and so the lack of a hyphen is in no way confusing for me, but there is a considerable history of editors combing Wikipedia to fix this sort of grammatical "mistake". Even to the extent of renaming articles (eg. see red giant branch).  Consistency within one article would be good, though.  Lithopsian (talk) 19:51, 18 August 2021 (UTC)
 * It was in the evening and I was tired, so I did not immediately grasp what was saying in his reply, but reading it the next day, I agree with it. We also have Pre-main-sequence star which hyphenates   while other articles use an en dash to specify how it is joined with the following word or words (see Wikipedia talk:Manual of Style/Archive 221).  has made a useful point. I also concur with ; while trying to read the article, I kept reading over hyphenated and un-hyphenated versions of the same compound, and found it distracting. Whichever way is correct would be the way to go, I just want it to appear consistently. &#8212;&#160;CJDOS,&#160;Sheridan,&#160;OR&#160;(talk) 21:08, 18 August 2021 (UTC)
 * Comment Only here for the RFC. Most of the comments are either sound or open to specific correction or debate, but specifically I agree with practically in detail. In  English, separation, hyphenation, and agglutination are to some extent arguable and subject to convention, but they generally affect the expression that the writer intended, of the logical relationship between the components of terms, and between the terms and neighbouring words; they consequently also affect the ease of comprehension of the reader -- ill-considered expression tends to generate garden-path sentences or outright ambiguity. Sometimes arbitrary usage hardly matters, but hyphenation or separation or agglutination often completely changes the meaning of the expression, or affects the clarity or the emphasis; cf. "common sense" vs. "common-sense" vs. "commonsense". So the effect of hyphenation generally justifies some care and sensitivity in one's choice of appropriate notation. JonRichfield (talk) 07:28, 8 September 2021 (UTC)
 * Comment Only here for the RFC. Most of the comments are either sound or open to specific correction or debate, but specifically I agree with practically in detail. In  English, separation, hyphenation, and agglutination are to some extent arguable and subject to convention, but they generally affect the expression that the writer intended, of the logical relationship between the components of terms, and between the terms and neighbouring words; they consequently also affect the ease of comprehension of the reader -- ill-considered expression tends to generate garden-path sentences or outright ambiguity. Sometimes arbitrary usage hardly matters, but hyphenation or separation or agglutination often completely changes the meaning of the expression, or affects the clarity or the emphasis; cf. "common sense" vs. "common-sense" vs. "commonsense". So the effect of hyphenation generally justifies some care and sensitivity in one's choice of appropriate notation. JonRichfield (talk) 07:28, 8 September 2021 (UTC)


 * Conclusion: Some trouble with Legobot, which was clarified on my talk page. I think I've received all the responses I need (or will get). I'll leave this open until 16 September (8 days), after which I'll close this discussion. If someone wants to keep this open longer, then I'll leave it with them. &#8212;&#160;CJDOS,&#160;Sheridan,&#160;OR&#160;(talk) 18:00, 8 September 2021 (UTC)

Contradiction?
the article says a star remains at the same position on the sequence until hydrogen is depleted, but doesn't clearly say wherher it then moves off the MS, or up the MS. It also says that it gradually increases in temperature and brightness, implying it moves up not off the sequence. 47.17.56.98 (talk) 20:11, 24 November 2023 (UTC)

Spectral classes
Can someone explain why 2MASS J0523-1403 is a spectral standard for L1-type main sequence stars? Cause it is actually an L2.5 star, as it says in the Wikipedia article about the star and in most sources. And it has a mass of 0.06 solar masses, not 0.07. The temperature is 2074 K, not 2200 K. It's the same for many of the other "spectral standards" in the table, for example, the B0 star has a too-low mass and a too-high luminosity, the B5 star is practically a subgiant, and the F0 star has a too-low mass and too-low temperature! All of the stars in EZ Aquarii are more M7 than M5! Please fix the table! Jtadesse (talk) 17:28, 5 December 2023 (UTC)