by BDanielMayfield » Sun Oct 06, 2013 6:14 pm
Ann wrote:BDanielMayfield wrote:
Thanks Anthony. The range of ages of the stars inside these objects was something that hadn't occured to me. Pop I stars inside an object would mean that it wouldn't be a globular cluster, as their stars are all extremely old.
That is not actually true. If you check out
this topic, you can read about a Population I star that is only 190 light-years away from us. This star is extremely metal-poor, and astronomers consider it the oldest star they know. But this star is not located in a globular cluster. Although I haven't checked, I would guess that this star is a halo object, and that it is passing us by in its orbit around the center of the Milky Way.
It is true that stars in the bulge of a galaxy tend to be metal-rich even though they are old. Since they are metal-rich, they most certainly don't belong to Population I. They were born from gas that had been recycled through several generations of stars. But can we be sure that there are no Population stars in the bulges of galaxies? Normally we can't be sure of this at all.
This picture shows two globular clusters that are embedded in the bulge of the Milky Way. These globulars are just passing through, but they will likely lose some stars during their crossing of the bulge. Will the "lost stars" end up in orbits that really make them true members of the bulge? I think that is unlikely.
So it is an interesting question if there are any Population I stars in M60-UCD1 or in M32. Perhaps there aren't any. If Population I are either halo objects or members of globular clusters, then there may not be any such stars in a galaxy that has been whittled down to its bulge.
Ann
Ann wrote:Bystander wrote:
I think you have your populations confused. Population I stars are relatively young and metal rich, like our Sun. HD 140283 is possibly a Population III star, or no less than a Population II.
You are right. Thanks for correcting me.
Ann
Howdy y’all. I just noticed the additional comments about the question I raised and Anthony answered re the distinctions between dwarf elliptical galaxies and large globular clusters. Just to be clear, it was these two objects alone that I was referring to in my last comment.
And Ann, please don’t feel too bad ‘bout yer a gettin’ yer stellar populations all reversed and all. Long standing astronomical tradition has got us all locked into a confusing, kinda backassward nomenclatural convention here, hasn’t it? (Pop I young, Pop II old, and Pop III so ancient that da ain’t no mo’.)
And Ann, while I’m truly obliged fer yer a linkin’ ta
dis here,‘bout that thar Methuselar star; (‘cus it was, in my ENORMOUSLY humble opinion, one of the best threads ever, and I’m so glad you both started it and recalled it to our attention), I’m just a tad mifftified as well. Did ya really think that I needed schoolin’ ‘bout dis here subject, when we had such an interesting conversation at the end of it?
Bruce, an armchair nuclear astrophysist, who (according to my wife) can’t pronounce the word nuclear (along with other notable Texans). There’s only two syllables in nuclear, right?
My apologies to any school marms who may have been offended.
[quote="Ann"][quote]BDanielMayfield wrote:
Thanks Anthony. The range of ages of the stars inside these objects was something that hadn't occured to me. Pop I stars inside an object would mean that it wouldn't be a globular cluster, as their stars are all extremely old.[/quote]
That is not actually true. If you check out [url=http://asterisk.apod.com/viewtopic.php?p=193748#p193748]this topic[/url], you can read about a Population I star that is only 190 light-years away from us. This star is extremely metal-poor, and astronomers consider it the oldest star they know. But this star is not located in a globular cluster. Although I haven't checked, I would guess that this star is a halo object, and that it is passing us by in its orbit around the center of the Milky Way.
It is true that stars in the bulge of a galaxy tend to be metal-rich even though they are old. Since they are metal-rich, they most certainly don't belong to Population I. They were born from gas that had been recycled through several generations of stars. But can we be sure that there are no Population stars in the bulges of galaxies? Normally we can't be sure of this at all. [url=http://starryvistas.net/Gallery/NGC6522-NGC6528/NGC6522-2008-06-02-medium.jpg]This picture[/url] shows two globular clusters that are embedded in the bulge of the Milky Way. These globulars are just passing through, but they will likely lose some stars during their crossing of the bulge. Will the "lost stars" end up in orbits that really make them true members of the bulge? I think that is unlikely.
So it is an interesting question if there are any Population I stars in M60-UCD1 or in M32. Perhaps there aren't any. If Population I are either halo objects or members of globular clusters, then there may not be any such stars in a galaxy that has been whittled down to its bulge.
Ann[/quote]
[quote="Ann"][quote]Bystander wrote:
I think you have your populations confused. Population I stars are relatively young and metal rich, like our Sun. HD 140283 is possibly a Population III star, or no less than a Population II.[/quote]
You are right. Thanks for correcting me.
Ann[/quote]
Howdy y’all. I just noticed the additional comments about the question I raised and Anthony answered re the distinctions between dwarf elliptical galaxies and large globular clusters. Just to be clear, it was these two objects alone that I was referring to in my last comment.
And Ann, please don’t feel too bad ‘bout yer a gettin’ yer stellar populations all reversed and all. Long standing astronomical tradition has got us all locked into a confusing, kinda backassward nomenclatural convention here, hasn’t it? (Pop I young, Pop II old, and Pop III so ancient that da ain’t no mo’.)
And Ann, while I’m truly obliged fer yer a linkin’ ta [url=http://asterisk.apod.com/viewtopic.php?p=193748#p193748]dis here[/url],‘bout that thar Methuselar star; (‘cus it was, in my ENORMOUSLY humble opinion, one of the best threads ever, and I’m so glad you both started it and recalled it to our attention), I’m just a tad mifftified as well. Did ya really think that I needed schoolin’ ‘bout dis here subject, when we had such an interesting conversation at the end of it?
Bruce, an armchair nuclear astrophysist, who (according to my wife) can’t pronounce the word nuclear (along with other notable Texans). There’s only two syllables in nuclear, right?
My apologies to any school marms who may have been offended. :lol2: