FINAL FATE OF A MASSIVE STAR

What would be the final endstate of a massive star, tens of times the mass of the Sun? This is one of the most important unresolved issues in astronomy and astrophysics today. Stars much more massive than Sun cannot settle to either white dwarf or neutron star final states, when they gravitationally collapse towards the end of their life-cycle on exhausting their internal nuclear fuel. Such stars must then undergo a continual collapse and shrink under the force of their own gravity. There are no balancing forces of nature which would resist the powerful inwards pull of gravity that collapses such a massive star. The problem of its final fate is then to be decided and resolved within the framework of Einstein's theory of gravity. This conundrum on the endstate of a massive star has key links to the early fundamental works on stellar structure by S Chandrasekhar, and it remains unsolved since the 1930s.

We shall discuss and review here the recent developments in the field. It turns out that depending on the initial data of the collapsing cloud, such as its density and pressure profiles and the velocities of collapsing shells of matter, the star could make either a black hole or create a visible super-ultra-dense region in the universe, called a naked singularity, which may have intriguing observational consequences.