Stellar Grooming?

Question

Cygnus X-1 (the black hole) is known to have a blue giant in its orbit that will likely live its full life-span there, only a small amount of surface gas being drawn into the event horizon at each close point in its orbit.

Could this "grooming" by the black hole, removing the weight of converted heilium, actually extend its life by relieaving pressure on the star's core?

Answer 1

Well, the helium is all accumulating in the core where the fusion takes place. In most starts there is little or no convection between the core an the outer envelope.

Lower mass stars do fuse more slowly and live longer. Indeed, by losing mass, Cygnus' X-1 companion will have a longer lifetime than it would otherwise.

If you read about interacting binaries you will learn more about this phenomenon. Note that for a star to have filled its Roche lobe and start losing mass, it nearly always already has to be off the main sequence (and starting to puff up) and closing in on the end of its life, though one can imagine a circumstance where a compact companion has come closer to the surviving star and begins stripping matter from it while it is still on the main sequence.

Try looking up "blue stragglers" and "cataclysimic binaries" for more information on this.

Answer 2

A star undergoes nuclear fussion

Nuclear fusion is the conversion of hydrogen into helium.

2H1+3H1->4He2+1n0+energy

The star will continue to radiate energy until all hydrogen has been used it. It will then continue nuclear fusion with helium, to create lithium until all the way to iron. After iron the process will take in heat and so the star will start to die.

If this "grooming" removes converted helium, then there will be less helium for the star to convert to lithium and so on.

So i would have thought the life of the star would decrease. But relieaving pressure could increases its life and so a 2 way effect happens.

I would have thought having less reactants in nuclear fussion would outway the relief

Answer 3

Interesting thought. If X-1 took away a significant portion of the star's mass I would say yes. If it's a fraction of a percent there will probably be no significant change in its evolution.