[AZ-Observing] Re: Christmas observing
- From: Michael Collins <cal_donley@xxxxxxx>
- To: az-observing@xxxxxxxxxxxxx
- Date: Sun, 25 Dec 2011 10:38:25 -0700
> It is usually stated that about half the stars in the sky are
> binaries. I was wondering if the same holds true for the members of
> clusters. Are open clusters for the most part too far for us to
> resolve binaries or are the companions too faint, or are cluster
> members for the most part actually single? I should note that I have
> looked at the Pleiades and the Hyades and note that their members are
> nearly all single, too.
Well, consider that most known binaries are spectroscopic rather than
visual, so many "single" stars in the clusters you mention may in fact
be binaries. I haven't looked for any studies, but I suspect that the
population of binaries in clusters is similar to the population of
binaries in the galaxy in general. After all, most stars are formed in
clusters to begin with -- we see many stars (including binaries) as
individual objects because open clusters are dispersed after a few
orbits around the galactic center. The life of a sun-like star is far
greater than the time it takes for the cluster it formed within to be
scattered across a huge volume within the galaxy.
-- Mike --
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cal_donley@xxxxxxx
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