Talk:Variable star

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[edit] Our own Sun

Our own Sun is a good example which goes through practically no measurable variation in brightness.

This is untrue. At present, there is a 0.1% variation between solar max and solar min years in the solar cycle. There is some evidence of greater variation on longer time scale. This is small, and much smaller than stars that are classified as "variable". But it is easily measured even with fairly crude apparatus. I have somewhat changed the offending sentence that was stated on this site. Securiger 00:45, 13 Aug 2004 (UTC)

[edit] Spectrum Variables

Is there a good reason why spectrum variables are not included?

[edit] Reasons

It would be nice if the article actually provided some explanations of the reasons that the stars change their luminosity. Paranoid 20:09, 17 August 2005 (UTC)

[edit] Naming of variable stars

This system of nomenclature was developed by Friedrich W. Argelander, who noted that many variable stars were red and so began the naming with the letter R for rot (Red).

Is this really so? As far as I know, Argelander chose letter R as the first letter because the last letter used in Bayer designation scheme was Q. Bayer designations start from α and continue to ω. After the Greek letters were exhausted, lower case letters were used, and finally came the upper case letters. Non-Greek letter designations have largely fallen out of use. Few expections remain, h Persei (open cluster), e Eridani (not ε/epsilon!), and P Cygni. The last one is not a variable star name, although P Cygni is about as variable as a star can be.--Jyril 14:31, 6 November 2005 (UTC)

That's what I thought too. Don't have a citation offhand but I'm pretty sure that you're correct. JYolkowski // talk 17:36, 6 November 2005 (UTC)
I found it! Argelander wrote:
" I name R the star in the Virgin whose periodic variability was discovered in 1809 by Harding... I hope I will be forgiven for taking the liberty of designating by a letter a star which does not appear in the Bayer catalogue but it seems to me that owing to their originality, variable stars are entitled to claim such a distinction. To my mind, a particular name seems to be almost unavoidable to allow an easy identification of stars that are frequently mentioned. But in order to avoid confusion with the alphabetic designation of Bayer, I chose to use the last letters of the alphabet only and to write them in capitals... "
Source: [1]
--Jyril 18:32, 6 November 2005 (UTC)

[edit] General structure of this article

I think the general structure of this article may be improved. What I expect the "general visitor" of this article to look for would be more of a general introduction to the subject, giving insight in the first place, and less of a comprehensive catalogue of variable types. The article in its new form may consist of two parts:

  1. General introduction, including broad distinction between intrinsic and eclipsing/rotating variables; discovery history; observational data (kinds of variability, light curve, spectrum, magnetism, etc., and what may be learned from them); theoretical tools (why do stars pulsate; Eddington's "wave equation"); nomenclature system;
  2. General classification scheme. The present catalogue largely reflects the General Catalogue of Variable Stars (GCVS) ordering, which is often alphabetical; instead a more illuminating ordering would be based on physical criteria (such as type of star--main sequence, giant, protostar, white dwarf; or radial vs non-radial pulsations). The list should not be too detailed (the GCVS has some 115 categories and subcategories); instead, links to (new) wikipedia articles such as "intrinsic variable"; "rotation variable"; "eclipsing variable" should refer those interested to a more comprehensive treatment.

I will try and make these amendments to the Dutch nl.wikipedia article first; if this is an improvement I propose a similar restructuring of this English article. Hans van Deukeren 16:38, 1 February 2006 (UTC)

Thanks for all your work on this article Hans.--Kalsermar 18:10, 5 March 2006 (UTC)

[edit] Why is a link to the Heinlein/Robinson book "non appropriate"?

It is conceivable someone looking for the book will go to "Variable star" rather than "Variable Star". --Lukobe 20:35, 24 July 2006 (UTC)

It is imho actually very unlikely that someone would look for that book in that way. Rather, they'd probably go to the author's page and go from there. Other than that, making a true Variable star (disambiguation) might be better, others can correct me on this if I'm wrong.--Kalsermar 21:10, 24 July 2006 (UTC)
I already created Variable Star as such a disambiguation page. I suppose that may be enough. --Lukobe 21:34, 24 July 2006 (UTC)
Sounds good to me :-) --Kalsermar 23:53, 24 July 2006 (UTC)
Lukobe got rid of the dab page, and redirected it directly to Heinlein's novel. Now there's a vote on to MOVE the Heinlein page to Variable Star, by Lukobe as a matter of fact, after already discussing it here! I've restored the dab, at the moment. Vote at Talk:Robert A. Heinlein's Variable Star to discuss the requested rename. 132.205.93.88 23:52, 31 July 2006 (UTC)
Note the proposal is to move the Heinlein page to Variable Star NOT Variable star. And this is because the book's name is not actualy Robert A. Heinlein's Variable Star, which is where the book currently resides. --Lukobe 00:57, 1 August 2006 (UTC)

[edit] 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)