Does a star lose mass when it becomes a black hole?

Question

or does it stay the same?

Answer 1

Yes, it loses mass.

A black hole is the result of a star's death and collapse.  As it goes nova it explodes dumping a lot of its matter into space creating nebula from which new stars and planets will eventually form.

A star about 10-19 times the size of our star will die and collapse into a neutron star.  Smaller stars will collapse into a black hole.  Larger stars will continue the collapse from a neutron star and form a black hole.

It actually only takes the mass of a star 10 times the size of our own to form a black hole so that means in a nova roughly half the matter of the star is expelled into space.

According to Wikipedia:  http://en.wikipedia.org/wiki/Planetary_n...

"A planetary nebula is an emission nebula consisting of a glowing shell of gas and plasma formed by certain types of stars when they die. The name originates from a similarity in appearance to giant planets when viewed through a small optical telescope and is unrelated to planets of the solar system. They are a relatively short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years.

At the end of the star's life, during the red giant phase, the outer layers of the star are expelled via pulsations and strong stellar winds. Without these opaque layers, the remaining core of the star shines brightly and is very hot. The ultraviolet radiation emitted by this core ionises the ejected outer layers of the star which radiate as a planetary nebula."

According to Wikipedia:  http://en.wikipedia.org/wiki/Black_hole#...

"Note that this can be substantially less than the original star - remnants exceeding 5 solar masses are produced by stars which were over 20 solar masses before the collapse."

If the black hole formed from a supernova (http://en.wikipedia.org/wiki/Supernova) then even more matter will be expelled into space.  The larger the star the shorter and more violent its life so a black hole is more likely to form out of the remains of a supernova.

The point where a star can collapse into a black hole or not depends on the Chandrasekhar limit (http://en.wikipedia.org/wiki/Chandrasekh... for White Dwarfs and the Tolman-Oppenheimer-Volkoff Limit for Neutron Stars (http://en.wikipedia.org/wiki/Tolman-Oppe...  If the stellar mass exceeds that of the Tolman-Oppenheimer limit then it has no choice but to collapse into a black hole.

According to Wikipedia:  

"A black hole formed by the collapse of an individual star must have mass exceeding the Tolman-Oppenheimer-Volkoff limit. Theory predicts that because of mass loss during stellar evolution, a black hole formed from an isolated star of solar metallicity can have mass no more than approximately 10 solar masses."

Answer 2

Not all stars become black holes. It takes a radical event to form a black hole. Something like a super nova or two stars colliding.  

Answer 3

  If a black hole could exist it would be the result of a massive star going super nova and the remaing matter about 2 solar masses would collapse to a sphere of about 3 km in diameter.

  So yes the star would lose mass maybe more than 20 solar masses.

Answer 4

NO... black hole have infinite mass... because they suck in all matter with its infinite gravity field...

Answer 5

Since most black holes form from supernovae, the star will shed its outer layers in the process of "blowing up" so it will lose some of its mass. What collapses into the black hole is the core of the star itself, which will only collapse into a black hole if it is massive enough such that gravity is stronger than the outward pressure of the hot, compressed gas near its core.

So the star loses mass in the process of going supernova, but when the black hole itself is collapsing, the mass that was left over after the explosion is preserved in the new object that has warped space and time

Answer 6

Black holes do not exist, even in theory

http://www.sjcrothers.plasmaresources.co...