Reply With QuoteNice one Wollery, if you were close I'd get you a celebratory drink :)
You'll have to make do with a virtual one for now
One of the stars from the catalogue that I compiled for my thesis turns out to be the coolest extreme subdwarf yet discovered!
http://www.journals.uchicago.edu/cgi...160002982Guest
Nice one Wollery, if you were close I'd get you a celebratory drink :)
You'll have to make do with a virtual one for now
I thought 'coolest extreme subdwarf' were a rock band
In all seriousness.....well done
YAY! You are a star, and you discovered a star! How lovely. :)
I can't get to see it. The link tells me to allow cookies and won't let me in,
I don't disable cookies on my browser as I don't think they're much of a risk.
.
Cool. Well done and I'm very jealous due to my extreme amateur status.
The speed of light, expressed in FFF Units, is 1.8 mega-furlongs per micro-fortnight, or approximately 1.8 terafurlongs per fortnight.
Gravity makes the heart grow heavier.
Any use of this product, in any manner whatsoever, will increase the amount of disorder in the universe. Although no liability is implied herein, the consumer is warned that this process will lead to the heat death of the universe.
Same problem here.Originally Posted by John Jackson
I can't get to see it. The link tells me to allow cookies and won't let me in,
I don't disable cookies on my browser as I don't think they're much of a risk.
The speed of light, expressed in FFF Units, is 1.8 mega-furlongs per micro-fortnight, or approximately 1.8 terafurlongs per fortnight.
Gravity makes the heart grow heavier.
Any use of this product, in any manner whatsoever, will increase the amount of disorder in the universe. Although no liability is implied herein, the consumer is warned that this process will lead to the heat death of the universe.
What's an extreme subdwarf?
.
it's either the base-jumping younger brother of Bashful
or this might help...
http://www.physics.udel.edu/~gizis/research.html
The speed of light, expressed in FFF Units, is 1.8 mega-furlongs per micro-fortnight, or approximately 1.8 terafurlongs per fortnight.
Gravity makes the heart grow heavier.
Any use of this product, in any manner whatsoever, will increase the amount of disorder in the universe. Although no liability is implied herein, the consumer is warned that this process will lead to the heat death of the universe.
Yep, that's the paper. LEHPM 2-59 is the star.
Sorry, maybe I should have explained the term extreme subdwarf. Main sequence (hydrogen burning) stars come in three basic types, dwarfs, like the Sun, which are metal rich , subdwarfs, which are metal poor, and extreme subdwarfs, which have virtually no metals at all. The extreme subdwarfs were the very first stars to form in our Galaxy, and only the very low mass ones are still around, the rest having burned all their hydrogen. They're fairly rare.
It should be noted that for the purposes of stellar astronomy 'metal' means anything that isn't hydrogen, and 'hydrogen burning' means conversion of hydrogen to helium by fusion in the core of a star.
Right, I'm with you now.
I studied stars and the interstellar medium at some point on my OU degree and if you'd called it a brown dwarf I would have got it first time. :P
So you discovered it yourself wollery!! Nice one. 8)
.
No, no, no, no, no. This is not a brown dwarf.
Brown dwarfs do not have stable core fusion reactions since they have too little mass to get their cores hot and dense enough, and as such are not really stars.
This is a star, but it's very cool, old and is seriously lacking in elements other than hydrogen. The more massive extreme subdwarfs were formed from the extremely metal poor protogalactic cloud, created heavier elements in their cores, and these elemants were then thrown out into the interstellar medium where they went into making new stars which had more heavy elements (the subdwarfs), and the more massive of these stars in turn produced yet more heavy elements which went to make up stars with higher metallicity, like our Sun.
One of the "holy grails" of modern stellar evolution is the extreme subdwarf brown dwarf, which, since it wouldn't have undergone core fusion, would still have exactly the same chemical makeup as the protogalactic cloud. This would tell us a lot about how the Galaxy formed as well as indicating how accurate the models of big bang nucleosynthesis are.
Hmmm....
I'm assuming that by 'subdwarf' that the star was never massive enough for nuclear fusion to have began (what I would call a brown dwarf). In the quote (bolded) you say that extreme subdwarfs created heavier elements...
So I remain confused as to what a subdwarf and an extreme subdwarf are. :(
.
Yeah, it's confusing. A lot of astronomical terminology is, like "metal" being used to mean any element other than hydrogen! :D
Subdwarfs were named long before brown dwarfs were even thought of. They were called subdwarfs because they are less luminous than dwarf stars which have the same spectral type. The reasons for this lower luminosity are complicated, and I won't try to explain them here.
The important point is that subdwarfs and extreme subdwarfs are stars which undergo stable core hydrogen fusion reactions, just like the Sun. They simply have a different chemical makeup.
Posting Permissions
Bookmarks