[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]
[APML] Re: M13 star colors
Hi Tony,
Interesting image because I believe that it is generally accepted by the
scientific community that, with a few exceptions, the stars that make up
globular clusters are nearly all "Population II" stars.
Population II stars are very old with very little metal content, were
formed very early in the history of the universe and have typical ages
believed to be in the range of 11 to 13 billion years old [some estimates
range from 9 to 13 billion years]. Stars that populate globular
clusters are typically pale yellow to orange and red in color with
temperatures of 2700 Kelvins for the pale yellow ones [give or take a few
degrees]. The orange and red ones are even cooler.
Thus, one would not expect to see a large population of blue stars in any
globular cluster because all Type O and B stars that may have been in
globular clusters have long since evolved to white dwarfs, a Type II
supernova that leaves a neutron star, or a Type II supernova that leaves
a black hole. The main sequence life spans for Type O and B stars
are believed to range from 1 million to 10 million years with no
indication that new stars have formed in globular clusters over the last
few billion years.
Check out:
http://www.aao.gov.au/images/captions/aat089.html
and
http://www.aao.gov.au/images/captions/aat076.html
Also check out:
http://www.seds.org/messier/glob.html
Best Regards,
Dean Jacobsen
www.astrophoto.net
At 05:56 PM 6/11/2002 -0700, you wrote:
Hi
Folks,
...snip... I used my
usual reduction techniques and PS for image extraction from the 16 bit
data... what I found was beautiful and dare I say it, scientifically
significant... the stars really showed their colors. There are two main
types... blue, and yellow-orange. Here and there some very red stars are
visible... very old carbon stars? At any rate, not your usual M-13
shot.
http://www.astrophoto.com/M13CCD.htm
Have a good
one,
Tony