Talk:Compact object

message: Can someone redirect "Stellar Remnant" to this article.  I do not know how to do it myself nor do I have time today to learn,--Dr.Worm 00:53, 12 May 2006 (UTC)
replies: text: Somebody did far ago from 20:25, 10 May 2009 (UTC)
thread_title: redirect

message: "Compact stars last forever" announces one heading boldly. Sure? Really? AFAIK black holes are believed to evaporate in the end. And beside that: this is a boring encyclopedia where bold newspaper headings aren't appropriate. A neutral heading such as "lifetimes" would be more appropriate. ... said: Rursus (bork²) 20:24, 10 May 2009 (UTC)
thread_title: Forever?

message: This is an article of particularly poor quality. Someone please help... 206.213.251.31 (talk) 14:41, 10 May 2010 (UTC)
thread_title: Terrible

message: I came here looking to learn something; that is, I am NOT an expert in the field and don't feel comfortable changing stuff here.  Still, even to this non-expert, the line in the first paragraph "These objects are all small for their mass." seems completely the opposite of what is intended, especially when it is followed by "... it is very massive and has a small radius".  Would somebody who DOES know something make just the first paragraph make sense?
Chopbox (talk) 00:56, 15 December 2013 (UTC)
replies: text: I'm no expert either, but I think it's OK. Perhaps have a look at the article on mass?  Rothorpe (talk) 01:32, 15 December 2013 (UTC)
replies: text: Small by volume but with a high mass. "Small" normally refers to volume, not mass, I think, but I said volume explicitly in the sentence which confused you. —Alex (ASHill | talk | contribs) 21:09, 16 December 2013 (UTC)
thread_title: First Paragraph

message: In astronomy, the term compact star (or compact object) is used to refer collectively to white dwarfs, neutron stars, and black holes. The term "collapsar" is also used to describe these 3 stars. For starts my problem with this is a white dwarf is way different than a neutron star or black hole, the densities are way over a million different. 
Why not use the term "collapsar" with an acting verb to describe what collapses in a star smaller than about 2.0 Schwarzschild radius? Lets consider what happens if an attempt is made to compress a star of 2.0 Schwarzschild radius down to 1.0 Schwarzschild radius. Assuming the star is made of protons, neutrons, and electrons, this should be reflected in the name for different types of collapse (unless all types of particles collapse at the same instant).
Consider: (1) A "proton collapsar" (2) A "neutron collapsar" (3) An "electron collapsar".
(3) sounds like baloney. As for (2) a neutron is just a proton and an electron so this process is the same as (1). When you compress a star enough at somewhere below about  2.0 Schwarzschild radius, you get proton collapse. Thats what should be analyzed. "Proton collapsar" would be a good name to describe this family of stars. It does not include white dwarfs. 151.202.5.131 (talk) 15:12, 21 June 2016 (UTC)
replies: text: Unfortunately any changes have to be made on the basis of reliable sources. Unless you can provide them no changes can be made. --Jules (Mrjulesd) 16:17, 21 June 2016 (UTC)

text: Hi. There are several problems with this post. 1 Wikipedia is not the place to discuss how astrophysicists should name objects. We only present information that has already been established by them. 2 To use an active verb, limits the usefulness of the word. Compact objects can also be created without a prior collapse. They can be relics from the early universe for one thing. 3 I can see that your understanding of the collapsing process of stars is insufficient. I would advice you to study more about what a Schwarzschild radius is. It is a distance that is innately linked to and determined by an objects mass and it can not be changed. Only if you add or remove mass will it change accordingly. Physical processes like compression will not change an objects SR. RhinoMind (talk) 00:21, 23 June 2016 (UTC)
thread_title:  New name with working verb needed to distinguish between collapsing stars 

message: Would stellar remnants which are composed of mostly carbon (diamond planet) i.e. red giants which have been stripped of their outer shells by a closeby pulsar or similar, belong into this class?
(Stellar remnant points here, so there should be some notion of it.)
They're not exactly stars any more, but very compact and consisting of rather exotic matter. --129.13.72.198 (talk) 12:38, 3 February 2017 (UTC)
thread_title:  Planetary mass stellar remnants 

message: IMHO anything near the Chandrasekhar limit is not “very massive” in astrophysical context. There was some poorly considered passage in the introduction (which  removed boldly), but currently  by a user not usually seen anywhere near astrophysics, except for stalking me (Incnis Mrsi).  don’t think that the introduction should refer to mass at all if such lightweight objects as white dwarfs are explicitly counted among compact objects. Incnis Mrsi (talk) 16:35, 24 May 2019 (UTC)
replies: text: to values of the mass of an object – with such epithets as “small/low”, “great/high”, or “very high”. Incnis Mrsi (talk) 09:23, 25 May 2019 (UTC)
replies: text: If you carefully re-read what I wrote above, you will see that I have not suggested that there are no compact stars that are not very massive; I have merely questioned whether the term is commonly applied to all stars with a small radius. JamesBWatson (talk) 11:07, 25 May 2019 (UTC)
replies: text:  The terminology is confused. In which sense is a stellar-mass black hole a star? It was a star somewhere in the past, theoretically near the event horizon but practically nothing of a star is in any way detectable except for its gravity, angular momentum, or electrostatic field. But indeed some of them are referred to as stars. Every object of stellar mass or heavier having the diameter smaller than ∼100,000 km is a compact star or a black hole. Why “or”? Because heavier holes—namely, intermediate—are not classified with stars. And, of course, there are small objects which are less massive: brown dwarfs and planemo. Incnis Mrsi (talk) 12:04, 25 May 2019 (UTC)
replies: text:  OK, that's clearer, thanks. With a specific statement as to what range of sizes we are talking about, it makes sense, and it seems that with that understanding all stars with a small enough diameter are indeed compact stars. It may well be that the editor who put the words "very massive" in meant something like "massive enough to be regarded as a star", but it is more likely to be read as meaning "very massive in comparison to other stars", so "of stellar mass or heavier" expresses it better. However, do you think it would be helpful to indicate more precisely what "a small radius" means, either by giving your criterion of "diameter smaller than ∼100,000 km" or in some other way? JamesBWatson (talk) 14:24, 25 May 2019 (UTC)
replies: text:  My knowledge doesn’t really reach an expert level.  know that “live” (that is, fusing) stars are much larger than white dwarfs because of difference in temperature and chemical composition. It would be reasonable to say: anything of stellar mass, but smaller than a “live” red dwarf could be. Incnis Mrsi (talk) 15:33, 25 May 2019 (UTC)
thread_title:  Very massive 

message: The more common term is compact object, and so I've migrated the page over to the new title. I am a little concerned by the list of "sources" which seem to have looked for fairly idiosyncratic uses of "compact star" in the literature. These sources aren't bad, but they don't seem to capture the full sense of the topic. Here are some standard indicators for the "compact object" term (and likely useful sources for the article:
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jps (talk) 20:58, 13 December 2023 (UTC)
thread_title:  Compact objects