Expert: Philip A. Stahl - 2/12/2008

Question
I was wondering what would happen to a multi-star system if one star went supernova or for some reason the gravity well collapsed.  Any help you could give me would be greatly appreciated and if you could recommend any literature on the subject of multi-star systems it would help.

Answer
Hello,

Assuming some binary star system, a supernova would herald some form of immensely dense collapsar - neutron star or black hole. This would mean (more than likely) an x-ray binary, with the outer gaseous envelope of the normal star being pulled into the dense companion. Of course, the magnitude of the effects would depend on the original proximity of the two stars.

R.W. Hildtich, in his excellent book, 'An Introduction to Close Binary Systems' (2001, Cambridge Univ. Press) also notes (pp.168-69) that it is feasible for a supernova "event" to cause a binary star orbit to become more eccentric or "even disrupt the binary completely".

He then goes into the specific conditions that would allow this, the primary one being that the companion star doesn't accrete any significant amount of the material ejected. (In the supernova)

Rather the total energy available (e.g. E = -G m1 m2/ 2a, where a is the semi-major axis; m1, m2 the respective masses) goes almost entirely into altering the relative dimensions of the original orbit.

As noted above, Hilditch's book is perhaps the best to get, because it not only provides outcomes for differing conditions, but shows quantitatively what conditions must be met.