View Full Version : collisions between stars

2003-Apr-29, 04:26 PM
The thread on type I supernovae got me wondering.

What would happen if, say, a neutron star were to collide (at high speed so that it doesn't have time to suck all the gas off the star being hit beforehand) with a star like, say, the sun. I realize that if it happened to the sun, we wouldn't be around to enjoy the show. But what would happen?

Ditto if the neutron star were to collide with, say, a white dwarf and if it were to collide with a super massive star like Betelgeuse or the Pistol Star?

Speaking of Betelgeuse, it's relatively close as stars go, only a few hundred light years away. Supposing it were to go supernova, what sorts of ill effects, if any, would we suffer? I know that some nebulae are thousands of light years in size and we're well within that range.

2003-Apr-29, 05:07 PM
For starters, it was once postulated that neutron star collisions with each other are causes of GRBs, but their locations failed to correlate with the galactic plane.

As for collisions with others stars, clearly a lot of radiation will be given off, probably at high frequency. Black holes may be formed.

2003-Apr-29, 05:09 PM
The speed, inner structure and impact angle of these two stars would change the ending result some. I don't know how much, though. Here is what I've read about two stars colliding with a modest speed:

Neutron star hitting our sun would create either a neutron star with a ring or a black hole. Neutron star hitting a white dwarf would end in a similar result.

When a supergiant is hit by a neutron star, the result is a white dwarf with either a black hole or a ringed neutron star.

The higher the speeds get, the harder it is to predict what will hapen. But it's always the more denser star which takes less damage. For example, a white dwarf hitting our sun probably pierce through our sun mostly unharmed.

You might be interested in this link:

The Bad Astronomer answers pretty well to your question about the supernovae there.

2003-Apr-29, 05:47 PM
Awesome. Although the Stellar Database says that Betelgeuse is about 427 light years away, far less than the 1000+ that BA suggests in that link. Which to believe?

Also, I was curious not just about radiation but about the blast itself. Is it possible that the exanding gas cloud would reach the earth eventually? Would we even notice or would it be spread too thin by that point?

Kaptain K
2003-Apr-29, 06:09 PM
This was the cover story in the November 2002 issue of Scientific American.

JS Princeton
2003-Apr-29, 07:07 PM
A "collision" would probably not happen per se. Rather, the two might scatter off each other, or a capture process could occur whereby they entered into a binary system. Earlier this month someone had posted a great link to show what happened if rogue stars or planets entered the solar system. Direct collision with the parent star is just not something that is very common at all... and even if it does happen, the process is likely to be elastic and no coalescence will occur (though it would be particularly disruptive).