Re: How does this galaxy change formation theories?


"Yousuf Khan" <yjkhan@xxxxxxxxx> wrote in message
news:1128008219.073906.114860@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Greg Neill wrote:
>> > If this young galaxy is so massive and so red like an old galaxy, would
>> > that push back the age of the Universe several billion years?
>>
>> No, a simpler explanation would be that an unusually large
>> knot of matter happened to exist that formed a galaxy
>> very early. The Big Bang theory does not rule out a certain
>> amount of unevenness in the distribution of matter.
>
> But how does that explain all of the *old* red stars in this galaxy?
>
> I believe red giants are only produced from main sequence stars, not
> too different from our Sun, not the massive blue giants that usually go
> supernova very young. Those stars last billions of years before they
> become red giants. How could there be multi-billion year old stars in a
> galaxy that shouldn't be more than 800 million years old?

I really don't know much about this but one point
strikes me. This paper refers to the findings:

http://www.arxiv.org/abs/astro-ph/0509605

In it, Panagia et al (including Mobasher) say

"Mobasher et al. (2005) conclude that the stars
were formed at z> 9 (i.e. an age of the Universe
t_U < 540 Myr), and possibly as high as z?12-20"

The range z=15 to 20 is where Pop III stars are
expected to be produced and they are anticipated
to produce predominantly high mass stars with mass
> 100 M_Sun and produce significant amounts of
metals. That might act as a local dust changing
the spectrum by absorbtion and re-emission.

http://www.arxiv.org/abs/astro-ph/0305333

What I haven't spotted yet is an estimated lifetime
for these large stars.

George


.

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