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Don't hate on me if I am asking a very basic and straightforward thing. I have a few questions about black holes and neutron stars.

  1. What is the mass range (in terms of solar masses) for a main sequence star to end its life as . . .

    • A) a neutron star?
    • B) a black hole?
  2. Is it there a (practically observed or proven) possible method for a main sequence star to form a neutron star (or black hole) at the end of its life cycle without undergoing through the process of supernova?

    If yes, please explain or guide me some article on this matter.

  3. What is the mass range of a main sequence star to end up as a pair instability supernova?

    If the range of pair instability supernova overlaps with that of neutron star or black hole forming supernovae, how do we determine what type of end a star would have?

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A succinct summary of supernova types is given in the following image based on Heger et al. (2003):


Image courtesy of Wikipedia user Fulvio 314 under the Creative Commons Attribution-Share Alike 3.0 Unported license. The graph is based on the graph in Fig. 1 of the linked paper.

The pair instability realm is upwards of ~100 solar masses, though it is metallicity-dependent (Question 3). As Figure 1 (below) shows, neutron stars form in the mass range of >9 solar masses - again, this is metallicity-dependent (Question 1a). Starting at around 25 solar masses, black holes will form (Question 1b).

It is thought to be possible for a black hole to form without a supernova (see the section of the graph marked "direct black hole"). This has not been confirmed observationally, although there are some possibilities. I've written about this in more detail here.

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  • $\begingroup$ Extremely helpful answer (y). Just asking a couple more things here in comments. 1) what is the common name (not star code temperature category, but common name, as in red giant, orange dwarf, brown dwarf etc) of these stars? As in, what do we call a star which would undergo supernova to create a 1) neutron star 2) a black hole 3) a pair instability supernova. I do admit that your answer really answers all my basic questions, just asking you to go an extra mile if you please :) $\endgroup$ – Youstay Igo Apr 27 '16 at 16:29
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    $\begingroup$ I'll just add that the plots above show that there is indeed the possibility that a star might directly collapse to a black hole. It is labelled "direct black hole" in the second plot and is just marked as black in the first plot. Only the black holes by fallback are the result of a core-collapse supernova. A type Ia supernova is a thermonuclear detonation; nothing gets left behind. The recent GW discovery of merging 30 solar mass black holes may be the first evidence for direct collapse black holes, since fall back BHs are unlikely to be so massive. $\endgroup$ – Rob Jeffries Apr 27 '16 at 18:45
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    $\begingroup$ @YoustayIgo Supergiant and hypergiant are the commonly used term to denote these stars, as compared to main sequence dwarfs, like the Sun. $\endgroup$ – HDE 226868 Apr 27 '16 at 22:14
  • $\begingroup$ @HDE226868: Thanks. So there is no further precise term to differentiate, say 10x solar mass star from a 25x solar mass star? As in, is there any precise term to differentiate a start which would collapse to form a neutron star, from one that would be annihilated completely in a pair instability supernova? If there are no such elaborate common names, do these stars fall under different temperature categories (O B A F etc) then? $\endgroup$ – Youstay Igo Apr 28 '16 at 6:57
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    $\begingroup$ @YoustayIgo: I'm not aware of any precise terms such as you suggest. As for spectral type: all of these stars would start as main-sequence O or B stars (all the really massive ones would be O stars). But since spectral type depends on the surface temperature, individual stars may change spectral type during their evolution, so that when they explode, they might be O or B supergiants or red (K, M) supergiants. (Depending on things like metallicity, binary effects, etc.) $\endgroup$ – Peter Erwin Apr 28 '16 at 16:56

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