Re: [APML] Re: M13 star colors

[Dean Jacobsen <deanjacobsen@earthlink.net>]

At 09:38 PM 6/11/2002 -0700, you wrote:
> Dean,
>  
>     That's what I thought (old
> stars...) but many good CCD images (and some good film images, too) show
> about a 50% population of blue stars... I take these to be younger hot
> stars to emit that color. The idea that globulars are very old remnants
> of the galaxy formation or remnants of some gallactic disturbance that
> have no current young star activity has to be suspect... there is no way
> all these CCD tricolor shots can be wrong... CCD cameras are linear and
> the filters are accurate enough to be believable... it also does not
> explain the presence of both young AND old stars in the image...
> indicating no bias one way or the other. Here is a case where there is a
> lot of surprising evidence that refutes the "popular"
> theories... most of astronomical theory is just that...theory, and I
> think someone needs to take another look at globulars. Those are blue
> stars...
>  
>     
> Tony

Tony, I don't make the news, I just report it. <G>  

The information that I relayed to you is Astronomy 101 stuff.  I
would say that most of the tri-color CCD shots that you see taken by
amateurs are way off in their presentation of color for globular clusters
for the simple reason that most CCD imagers have not taken the time to
calibrate their system using a known star type.  Have you?

There is no dispute that I am aware of among the scientific community
that there has not been star formation in the globular clusters
for the last few billion years.  As far as I am aware, this is not a
"popular" or "fad" theory.  This was confirmed
years ago through extensive analysis of the component stars of globular
clusters.  There is no dispute that I am aware of for the assertion
that all stars in globular clusters have VERY LOW metal content. 
Thus, they cannot be second generation or later stars formed in part from
the remnants from earlier supernova explosions.

Globular clusters do contain small populations of "blue
straggler" stars.  I can't remember the reason for their
color.  However, they are the minority, not the majority.

Best Regards,

Dean Jacobsen
www.astrophoto.net