Do stars exist only in galaxies?

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Offline Refractor

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Do stars exist only in galaxies?
« on: 06/05/2010 14:30:02 »
Geoff asked the Naked Scientists:
   
Do all stars exist in galaxies or are there some loners out by themselves in the space in between?

Thanks for the newbielink:http://www.thenakedscientists.com/HTML/podcasts/ [nonactive].

What do you think?
« Last Edit: 06/05/2010 14:30:02 by _system »

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Offline LeeE

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Do stars exist only in galaxies?
« Reply #1 on: 06/05/2010 17:00:09 »
Stars can only form in galaxies but it is possible for a relatively small star to be ejected from its parent galaxy as a result of a close encounter with a much larger star in a slingshot maneuver.
...And its claws are as big as cups, and for some reason it's got a tremendous fear of stamps! And Mrs Doyle was telling me it's got magnets on its tail, so if you're made out of metal it can attach itself to you! And instead of a mouth it's got four arses!

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Offline Refractor

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Do stars exist only in galaxies?
« Reply #2 on: 09/05/2010 10:05:02 »
OK, so presumably they'd be not far from the galaxy of their birth.  I wonder if there are any known examples of stars out on their own, and how far out they might be.

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Offline GlentoranMark

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Do stars exist only in galaxies?
« Reply #3 on: 09/05/2010 11:06:36 »
I've never considered the question so thanks for asking.

I done a little googling and found this:

http://en.wikipedia.org/wiki/Category:Extragalactic_stars [nofollow]

I also notice that one of the shuttle missions was used to research such stars.

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Offline LeeE

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Do stars exist only in galaxies?
« Reply #4 on: 09/05/2010 14:09:49 »
I've never considered the question so thanks for asking.

I done a little googling and found this:

http://en.wikipedia.org/wiki/Category:Extragalactic_stars

I also notice that one of the shuttle missions was used to research such stars.

Actually, most of the stars in that list are only extra-galactic in the sense that they exist outside our galaxy; apart from HE 0437-5439 and PSR J0537-6910, they are all in the Large Magellanic Cloud (LMC).

Only the first star in that list, HE 0437-5439, is clearly outside any galaxy, having been ejected from the LMC.

It's less clear whether PSR J0537-6910 is actually outside the LMC or still within it.  Its Right ascension and Declination put it in the direction of the LMC but it seems to be 13,000 light years further away from us than the LMC itself.  However, the LMC is reckoned to be ~14,000 light years across, so if the same measuring datum are used for both the LMC and PSR J0537-6910 then PSR J0537-6910 may only be ~6,000 light years outside the LMC.

What I'm not sure about is whether the same datum do apply though.  It wouldn't surprise me to find that the distance between the LMC and our Milky Way galaxy is measured between the galactic centers, so while the center of the LMC may ~157,000 light years from the center of our Milky Way galaxy, the Earth is ~25,000 light years from the center of the Milky Way galaxy.  If then, the distance to PSR J0537-6910 is measured from the Earth, as seems likely to me, but the distance to the LMC is measured from the center of the Milky Way, PSR J0537-6910 could be well within the LMC.
...And its claws are as big as cups, and for some reason it's got a tremendous fear of stamps! And Mrs Doyle was telling me it's got magnets on its tail, so if you're made out of metal it can attach itself to you! And instead of a mouth it's got four arses!