Talk:Variable star

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H-R diagram illustration

As a suggestion, it may be beneficial to include an illustration of an H-R diagram showing the regions where various types of variability occur. I've seen this illustrated in astronomy textbooks, as well as some web sites. Here are some examples (which I'm sure could be improved upon):

http://www.astro.uiuc.edu/~kaler/sow/hrv.jpg

http://ircamera.as.arizona.edu/astr_250/images/hr_vars.gif

http://outreach.atnf.csiro.au/education/senior/astrophysics/images/binvar/hrpulsvar.jpg

http://universe-review.ca/I08-14-variables.jpg

http://www.astronomy.org.nz/aas/Journal/Nov2004/images/Instability%20Strip%202.gif

http://www.dil.univ-mrs.fr/~gispert/enseignement/astronomie/3eme_partie/variables_img/diagHR.gif

Thank you. — RJH (talk) 19:10, 16 May 2007 (UTC)[reply]

Thanks a lot. Good starting point. Said: Rursus (☻) 16:43, 24 September 2008 (UTC)[reply]

Does look so-so only: the HR diagram is cluttered with texts, often with the TLA disease. I'll ponder how to improve. Said: Rursus (☻) 14:16, 15 October 2008 (UTC)[reply]

You might want to give it a new try based on http://www.helas-eu.org/outreach/index.php?option=com_content&task=view&id=17&Itemid=46 (however, pulsating stars only, not all variables generally) Bruddl (talk) 16:29, 20 May 2010 (UTC)[reply]

I like the diagram, almost essential in this article. It could probably stand a few additions for recent discoveries. I don't see TLA as a problem provided the acronyms are also clearly visible in the text. You could also explicitly key them at the bottom of the diagram itself. With full names that don't completely crowd eachother out, it would almost certainly need to be bigger and the version in the article would become an unreadable thumbnail. Lithopsian (talk) 14:54, 26 February 2013 (UTC)[reply]

Discovery Incorrect 1^ST para

The first paragraph in section Discovery have decidedly got it in quite another way that I got it, namely:

The occurrence of Tycho's Star and Tycho Brahe's subsequent studies, showed that the fixed heaven is not as "fixed" as was previously believed. Fabricius described omicron Ceti as a nova. It was Holwarda that discovered that omicron Ceti was pulsating, and he determined the period to 11 months.

I suggest a rewrite to clarify. Said: Rursus (☻) 09:35, 20 October 2008 (UTC)[reply]

Extrinsic/Intrinsic

Extrinsic/Intrinsic ― I suspect this division might be obsolete. Said: Rursus (☻) 19:14, 31 October 2008 (UTC)[reply]

AAVSO divides like this:

extrinsic
eruptive
intrinsic

Patrick Moore divides like this:

extinsic:

eclipsing vars

intrinsic:

rotating vars
...

GCVS has nothing like "trinsic" whatsoever. It might be a confused term that have fallen out of usage becåse of confusion and/or new knowledge. In my opinion the rotavars are variable due to one "extrinsic" (geometric) and one "intrinsic" (real physical variability) mechanism. The ellipsoids are also "semi-intrinsic", since the stars deform each other physically. Said: Rursus (☻) 19:50, 31 October 2008 (UTC)[reply]

Stars such as the RS Canum venaticorum variables also blur the distinction between intrinsic and extrinsic variables, as potentially do several other types. I would like to get rid of these sections, although they may seem like nice groupings for a lay reader. Even for the lay reader, the existing depth of nesting of the subsections is probably intimidating. Lithopsian (talk) 00:01, 26 February 2013 (UTC)[reply]

List of var discoveries

Acc2 Patrick Moore (The Guinness Book of Astronomy), the discovery list is:

1	Mira	Holwarda	1638
2	Algol	Montanari	1669
3	χ Cyg	Kirch	1686
4	R Hya	Maraldi	1704
5	α Her	W. Herschel	1759
6	μ Cep	W. Herschel	1782
7	R Leo	Koch	1782
8	δ Cep	Goodricke	1784
9	β Lyr	Goodricke	1784
10	η Aql	Pigott	1784

That makes 10 before 1786, unless Moore (and so me) missed some. Said: Rursus (☻) 19:44, 1 January 2009 (UTC)[reply]

List of variable stars supports 10 before 1786, unless supernovae are counted. Said: Rursus (☻) 20:27, 1 January 2009 (UTC)[reply]

Cataclysmic/Explosive

The RASC lists four sub-categories of variable stars, compared to five here. They put the cataclysmic and explosive variables under "Eruptive variables". The AAVSO has a similar organization. I'd like to suggest merging the Cataclysmic/Eruptive section under the "Eruptive variables" section.—RJH (talk) 19:58, 9 November 2009 (UTC)[reply]

