Are blackholes formed in other ways besides supernovas?

[mdmaaz]

In science books I always have read that supper massive black holes explode in a supernova once they run out of fuel. After that the core of the star collapses and forms a black hole. But are there other ways in which black holes are formed in nature, besides the the core of a big star collapsing after a supernova?

 

[twofish-quant]

In science books I always have read that supper massive black holes explode in a supernova once they run out of fuel. After that the core of the star collapses and forms a black hole. But are there other ways in which black holes are formed in nature, besides the the core of a big star collapsing after a supernova?

There are monster black holes in the middle of most galaxies which seemed to have formed directly with gathering lots of gas and dust.

Also, we aren't sure about the details of the supernova/black hole relationship. The consensus seems to be that if you have a big enough star, it will go directly to a black hole without a supernova. However, where that boundary is, and if you can get a star go boom and then form a black hole is quite unclear.

 

[Nik_2213]

IIRC, if two neutron stars merge, the sum could be enough for a black hole to form.

 

[Drakkith]

Accretion onto a white dwarf of neutron star can cause it to gain enough mass to collapse into a black hole. (Though the white dwarf would first collapse into a neutron star)

 

[aurorasky]

Also, primordial black holes, formed in the early stage of the history of the universe, might exist. Primordial black holes are not the result of the gravitational collapse of a pre-existing massive star, but were mainly created in the extreme conditions after the Big Bang. They might be of any size and some might be detected thanks to their Hawking radiation emission. See here http://en.wikipedia.org/wiki/Primordial_black_hole.

 

[phinds]

In science books I always have read that supper massive black holes explode in a supernova once they run out of fuel. After that the core of the star collapses and forms a black hole. But are there other ways in which black holes are formed in nature, besides the the core of a big star collapsing after a supernova?

No, you have the first part of that statement backwards ... black holes don't explode in a supernova, STARS explode in a nova or supernova and the remnant of a supernova explosion can be (may always be, I'm not sure) a black hole. This IS what you're saying in the second part of your statement.

 

[ibysaiyan]

Accretion induced collapse is another hypothesis. Where a binary system made of two w.d(oxygen-magnesium) results a black hole.Essentially one of them goes onto become a red giant and other sucks in/accretes the less dense gases towards it.This drives further gravitational collapse which in a chain of events forms a neutron star.Once the Chandrasekhar limit is surpassed you end up with B.H however I have also read that a collapsed driven type 1A supernovae is also formed at that instant.
Other than that your usual transition of a B.H is by type II supernovae and ones mentioned by posters(above).
-ibysaiyan