Stellar mass limits for Neutron Star and Black Holes 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.


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?

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.
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?
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.