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From the article: "Black holes, if you recall, are created when stars run out of fuel and die. In dying, they collapse into a much smaller mass with such eno
by AndrewHampton 15y ago
From the article:
"Black holes, if you recall, are created when stars run out of fuel and die. In dying, they collapse into a much smaller mass with such enormous gravity that it sucks in just about anything that comes light years near it."
I may be wrong, but doesn't the mass of the black hole roughly equal the mass of the star? I know some is lost during the explosion, but I thought the mass stayed roughly the same and just the volume significantly decreased.
- suprgeek 15y agoEssentially correct. The dying star does not collapse into a "smaller mass", the amount of mass stays the same (difference between the stars original mass and the cast off from the preceding supernova). It just gets crushed into a very tiny volume.
- lutorm 15y agoWell, not really. The mass of the black hole created equals the amount of mass that falls into it, of course, and to first order the mass of the BH will be equal the mass of the iron core of the star. That mass is however quite a bit smaller than the mass of the star, and very much smaller than the initial mass of the star. (A star has to start out with a mass > 8* the mass of the Sun to go supernova, and that will only guarantee that it forms a neutron star whose mass will be of order 1 Solar mass. The rest is lost first during the life of the star, as massive stars are so luminous they drive their own matter off from the surface, and then ejected in the explosion itself. Edit: The article has a number off, as it states that the black hole has a mass of 15 Solar masses and that the companion is 19 times larger. The original article says the companion is 19 Solar masses, which makes more sense.
- maaku 15y agoI know some is lost during the explosion, but I thought the mass stayed roughly the same and just the volume significantly decreased. The first part answers the second. A lot is lost in the explosion.
- sesqu 15y agoI believe the author means to use "small" as a descriptor of volume rather than of measure, and "mass" as a generic noun rather than a quantity. In fact, interpreting "a small mass" as "something light" would be incorrect without a constant density. It's not a great sentence, because it's easy to get confused like that, but it is correct.