How heavy do the star cause black hole?

Answer 1

When a stellar remnant is over about 3 to 4 times the mass of the sun (see Tolman-Oppenheimer-Volkoff limit) it is estimated to have insufficient outward pressure to resist gravitational collapse into a black hole. Note that larger stars would often explode into a supernova or become a planetary nebula, losing most of their mass this way first - perhaps over 75 percent - and thus the original star's mass needed to have a remnant heavy enough to collapse in a black hole would be much heavier than 3 times solar mass.

Answer 2

When a massive star collapses to form a black hole, its mass is typically several times the mass of our Sun. This critical mass is known as the star's "Schwarzschild radius," or the point at which gravitational forces overcome all other forces. The exact value of this mass depends on various factors, such as the star's initial mass and density.