Black Hole Identified #1

Under ideal, non-rotating conditions, a star only slightly more massive than our own Sun can theoretically collapse into a black hole (see Chandrasekhar Limit), so that it doesn't take a "supermassive star" to "die" and form a black hole.

Black holes become supermassive because they keep on eating long after they're formed.

Secondly, we shouldn't speak of black holes as "dead stars"! The physics of black holes are so radically and dramatically different from any stars, dead or alive, that it's best to say that large black holes are usually the result of a gravitational collapse of a star. Lots of stars have other kinds of interesting deaths without turning into a black hole. Our sun will expire, become a red giant, and then shrink into a dwarf star, but so? And other black holes aren't necessarily the result of stars dying. For example, the LHC at Cern is believed to be producing microscopic black holes. No stars dying there!

It should be massive instead of giant. The red giants are not massive.