B Neutron Star Collisions: Creation of Heavy Elements and Their Fate

[tovisonnenberg]

When neutron stars collide, heavy elements, such as gold, are created. Are these elements ejected from the system to be found, say, here on earth? Or do they fall back into the newly created black hole?

 

[mathman]

Short answer: both.

 

[phyzguy]

If they all fell back into the newly created black hole, then these events could not contribute to the concentration of heavy elements in stars and planets. The answer is that a significant quantity of these heavy elements get ejected from the binary neutron star system and get incorporated into the InterStellar Medium (ISM). The estimates from the recently detected neutron star merger GW170817 are that about 0.01 solar masses of heavy elements were ejected. When stars and planets later form from this ISM, these heavy elements are incorporated into these new stars and planets.

 

[unusually_wrong]

On a side note, I read that many heavy elements are created when a star goes supernova. Those elements are also ejected from the star.