Talk:Red giant

Table

It would be useful to show a table of how many red giants exist in total right now; at the least denoting the date and a rough number. Right now visitors can not quickly obtain this information - are there 100 red giants? 1000? 100000? Nobody knows right now from this wikipedia article alone. That should be changed in the long run; a rough estimate is fine. 2A02:8388:1604:CA80:0:0:0:1 (talk) 16:43, 26 May 2019 (UTC)

How should we explain why a red giant expands?

Currently it is stated fairly baldly that it does, but some explanation would be better. Unfortunately, a detailed water-tight explanation is probably too complex to be understood by most readers. Can we fudge it with some sort of shell-mirroring explanation? The mirroring is true enough; the full details of why are again quite complex, but with a bit of hand-waving it should be possible to come up with something that will convince most people. Once the mirror principle is accepted, all sorts of aspects of red giant evolution become very easy to explain. Or do we head off down the convection path? That isn't really the reason why red giants expand in the first place, although it explains why they expand more after they initially become red giants. Most people would probably just buy that it was all down to convection, though. Lithopsian (talk) 19:06, 6 June 2019 (UTC)

Closest red giant?

Some sources name Gacrux as the closest R.G. to the Sun, but Arcturus is actually closer. What's the right answer? -- A man without a country (talk) 17:08, 17 July 2019 (UTC)

The article explains it. γ Crucis is the closest class M giant, but K0 Arcturus is closer. Lithopsian (talk) 17:32, 17 July 2019 (UTC)

Thanks. I copied that into preamble. I think preamble also has to answer such questions as:

• What exactly causes RGs to be luminous?
• What is current share of RGs in the Milky Way?
• What is the share of stars which will become RGs in the Milky Way?
• What is the fate of RG stars?

A man without a country (talk) 15:51, 23 July 2019 (UTC)

The lead doesn't have to contain the entire article ;) Most of this information is already in the article. Red giants are luminous for a variety of reasons, partly dependant on your viewpoint, but basically their interiors are hotter and hence fusing at a higher rate than main sequence stars of the same mass (on average, there are exceptions). The fraction of stars that are red giants varies depending on which set of stars you look at; for example, young clusters will contain no red giants while they are (relatively) very common in old globular clusters where young stars are no longer being born. In the solar neighbourhood, around half of one percent of stars are giants, most of those of spectral type K. The only stars that do not become red giants are the tiny number of the most massive, and the least massive red dwarfs, although red dwarfs do make up about three quarters of all stars. Exact statistics depend on who you ask. The evolution of red giants is explained in the article; the simple answer is that in almost all cases they become white dwarfs, but the term red giant covers stars in several different evolutionary phases not all of which immediately progress to a white dwarf. Lithopsian (talk) 19:48, 23 July 2019 (UTC)

Well, there are rules on WP leads. Lead should introduce to subject and summarize the article. And these questions are not from my sole curiosity: they are from lead section in White dwarf, which is marked as good article. -- A man without a country (talk) 20:38, 23 July 2019 (UTC)

I suggest expanding the body first, referenced with reliable sources. Then you can try for a concise lead that summarises the important points. Just adding factoids to the lead will always make a mess. The comparison to white dwarf is apt, since red giants are arguably just as notable. That article is nearly five times as long, and that completeness is one of the reasons it was promoted to FA. Things have slipped a little since, but it is still a decent article. One complication here is that red giant covers several different types of star that are fully discussed in other articles. The new lead makes this a little clearer than it was, but it should still be explained properly in the body, probably with explicit sections and {{main article}} links. Lithopsian (talk) 19:51, 24 July 2019 (UTC)

The Sun as a Red Giant

In the section that talks about the Sun too eventually becoming a red giant, why isn't the possibility of the Sun swallowing up the Earth discussed in more detail, as well as the fact that all life on Earth will probably end long before the Sun even becomes a red giant? The possibility of whether if the Sun will actually indeed swallow up the Earth as a red giant is still an open question even today, although it's more likely that it actually will. — Preceding unsigned comment added by 23.28.197.157 (talk) 12:41, 10 April 2021 (UTC) What about the fact that Titan will probably become habitable as a result of the Sun becoming a red giant?

These things are, or could be, covered in a separate article. The link is right there in the article. This article is about red giants, not about the Sun. Lithopsian (talk) 19:49, 12 April 2021 (UTC)