Black hole: An artist's drawing shows a large stellar-mass black hole pulling gas away from a companion star.Courtesy NASA E/PO, Sonoma State University, Aurore SimonnetThis, apparently.

Awesome.

More cool black hole information can be found here.

From the above site I learned that our own sun can never aspire to be a black hole.

The sun does not have enough mass to collapse into a black hole. In billions of years, when the sun is at the end of its life, it will become a red giant star. Then, when it has used the last of its fuel, it will throw off its outer layers and turn into a glowing ring of gas called a planetary nebula. Finally, all that will be left of the sun is a cooling white dwarf star.