Our solar system's proximity to other ones

[jaketodd]

Is our solar system either closer to or farther from other solar systems in our galaxy compared with the average distance of one solar system to another?

Thanks,

Jake

 

[Tanelorn]

I also want ask what is the average distance between stars in the central hub of the galaxy which I presume is where the most ancient stars and maybe life forms exist..

 

[Vagn]

There shouldn't be any life forms in the central bulge of the galaxy as there are very little amounts of the heavy elements in the central bulge which are necessary to form planets and as far as we know, life.

The stars in the central bulge are much closer together than they are in the disc (where we are) and the spirals, so planets that have formed there could have had their orbits easily disrupted by a passing star, causing them to spiral into or away from the sun, so there would be very little chance of life survining, if it did manage to form in the first place.

The average distance between stars across the entire galaxy can be calculated by finding the stars per unit volume and cube rooting, which would give about 3.5-4.3 light years, however this would vary across the galaxy, it would be greater than this near the galaxy's edge and would fall as you move towards the central bulge. I can't find any figure at the moment though.

 

[DaleSwanson]

The Sun is about 2/3rds of the way towards the outer edge of our galaxy from the center. Stars are much closer together in the center, and much further apart at the edge. It's probably fair to say the Sun is in an area of the galaxy with typical stellar density.

Here is a rendition of our galaxy that shows the various areas and densities, as well as where the Sun is.
http://en.wikipedia.org/wiki/File:236084main_MilkyWay-full-annotated.jpg"

 

[Tanelorn]

I agree that the center of the galaxy would be extremely hostile to life but do you think this applies to the whole extent of the milky way central hub or perhaps say the inner 20%?

Where are the oldest stars in our galaxy, are they distributed evenly in proportion with all the other stars?

 

[NobodySpecial]

Where are the oldest stars in our galaxy, are they distributed evenly in proportion with all the other stars?

The oldest stars are in the halo - the outer lowest density part of the galaxy.

These are also the lowest metalicity stars so even if they did have planets (unlikely) they wouldn't be very interesting.

 

[Tanelorn]

So does this just leave the spiral arms where life as we know it could exist?

 

[NobodySpecial]

So does this just leave the spiral arms where life as we know it could exist?

Well we don't have a lot of evidence either way!
But it would seem that the arms are where long lived metal rich stars are likely to be found, so if you want a place just like Earth it's a good start.

 

[Tanelorn]

Does this mean that massive non spiral galaxies without arms eg. Elipticals would have problems supporting life either due to lack of metals or radiation? I believe that Elipticals were once spirals, but collided with other galaxies.

 

[NobodySpecial]

I think the jury is still out on exactly how spiral arms form - but no in this context I meant that in our galaxy the stars between the core (too short lived) and the halo (too metal poor) are where Earth like planets might exist. In the milky way there are spiral arms here but that doesn't necessarily mean that spiral arms are a requirement for metal rich stars.

There is (or was - I'm a bit out of data) a theory that the spiral arms form shock waves which bring gas and dust together and so increase the chance of star formation - I don't know if this is still current.