I think it would be better to keep the current five classes (eruptive, pulsating, cataclysmic, rotating, and eclipsing) as they are the first five classes used by the GCVS [1] and by Sterken and Jaschek (ISBN 0521390168). (These sources also have a sixth class of variable X-ray sources which no-one has bothered to list here.) Spacepotato (talk) 00:53, 10 November 2009 (UTC)[reply]

Okay. In that case the Cataclysmic variable star article probably shouldn't be listed as the main article for it's section as it doesn't cover Type II supernovae.—RJH (talk) 00:06, 14 November 2009 (UTC)[reply]

In case anyone gets itchy about this topic in the future, the AAVSO now groups variables under the same five categories. Don't know if that is Wikipedia changing the world or just a coincidence. Makes sense anyway. Lithopsian (talk) 23:50, 25 February 2013 (UTC)[reply]

Section grouping

I've added several new variable types to this article, all pulsating variables. So now we have a fairly long list with little structure to it. I could group maybe three or four of them as main sequence variables, or perhaps a slightly different three as B type variables or some such. Any other ideas? Lithopsian (talk) 23:53, 25 February 2013 (UTC)[reply]

@Lithopsian: Perhaps a grouping for pulsating variables with temperatures higher than in the instability strip? Thus, Beta Cephei variable, Slowly pulsating B-type star, and PV Telescopii variable. Or perhaps pulsators outside the instability strip? Or there could be a category for supergiants. I'm not sure what you'd call them. Praemonitus (talk) 16:27, 9 September 2025 (UTC)[reply]

I'm not sure that grouping under supergiants makes sense: the four types I can see mentioned are completely unlikely eachother. I can see grouping "cool" pulsating variables together; they are all evolved large stars, although some are on the asymptotic giant branch, and some supergiants, possibly plus RV Tauri stars. Then maybe group the "hot" variables also. Perhaps not the white dwarfs?

Okay, that works for me. The AAVSO doesn't divide them further, so maybe it's arbitrary on our part.[2] Praemonitus (talk) 22:23, 9 September 2025 (UTC)[reply]

Are long secondary period variables really a separate class? Or just a type of variation that occurs in a number of cool pulsating variables?

Not that I can see, they just appear to be a variant of the higher level long-period variable star. The text should probably be merged into that section's introduction. I was "bold" and performed the merge. Praemonitus (talk) 22:23, 9 September 2025 (UTC)[reply]

On a different tack, what does grouping them achieve? Various types of Cepheid are already technically nested under "Cepheids and cepheid-like variables" (should "cepheid-like" be capitalised?), but visually the reader sees just a confusing sequence of sections. Or at least I see no difference between the fourth and fifth level section headers. Lithopsian (talk) 20:10, 9 September 2025 (UTC)[reply]

Grouping them by general function makes sense; beyond that I'm not sure. Like you note, it's difficult to see the hierarchy based solely on the headers. I had a notion about using Smallcaps for the triple '=' headers, but that's non-standard. Praemonitus (talk) 22:06, 9 September 2025 (UTC)[reply]

I had the idea to address this via definition lists. This makes the grouping (somewhat) more apparent. Praemonitus (talk) 15:04, 10 September 2025 (UTC)[reply]

Assessment comment

The comment(s) below were originally left at Talk:Variable star/CommentsTalk:Variable star/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

I lowered this from B-Class to the new C-Class due to it not having sufficient inline references. WilliamKF (talk) 16:37, 13 July 2008 (UTC)[reply]

Last edited at 16:37, 13 July 2008 (UTC). Substituted at 09:49, 30 April 2016 (UTC)

The references issue has been covered although the article might be considered incomplete as I'm not sure it covers all the topics in Category:Variable stars. (For example, FS Canis Majoris variable or Lambda Eridani variable.) Praemonitus (talk) 16:18, 9 September 2025 (UTC)[reply]

Microvariability

Please could somebody edit this article cover the topic of microvariability? Thank you. Praemonitus (talk) 22:40, 13 March 2017 (UTC)[reply]

Unusual Variables

Are there unusual variable types, such as a black hole orbiting a star? Maybe a neutron star orbiting a red supergiant? I was wondering if there is any unusual and rare types in the universe. AstronomyKid1 (talk) 16:30, 21 November 2024 (UTC)[reply]

I've added a section on variable X-ray sources, which would cover the topic of an interactive binary with a black hole component. Praemonitus (talk) 16:14, 9 September 2025 (UTC)[reply]