Talk:Asymptotic giant branch

Timescales

This article would benefit from having more information about timescales. For instance, how long is the interval from RGB to AGB.129.21.55.82 (talk) 19:11, 30 January 2009 (UTC)

"as large as one astronomical unit"

Probably meant to say "in radius", but the naïve might assume "in diameter." This is vague at best and wrong at worst, since isn't even Sol expected to get bigger than 1AU radius in several billion years? --Polymath69 13:33, 17 August 2007 (UTC)

"surficide reactions"? - wouldn't surface chemical reactions be better? As it is, it sounds like your talking about the results of murdering surfers. 144.137.116.114 (talk) 07:23, 17 May 2008 (UTC)Jim Jacobs.

Nah. Point break on Rocheworld. Be there or B² ;) Wnt (talk) 23:22, 6 July 2008 (UTC)

Apparent contradiction

The diagram in this article shows stars moving horizontally from the main sequence to supergiant status. The diagram shown in most of the other articles, e.g. giant star, shows the supergiants far higher in absolute magnitude. Please reconcile or clarify this. Wnt (talk) 05:21, 30 June 2008 (UTC)

The supergiants are in roughly the same position in both diagrams. In Image:Stellar evolutionary tracks-en.svg, the luminosity of the 15 solar-mass track is shown as approximately 3·10⁴ solar luminosities. In Image:HR-diag-no-text-2.svg, the absolute magnitude of luminosity class Ia is shown as around −7. Since 4.83 − 5 log₁₀₀ (3·10⁴) = −6.36, you can see that the positioning is approximately the same. Spacepotato (talk) 17:37, 6 July 2008 (UTC)

You're right - the distinction is actually that the stars starting these horizontal paths are 30,000 K or hotter class O stars, which are extremely rare. The main sequence in the second link or at [1] stops at class B and doesn't include class O. Wnt (talk) 23:17, 6 July 2008 (UTC)

Hmm, thinking for a while about it: I think it's confusing that the image in Giant star and the image of this article regards different evolutional states of the stars. The image in this article draws a line along Zero Age Main Sequence, since the article is about star evolution; non-evolutionary HR-diagrams use to draw a line along main sequence which is some kind of mean evolutionary position. For most of the main seq the distance to ZAMS is small and constant, but becomes increasingly large for very massive stars, making ordinary HR-diagrams have kind of an upwards curve, which gives the impression of steeper increase of luminosity for "early" MS stars. Said: Rursus (☻) 14:16, 17 September 2008 (UTC)

Merge

I've just merged the stub article Asymptotic giant branch star into this article, and left a redirect there. Wdfarmer (talk) 09:23, 14 August 2008 (UTC)

Yech!

Text says:

AGB CSE

I say: ATOTLAS! (All these obnoxious three letter abbreviation stinks). IAU should imitate the nomenclature style of IUPAC. Said: Rursus (☻) 13:26, 17 September 2008 (UTC)

Circumstellar envelopes of AGB stars - units

In the "Circumstellar envelopes of AGB stars" section there is a calculation that starts from 10 km/s and ends in 10¹⁹ cm. I see no reason to have the figure as 10¹⁹ cm rather than 10¹⁷ m, 10¹⁴ km or even 100 Pm (Peta-meters). I would like to change this, but I don't know if there is some reason cm is used. If anyone out there has an objection to changing it to 10¹⁷ m, especially someone with an astronomy background, please let me know. Otherwise, I plan to change this before the month is out. Lon of Oakdale (talk) 22:29, 3 October 2008 (UTC)

LAGB?

How does LAGB phase of Protoplanetary nebula relate to TP-AGB? Equal or LAGB later than TP-AGB? ... said: Rursus (bork²) 14:30, 9 January 2009 (UTC)

There's a note at the end of the PPN article which says that they are defining the LAGB stage to be the point at which the AGB star ceases to be visible in the optical. Not many AGB people use that term (LAGB), but with that definition, the LAGB would be a subset of the TP-AGB, towards the end.Nucleardave (talk) 21:51, 7 December 2010 (UTC)

Evolutionary track image

Not sure if this is the right page for discussion, but this is one of only a couple pages that use the image http://en.wikipedia.org/wiki/File:Stellar_evolutionary_tracks-en.svg . It only shows four tracks, which could be a LOT more informative--The tracks are all extremely different, and it's hard to tell what's going on in between them! For example, what will become of a 5 Solar mass star? Will a 1 Solar mass star make the same jog to the left as a 2 Solar mass star? I've been building an understanding from this [2] page and its image, but that deals with stars entering the main sequence, not leaving it... however, even a few more 'topographical' lines make it a lot clearer.

Can someone give an idea of where the lines for 30, 5 and 1 solar mass stars would go? Even if you can't update the image, I would like to know what they would look like. Thanks! --Sowelu (talk) 09:55, 21 October 2009 (UTC)

S-stars and carbon stars

Should this article mention how do asymptotic giant branch stars relate to S-type stars and carbon stars? Should this also discuss if every AGB star turns into S-type star and a carbon star before it turns into a preplanetary nebula? --Artman40 (talk) 05:21, 24 June 2014 (UTC)

They're mentioned. If you can add more information or explain it more clearly, then go ahead. Note that there is a fairly lengthy article about Carbon Stars and a stub about S-type stars, so detailed information about these stars should probably go there, with this article restricted to describing how AGB stars are related to those and then linking. Lithopsian (talk) 15:45, 24 June 2014 (UTC)

Assessment comment

The comment(s) below were originally left at Talk:Asymptotic giant branch/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.

A diagram would help. I am thinking of a HRD, with a line showing the Main Sequence, an outline showing the region where these stars originate, and a track, showing the evolution of these stars through the diagram. Possibly it should be a sequence of outlined regions, connected by arrows. The use of colour might also help the diagram.

Substituted at 18:08, 17 July 2016 (UTC)

During The Asymptotic Giant branch, Is the Sun larger than during its Previous red giant phase?

I've heard that the Sun will become larger on the Asymptotic Giant Branch than Its first red giant phase. Is this going to Happen?--THE COLOSSAL GALAXY NAMED IC1101 (talk) 06:50, 21 July 2020 (UTC)

AGB stars are generally both more luminous and cooler than RGB stars, hence larger. The sun is expected to become an AGB star at some point. Many of the more popular writing about "the sun as a red giant" doesn't distinguish between the two stages and may well be referring to the AGB. Read carefully between the lines, or refer to sources that actually distinguish the two phases. Lithopsian (talk) 14:17, 21 July 2020 (UTC)

The luminosity is thousands of times itself

"The luminosity of the shell flash peaks at thousands of times the total luminosity of the star"

Instead of "total" would it be clearer to say "main branch" or "average"? Hcobb (talk) 16:36, 31 January 2021 (UTC)

It is neither of those things. Or both if you like, but hardly relevant. What it is, and what it is trying to say, is that the flash "luminosity" is thousands of times greater than the electromagnetic radiation being emitted from the surface of the star at the time of the flash, or for that matter somewhat before or after it. Luminosity is also a poor word since none of the energy is visible. Lithopsian (talk) 16:53, 31 January 2021 (UTC)