Question: How big does a star have to be to become a black hole?

Hazel Gibson answered on 16 Mar 2018:

To become a black hole a star needs to be much much bigger than our sun – more than 24 times bigger in fact. When these stars become black holes scientists have a brilliant name for it: a ‘massive fail’ (haha!). This process of a huge star collapsing into a black hole was probably observed last year by NASA, when star N6946-BH1 disappeared and -probably- became a black hole! If you want to read more about this, check this link: https://www.nasa.gov/feature/goddard/2017/collapsing-star-gives-birth-to-a-black-hole