Talk:Capella

message: The "Akkadian" line info should be deleted entirely; it has nothing to do with Capella and is seriously out of date. What the writer has transliterated as Dilgan iku should be read: Sumerian aš.iku "1 iku (measure)" lent into Akkadian as ikû. An iku is the basic Sumerian measure of square area, ca. 3528 sq. meters. The celestial iku refers to the big square figure within the constellation Pegasus, i.e. α, β, γ Pegasi plus α Andromedae. Dubsarmah 16:06, 26 October 2007 (UTC)
thread_title: Comments

message: The claim that Capella is part of an aboriginal constellation is puzzling. If Capella is very close to the Pole Star, how is it visible in the southern hemisphere?  —Preceding unsigned comment added by 66.165.176.60 (talk) 17:06, 15 September 2008 (UTC)
replies: text: It is - I live in southeastern Australia and Capella is quite high enough to be visible here. Casliber (talk · contribs) 00:32, 17 February 2009 (UTC)
thread_title:  Australian Aborigines can See Capella? 

message: Unreferenced material re Persian names moved from article: "In Persian literature, Capella (Bozbān, Ayyuq) is a metaphor for a huge distance and also the light red colour...Other names used by other cultures include: ... in Persian, بزبان, Bozbān (English: goat-keeper) and نگهبان, Negahbān (English: guard)..." Spacepotato (talk) 19:44, 10 January 2009 (UTC)
thread_title: Unreferenced material

message: Is anyone working on the issues brought up in the GAN review? It's been a week, and nothing has been done. Unless something happens in the next day or two, I will fail the article. Ealdgyth - Talk 18:48, 5 March 2009 (UTC)
replies: text: You have a 30" monitor? I am jealous.....but seriously. I know a little bit and can help but it needs some of the experts to chip in too. Casliber (talk · contribs) 22:25, 5 March 2009 (UTC)
replies: text:  Photographer. More monitor means less eyestrain when developing pictures. I'd hate to fail the nomination, but I certainly can't address some of the above issues. Ealdgyth - Talk 22:29, 5 March 2009 (UTC)
thread_title:  GAN 

message: Capella (α Aurigae, α Aur, Alpha Aurigae, Alpha Aur) is the brightest star in the constellation Auriga, the eleventh brightest star in the night sky and the third brightest star in the northern celestial hemisphere, after Arcturus and Vega
Why is Sirius not in the above list? Jprw (talk) 21:46, 19 October 2012 (UTC)
replies: text: Because it is actually located in the southern celestial hemisphere, about 16 degrees south of the sky equator - which still makes it visible for much of the year as far north as the UK and central Europe. - Incidentally, the article here indicates that Capella and (just before it) Aldebaran were the brightest stars in all of the sky around 200.000 years ago, but the outlook on the future of the two Capella stars also hints that they will become even brighter over the next couple million years, as they both swell into red giants. So in perhaps six or ten million years time, Capella may once again have become the brightest star in the earth's sky (Canopus, another main contender, will apparently have receded in apparent magnitude within a million years or two - see the WP article on that star, which probably also borrows from Schaaf). 83.254.151.33 (talk) 02:04, 9 May 2013 (UTC)
thread_title: Sirius omission

message: The opening paragraph states:
"Although it appears to be a single star to the naked eye, it is actually a star system of four stars in two binary pairs. The first pair consists of two bright, large type-G giant stars, both with a radius around 10 times that of the Sun and two and a half times its mass, in close orbit around each other. Designated Capella Aa and Capella Ab, these two stars have both exhausted their core hydrogen fuel and become giant stars, though it is unclear exactly what stage they are on the stellar evolutionary pathway."
But under "Characteristics" it says:
Aa
Spectral type	K0III[4]
Ab
Spectral type	G1III[4]
So Is Capella Aa a type G or a type K star?  — Preceding unsigned comment added by 86.155.239.6 (talk) 14:42, 26 November 2015 (UTC)
replies: text: Most sources have it as two G-type stars, but one is nearly into K spectrum. I was buffing this article a while ago and plan to return to it to tidy up a bunch of things like best consensus on spectral type etc. Cas Liber (talk · contribs) 23:30, 26 November 2015 (UTC)
thread_title: Spectral type

message: The interesting info that Capella used to be the brightest star in the sky around 160k-210k years ago is sourced to "Schaaf 2008" but there's no proper reference to just what article this is. Some reference note that used to be placed before the current notes 21-22 has been removed by accident, and those two references have become orphaned. 83.251.170.27 (talk) 13:53, 7 March 2016 (UTC)
thread_title:  Orphaned references 

message: Substituted at 10:50, 29 April 2016 (UTC)
thread_title: Assessment comment

