Chances of a collision

[TnKicker]

Got a question.

When galaxies collide, what would be the probability of two stars collideing with each and other (mathematically speaking) and would't some of the smaller outer-stars and planets get slingshotted out of the galaxy orbit with strong enought gravity?

[symesie04]

Not sure what the actual statistics are but the chance of any collision is incredibly small. However its not pretty either way.  Both stars and planets are ripped from their neighbourhood and can be slung either inwards or outwards of the galaxy. Inward could result in being slung into areas rich in very radioactive stars, gamma rays and the like so not good for any life. Outwards would be into sparsely populated and largely cold areas of the galaxy so not good for life or even being slung out of the galaxy itself. Then you have the fact that much of the nebulous gas in the galaxies will become superheated and ionised which would look real pretty but wont do much for global warming.

[andrew s]

I have never seen a detailed calculation but I have seen it stated that a direct collision is very unlikely given the space between stars. However, tidal disruption would be considerable with some bodies being ejected completely. What happens depends a lot on the relative size of the galaxies.

Regards Andrew

[TnKicker]

54 minutes ago, symesie04 said:

Not sure what the actual statistics are but the chance of any collision is incredibly small. However its not pretty either way.  Both stars and planets are ripped from their neighbourhood and can be slung either inwards or outwards of the galaxy. Inward could result in being slung into areas rich in very radioactive stars, gamma rays and the like so not good for any life. Outwards would be into sparsely populated and largely cold areas of the galaxy so not good for life or even being slung out of the galaxy itself. Then you have the fact that much of the nebulous gas in the galaxies will become superheated and ionised which would look real pretty but wont do much for global warming.

It would be chaos truly, but the lightshow we would fitness could be impressive, if someting hasn't wiped us out before that. So I shouldn't look forward for the Andromeda collision with milky way in 3.5b years?   

[TnKicker]

1 hour ago, andrew s said:

I have never seen a detailed calculation but I have seen it stated that a direct collision is very unlikely given the space between stars. However, tidal disruption would be considerable with some bodies being ejected completely. What happens depends a lot on the relative size of the galaxies.

Regards Andrew

It would be pretty difficult to pinpoint the probablity of collideing stars I'm guessing, the amount of variables for that is just too high.

[Stub Mandrel]

The forthcoming gravity wave announcement got me reading around the subject. Apparently in a sphere 1000 LY around earth about ten pairs of neutron stars will spiral into each other every year!

 

I may have got this wrong.

[CraigT82]

32 minutes ago, Stub Mandrel said:

The forthcoming gravity wave announcement got me reading around the subject. Apparently in a sphere 1000 LY around earth about ten pairs of neutron stars will spiral into each other every year!

 

I may have got this wrong.

I've also done a little reading around the gravity wave detection. The interferometer they're using can detect changes in the length of a 4km vacuum tube to 1/10,000th the width of a proton. 

A PROTON!!!

 

p.s. Sorry to the OP for replying with a comment completely unrelated to this subject! 

[TnKicker]

2 hours ago, Stub Mandrel said:

The forthcoming gravity wave announcement got me reading around the subject. Apparently in a sphere 1000 LY around earth about ten pairs of neutron stars will spiral into each other every year!

 

I may have got this wrong.

Should do some reading on this as well, sounds really interesting.

[symesie04]

15 hours ago, Stub Mandrel said:

The forthcoming gravity wave announcement got me reading around the subject. Apparently in a sphere 1000 LY around earth about ten pairs of neutron stars will spiral into each other every year!

 

I may have got this wrong.

I understand that it is thought there are around 100 million neutron stars in our Galaxy. But given our galaxy is 100,000 LY in all directions 10 pairs in a 1000LY area every year does sound a bit high. Given many of them would of been formed from the deaths of third and second population stars and therefore been in existence for billions of years that number would suggest a massive mortality rate surely? Not saying its wrong just seems very high.