Talk:Epsilon Aurigae

Epsilon Aurigae has been listed as one of the Natural sciences good articles under the good article criteria. If you can improve it further, please do so. If it no longer meets these criteria, you can reassess it.

Article milestones
Date	Process	Result
March 10, 2009	Good article nominee	Listed

Optical components

I have removed the following sections from the infobox - as far as I can tell these stars appear not to be physically associated with the Epsilon Aurigae system but instead are merely located close to the same line-of-sight as viewed from Earth. Furthermore the information given is incorrect - the observed separation has been mapped to semimajor axis, and the position angle has been entered as inclination. Icalanise (talk) 22:50, 15 January 2009 (UTC)[reply]

Orbit
Companion	CCDM 05020+4350 B
Semi-major axis (a)	21.2″
Inclination (i)	224°
Orbit
Companion	CCDM 05020+4350 C
Semi-major axis (a)	43.0″
Inclination (i)	275°
Orbit
Companion	CCDM 05020+4350 D
Semi-major axis (a)	46.2″
Inclination (i)	317°
Orbit
Companion	CCDM 05020+4350 E
Semi-major axis (a)	48″
Inclination (i)	207.6°

Conflicting Information

In the introductory paragraph it reads that Epsilon Aurigae has a period of 9890 days while on the sidebar on the left it reads it only has a period of 9888 days. Im not sure which number is correct, but we should at least make both numbers the same, what does everyone else think? —Preceding unsigned comment added by Chuck61007 (talk • contribs) 20:45, 23 March 2009 (UTC)[reply]

The correct period is slightly wavelength dependent, but the value of 9885 (Huang, 1974) is commonly accepted. See the article by Webbink (http://adsabs.harvard.edu/abs/1985NASCP2384...49W) in the 1985 conference proceedings on Eps Aur for further information. —Preceding unsigned comment added by Bborgman (talk • contribs) 23:48, 28 October 2009 (UTC)[reply]

Planning to Fix Lots of Stuff

Dear Wikifriends, I plan to so some fixing. Now that Epsilon Aurigae is about to start its long-awaited eclipse, this page will have many more visitors. The article is full of grammatical errors, which I will fix as soon as I get a . Unless there are objections fairly soon, I also plan to eliminate some of the redundancies in the article, and hopefully we can do some other cleaning up as well. Vegasprof (talk) 16:21, 1 August 2009 (UTC)[reply]

I made the changes I planned to, but now there are inconsistencies. My source on Eps Aur A's diameter and luminosity are different from what is currently in the article. Vegasprof (talk) 23:04, 5 August 2009 (UTC)[reply]

Companions

Smells like έ Aur is a triple star with έ Aur A + έ Aur B $and$ C(B and C-contact binary) —Preceding unsigned comment added by 91.79.176.98 (talk) 07:41, 24 April 2011 (UTC)[reply]

dark companion

Apparently the dark companion was hailed as the largest (diameter) known star, incorrectly attributed to being a star, in 1970... that might be useful in a history section.

Ottawa Citizen, Ask Andy: The Biggest Star, American Family Features, Fri 27 Nov 1970, p.44

65.94.47.63 (talk) 11:15, 13 June 2011 (UTC)[reply]

Mass

The mass of the visible star is 2-3 times that of Sun and it's a supergiant. The mass of the hidden object is 6 solar masses and it's a main sequense star. The problem is how did the lighter star evolve faster than the heavy. Moreover the other facts (radius, luminosity) point that the visible star has a mass around 9 to 15 solar masses.--C messier (talk) 15:53, 21 August 2011 (UTC)[reply]

One word: mass transfer :lol: Seriously though, despite the mass transfer that is undoubtedly important those numbers are barely more than guesses. Lithopsian (talk) 15:48, 15 August 2012 (UTC)[reply]

Spitzer et al

The luminosity class and associated data for this star has recently been changed to reflect studies by Hoard et al indicating a fairly low mass post-AGB (very large) giant star. This is essentially the "low mass model" first suggested in the mid 1980s. Although this is presented in the article as a fait accompli, it is hardly a consensus view. At least two papers have been published since producing much higher distance, luminosity, and mass estimates than the Hipparcos value adopted as being consistent with the low mass model. It must be noted that the error range associated with the Hipparcos parallax is so large that any distance between about 400 and 4,000 parsecs is likely, so the adopted value of 625 parsecs should be considered as a possibility but not as a fact. Talk on, but barring new evidence I will be changing the article to at the very least reflect the fact that there are still two distinctly different models of the system. Lithopsian (talk) —Preceding undated comment added 16:31, 15 August 2012 (UTC)[reply]

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Mass confusion (related to "Spitzer" talk)

The mass confusion (no pun intended) is as follows:

From the "Nature of the system" section:

"The main problem with [the high mass] model is the nature of the secondary, which is required to have a mass about the same as the primary, at odds with observations where it appears as a B-type main sequence star. The secondary may be a close binary involving two lower-mass main sequence stars, or a more complex system.

The low mass model, recently popularised by the Citizen Sky project, proposes that the primary is an evolved asymptotic giant branch star of 2–4 M☉. This relies on distance and luminosity estimates lower than most observations. The star would be an unusually large and bright giant star for the given mass, possibly as the result of very high mass loss. To match the observed eclipse and orbital data, the secondary is a fairly normal B main sequence star of about 6 M☉ embedded in a thick disc seen nearly edge on."

From the infobox:

Mass (A): 2.2 - 15, (B): 6 - 14.

The high masses, ~15 and 14 solar masses (Upsilon Orionis is of type B0V and heavier) don't look "at odds" with about equal masses. In fact, the low-mass model is a far worse fit with ~4 and ~6 solar masses, exacerbated by the fact that those two are the extreme values which result in the best fit possible, i.e. B is at least 50% more massive than A. If at all, it looks like the low-mass model is less plausible except if the dynamics require that B is the more massive partner.

An unrelated edit: I corrected the luminosity figures to the sourced values used in the infobox. There seemed to be a factor of two somewhere, which resulted in too high a value. - ¡Ouch! (^{hurt me} / _{more pain}) 15:56, 6 July 2017 (UTC)[reply]

Needs less original research (ie. don't over-think it) and a bit looser wording. The "equal masses" is really really approximate, barely more than order of magnitude. The actual relation is the binary mass function, the value of which is well known. At low system masses, the B star is more massive, but at high system masses, it is slightly less massive. I changed the wording. Feel free to elaborate, but remember to give reliable sources, something which the article is currently somewhat lacking. I'm also going to scrap the Spitzer section completely (this is an encyclopaedia article, not a soap opera) and clarify further when describing the masses in the following section (and add some citations!) Lithopsian (talk) 21:01, 6 July 2017 (UTC)[reply]

It is confusing, especially as some of the high mass model(s) seem to have different masses etc. ok...time for overhaul...agree the removed section was on the wordy size, although the evolution of the models is an interesting story. I remember talk of it being a black hole when I was a kid. Cas Liber (talk · contribs) 21:28, 6 July 2017 (UTC)[reply]

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