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thread_title:  External links modified 

message: , do you think there is anything else missing from this article before throwing it to the wolves at FAC? cheers, Cas Liber (talk · contribs) 23:21, 16 March 2017 (UTC)
replies: text: I can't think of any significant subjects that are missing. I could write more about the evolutionary state and the discoveries of the visual components, but I'm not sure it is necessary. I've added a couple of images, but perhaps one or two more could still be useful. Do you think there are any areas we need to look at before submission? Lithopsian (talk) 15:16, 17 March 2017 (UTC)
replies: text: The image :File:Capella-Sun comparison.png bothers me a little in that Aa is paler than Ab I guess. But I guess one could write that off as luminosity. I couldn't see any other images that were useful on commons. Need to think about this...I did worry about the flow. Taking another look now. Cas Liber (talk · contribs) 19:42, 17 March 2017 (UTC)

text: The only other thing I guess is adding what Capella Aa will be doing on its evolutionary path. So it should be heating up...? Cas Liber (talk · contribs) 19:57, 17 March 2017 (UTC)
replies: text: No, likely it is cooling down. It is widely considered to be in a clump giant, but the most recent guesses put it at the end of that phase, running out of helium in its core. Next stop the asymptotic giant branch where it will be an M star. Descriptions are often vague and probably a bit sloppy. I've seen it referred to as "post helium-flash" when it quite clearly is too massive for that and, as you just described, too small. It ought to have ignited its core helium smoothly, and as a smaller less luminous star than those that reach the tip of the red giant branch and undergo a flash. I can't find a good reference that says these things explicitly but I don't think they're in any doubt. Strictly, on that basis, it isn't even a clump giant, but it is pretty close and sits in the same part of the HR diagram. Lithopsian (talk) 21:04, 17 March 2017 (UTC)
replies: text: I just realized we hadn't covered the rotational velocities and large difference in spin - added now. I can't think of anything else. Cas Liber (talk · contribs) 21:09, 17 March 2017 (UTC)
thread_title:  Pre-FAC check 

message: So far as I know, a Hertzsprung-Russell diagram has temperature = color as the x-axis.  There can't be two colors for one kelvin temperature.  But the diagram in this article has a yellow line next to the red line for the red giant branch.  I think this must be an error. Wnt (talk) 11:29, 21 March 2018 (UTC)
replies: text: I assume you're talking about the image titled "Evolution of Capella giants"?  It has only one line, coloured differently at different phases in the evolution of a (roughly) two-solar-mass star.  The colours are used both as an aid to separating different segments of the evolutionary track when they are very close to eachother and also as a rough indicator of the colour/temperature of the star during that phase.  There is no error.  Lithopsian (talk) 14:58, 21 March 2018 (UTC)
replies: text:  How can the star have different colors when it's at the same color temperature?  Compare the figures above. Wnt (talk) 23:33, 23 March 2018 (UTC)
replies: text: You seem to be looking at a different diagram to me.  Double vision?  Too much beer?  What star are you talking about having two different colours?  There is no such thing on the diagram.  Explain the problem in more detail, please.  There are two stars on the diagram, but they are two different stars.  Lithopsian (talk) 12:47, 25 March 2018 (UTC)
replies: text: The orange curve under the writing "Capella Aa", and the yellow curve directly above it. Wnt (talk) 03:45, 28 March 2018 (UTC)
replies: text: Yes, two parts of a single evolutionary track for a  star.  What's the problem?  The colours?  The track itself?  That star locations?  Lithopsian (talk) 15:56, 28 March 2018 (UTC)
replies: text: I mean yes strictly speaking it would have been good to have some sort of exact gradient of colour, but I think the colours of the pathways illustrates it well. Could always add a disclaimer I guess...Cas Liber (talk · contribs) 20:33, 28 March 2018 (UTC)
thread_title:  Colors on H-R diagram 

message: The article says that Capella has 2 bright components Aa and Ab but nowhere is their most obvious and relevant attribute - their angular separation - given. The first thing someone looking Capella in a telescope wants to know is, can he expect to see these 2 separate stars.Paulhummerman (talk) 03:25, 3 December 2020 (UTC)
replies: text: They are pretty close!  The semi-major axis of the orbit is given in the starbox.  Their separation is given in km in the text, but not in arc-seconds.  That might be the best place to give the angular separation, but maybe you think somewhere else would be better.  Lithopsian (talk) 17:15, 3 December 2020 (UTC)
thread_title:  Angular separation of Capella Aa and Ab?