Talk:Compact object

redirect

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)

Somebody did far ago from 20:25, 10 May 2009 (UTC). ... said: Rursus (bork²) 20:25, 10 May 2009 (UTC)

Forever?

"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)

Terrible

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

First Paragraph

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)

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)

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)

The star attempts to cool itself?

"In an attempt to cool itself, the star radiates energy in the form of surface luminosity." Should this be described so animistically? This radiation of energy is just a basic consequence of natural laws/physics. FirstMatter (talk) 23:16, 30 January 2015 (UTC)

Hello. I have rewritten the paragraph. It was badly explained altogether and the stellar life cycle is explained in great detail on linked wikipedia articles.

What you call "animistic" is often used when discussing and describing stars, even in pure scientific terms. Actually words like "death", "life", "attempt" etc. are used extensively in the natural sciences. Mostly for pedagogical reasons, but also because the natural sciences does not distinguish as rigidly between animals (including the human) and objects, as some people would like to believe. These distinctions are to a large degree of religious and cultural origin. What you object against is probably (?) that words like "attempt" implies some kind of conscience, and that inanimate objects (whatever that is) does not have a conscience? Well everybody and everything is guided by forces and the laws of nature and when inanimate objects "attempt" something, it just means that this is their reaction to these laws and forces. I agree that "animistic" words should be limited and used with caution when discussing science, but they certainly have their place too. A better description in this particular situation would simply be "In order to cool itself, ...". RhinoMind (talk) 12:19, 31 January 2015 (UTC)

Creation vs Formation

@JorisvS: changed the words "creation" to "formation" some time ago throughout the article and I was wondering why? Is there any reasonable explanation for this change?

As I grasp these two terms (as an astrophysicist, but not a native speaker of English), a formation is exactly that: something that is "formed" or rearranged so to speak. I believe the correct terms to be used here is "creation", simply because something new is created. It is not just a forming or rearranging of something that already existed prior to processes discussed. It is something new. A creation. I am looking forward to some kind of reasonable explanation. Cheers. RhinoMind (talk) 01:14, 24 March 2016 (UTC)

Creation is an act by a someone/something to make something else, to be given a shape, to be made to be. To form (the intransitive form)/formation means 'taking shape', 'become to be', which is the correct meaning here. There is no entity that caused them to become what they are. Compare wikt:create and wikt:form#Verb #2. --JorisvS (talk) 19:31, 24 March 2016 (UTC)

@JorisvS: Oh, for some odd reason I didn't read nor respond to the post above. It is a long time ago now, and not an urgent issue in any way. However, I would like to challenge the understanding that creation needs an entity. For example, the entire universe has been created (not formed), and it didn't require an entity. RhinoMind (talk) 15:33, 25 May 2019 (UTC)

@RhinoMind: It is, as you say, a long time ago, and I think the likelihood of JorisvS ever seeing your latest message may be very low, because she or he virtually stopped editing in July 2016. After editing for many years at a rate of hundreds or thousands of edits per month, they abruptly stopped editing on 26 July 2016; so abruptly, in fact, that I might have thought they had died but for the fact that they came back and made just three edits, all within a period of less than 10 minutes, in June 2018. However, if it's of any interest to you, here are my thoughts on the matter. I am a native speaker of English, and in my experience JorisvS is right: I don't remember ever having come across the words "create" and "creation" used except in the sense of creation by someone or something. Also, your statement that "the entire universe has been created" is highly contentious: there are people who very strongly hold the view that the universe was created, and others who just as strongly hold the view that it wasn't, so simply stating that it was created, as though that were an undisputed objective fact, is a mistake. JamesBWatson (talk) 20:11, 25 May 2019 (UTC)

Hi, and thanks for the details. I didn't look all that up, and I think you might be right in your ideas.

About the word "creation": I think this is purely a cultural issue. Maybe even a religious one, which could easily be the same thing on a deeper level. In scientific circles, it is not uncommon to talk about the "birth of the Universe" even, yet no one would in their wildest dreams believe that a proper birth from some entity took place. Just as other fields, science is full of metaphors. Mainly because it is unavoidable when you use everyday language to mediate insight and knowledge. Language is always seeped in culture, religion and human history, it is unavoidable, yet that does not imply that everything and every word is to be understood in a certain and very specific way, be taken literally, or have the same meaning, in all contexts. I think most people understand that about the use of words and language? If not, I really feel sad for them.

Other well-known example are the "creation of life" or the "creation of the chemical elements". At some point in the history of the universe, life and the elements must have been created somehow and somewhere, yet that does not imply there was a responsible entity doing it.

Perhaps creationists read Wikipedia articles once in a while, maybe even about scientific subjects? Yet, I can hardly believe that using the descriptive word "create" could be misunderstood as some kind of entity creating stuff. People are welcome to think that, ordinary religious people too, science does not exclude such a belief, but it is all their own reading and interpretation of that word.

I think this is an interesting discussion all together, it certainly reach out to interesting fields and subjects about preconceived world views, cultural assumptions, and reality versus the human mind. I am just not sure though, that we could end the discussion in any meaningful and conclusive way.

Btw. The word "formed" is basically wrong. I explained the reason in my former post. RhinoMind (talk) 23:03, 25 May 2019 (UTC)

New name with working verb needed to distinguish between collapsing stars

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)BG

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)

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)

OK, then I will focus this issue on the "Collapsar" stub. 72.69.60.186 (talk) 00:44, 25 June 2016 (UTC)BG

Planetary mass stellar remnants

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)

Very massive

IMHO anything near the Chandrasekhar limit is not “very massive” in astrophysical context. There was some poorly considered passage in the introduction (which I removed boldly), but currently defended by a user not usually seen anywhere near astrophysics, except for stalking me (Incnis Mrsi). I 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)

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)

And more. The user who stalked me argues that “[a] star with just a small radius is just a small star” – see his edit summary. Of which small radii does he speak? How many times a typical red dwarf is larger than the largest white dwarf possible? Neutron stars are yet much smaller. Incnis Mrsi (talk) 16:49, 24 May 2019 (UTC)

• For convenience of anyone else who reads this section, the words "a user" in Incnis Mrsi's post above link to my user page.
• This is the page for discussing content of the article Compact star. It is neither the place for criticisms of other editors, nor the place for defense against such criticisms, so I shall stick to commenting on the issues regarding content of the article.
• The article listed categories of compact stars, and then went on to say "The term compact star is often used when the exact nature of the star is not known, but evidence suggests that it is very massive and has a small radius, thus implying one of the above-mentioned categories". You removed the expression "very massive", leaving the statement that any star with a small radius is likely to be called "compact". Rightly or wrongly, I thought that was a mistake, as I thought that it was only a star for which the radius is small in relation to the mass that is likely to be so called. I don't defend the wording "very massive and has a small radius", and I am sure that it could be better phrased, but I thought that just saying "small radius" without any mention of the mass was a mistake. I am perfectly willing to acknowledge that I may be wrong, that is to say the expression "compact star" may indeed be commonly used to refer to just any star with a small radius, no matter how low its mass may be; if so then by all means please provide a source confirming that it is. JamesBWatson (talk) 10:42, 25 May 2019 (UTC)

  Will JamesBWatson dispute that a white dwarf is not “very massive”? In the context—namely, astrophysics—appropriate for this article. Incnis Mrsi (talk) 10:49, 25 May 2019 (UTC)

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)

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)

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)

My knowledge doesn’t really reach an expert level. I 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)

Compact objects

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:

• [1]
• [2]
• [3]
• [4]
• [5]
• [6]

jps (talk) 20:58, 13 December 2023 (UTC)