Talk:B-type main-sequence star: Difference between revisions

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:There is a good difference between theory and practice. While it would naturally be expected that a luminosity class reflects the actual evolutionary stage, this is not always the case, like [[55 Cancri]], [[Gliese 777]], [[Gamma Cephei]], [[Mu Ceti]], [[Delta Capricorni]], [[Merak (star)|Merak]], [[Rasalhague]], [[23 Ursae Majoris]], [[Menkalinan]] and [[Kepler-410]] and many more that are main sequence stars in evolutionary terms, but were assigned IV or V-IV luminosity classes based on the spectrum. [[User:21.Andromedae|21 Andromedae]] ([[User talk:21.Andromedae|talk]]) 12:57, 18 January 2026 (UTC)

::The reply above by 21.Andromedae included [[Kappa Andromedae]], but was deleted because it ‘”now has a main sequence luminosity class”<nowiki/>’ (you can also write [[Kappa Andromedae|<s>Kappa Andromedae</s>]] btw, makes it much easier to reply to a post that was changed late in time). [[User:Stevinger|Stevinger]] ([[User talk:Stevinger|talk]]) 10:08, 21 January 2026 (UTC)

::The reply above by 21.Andromedae included [[Kappa Andromedae]], but was deleted because it ”now has a main sequence luminosity class”<nowiki/>’ (you can also write [[Kappa Andromedae|<s>Kappa Andromedae</s>]] btw, makes it much easier to reply to a post that was changed late in time). [[User:Stevinger|Stevinger]] ([[User talk:Stevinger|talk]]) 10:08, 21 January 2026 (UTC)

::And to add to the already extensive list of examples: [[Nu Indi]], [[GJ 2030]], [[Chi Leonis]], and [[171 G. Puppis]]. [[User:21.Andromedae|21 Andromedae]] ([[User talk:21.Andromedae|talk]]) 22:55, 20 January 2026 (UTC)

::[[R136a1]] and many similar massive stars, most (effectively all, but not all classified in Wikipedia as main sequence with references) cool subdwarfs (eg. [[GJ 1062]] and [[Mu Cassiopeiae]] – possibly not a clean example but definitely a main sequence star considered to be a subdwarf). Am I too cynical to think that half of these are going to get edited in the next day or two? Seriously, are you here to push an agenda or to improve the wiki?

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To me it was a really, really bad idea to move this from “B-type main sequence star” to “B-type main sequence” because there is no such thing as a “B-type main sequence”. The article name may now cause unnecessary confusion. It should have been discussed first. Regards, RJH (talk) 18:40, 21 March 2012 (UTC)[reply]

There is a move discussion in progress on Talk:A-type main sequence star which affects this page. Please participate on that page and not in this talk page section. Thank you. —RMCD bot 22:44, 24 April 2013 (UTC)[reply]

One of the most important properties of B-type main sequence stars is missing: what is their luminosity? “extremely luminous and blue” in the current version is vague. Bkocsis (talk) 11:42, 18 March 2020 (UTC)[reply]

I would add that these stars transition to helium fusion more smoothly than solar mass stars, which experience a degenerate helium flash. 74.135.194.87 (talk) 16:57, 27 January 2024 (UTC)[reply]

Discussion is at Talk:A-type main-sequence star#Circumstellar discs in the planets section. 21 Andromedae (talk) 20:39, 12 November 2025 (UTC)[reply]

I have to address the ‘The spectral luminosity class is typically V’ again. Thank you for bringing forward examples like V372 Carinae and discussing it, @Lithopsian, @21.Andromedae. However, the statement is still incosistent with the definition of luminosity class, which was my original worry. You can compare to the Main sequence article that e.g. has a line ‘These main-sequence stars, or sometimes interchangeably dwarf stars, are the most numerous true stars in the universe and include the Sun.’ In case other Wikipedia pages are not a source you want to see, I looked it up in the IAU Office of Astrononomy for Education (OAE) page at astro4edu.org: ‘Roman numerals are used to denote luminosity class: Stars on the main sequence burning hydrogen are classified as dwarfs (V)’ [1], ‘ “Dwarf star” is a synonym for a star on the so-called main sequence’ [2]. (The terms and their definitions on the pages have been approved by a research astronomer and a teacher.)

In case none of you disagrees I will delete the ‘typically’ from the corresponding pages. Stevinger (talk) 05:48, 18 January 2026 (UTC)[reply]

There is a good difference between theory and practice. While it would naturally be expected that a luminosity class reflects the actual evolutionary stage, this is not always the case, like 55 Cancri, Gliese 777, Gamma Cephei, Mu Ceti, Delta Capricorni, Merak, Rasalhague, 23 Ursae Majoris, Menkalinan and Kepler-410 and many more that are main sequence stars in evolutionary terms, but were assigned IV or V-IV luminosity classes based on the spectrum. 21 Andromedae (talk) 12:57, 18 January 2026 (UTC)[reply]

The reply above by 21.Andromedae included Kappa Andromedae, but was deleted because it now has a main sequence luminosity class‘ (you can also write ~~Kappa Andromedae~~ btw, makes it much easier to reply to a post that was changed late in time). Stevinger (talk) 10:08, 21 January 2026 (UTC)[reply]

And to add to the already extensive list of examples: Nu Indi, GJ 2030, Chi Leonis, and 171 G. Puppis. 21 Andromedae (talk) 22:55, 20 January 2026 (UTC)[reply]

R136a1 and many similar massive stars, most (effectively all, but not all classified in Wikipedia as main sequence with references) cool subdwarfs (eg. GJ 1062 and Mu Cassiopeiae – possibly not a clean example but definitely a main sequence star considered to be a subdwarf). Am I too cynical to think that half of these are going to get edited in the next day or two? Seriously, are you here to push an agenda or to improve the wiki?

More seriously, at the risk of opening a huge POV can of worms, luminosity class might benefit from some discussion of the matches and mismatches with evolutionary stages of the same or similar name. Reliable references needed of course, which might be hard to find for some cases: the massive stars and cool subdwarfs should be simple enough, perhaps also some for giants and supergiants which bear almost no relation between the luminosity class and the underlying physical state of the star. Perhaps simple explanations of the basis for derivation of spectral luminosity classes and the definition of the related evolutionary state might be sufficient for the subtler cases that we’re arguing about here. There’s a little bit there now, but it is all sort of vague. Lithopsian (talk) 16:15, 21 January 2026 (UTC)[reply]

I suggest taking that as disagreement and moving on to something more constructive. Lithopsian (talk) 15:56, 18 January 2026 (UTC)[reply]

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