ASTRO: NGC 7789 Open cluster

NGC 7789 is an open cluster in Cassiopeia. It is one of my favorite
visual star clusters in my 10" f/5 scope. It is thought to be about
8000 light years distant and about 1.6 billion years old. Its most
massive stars have turned to red giants that seem clustered on the
western edge of the cluster. The blue A and F stars are still on the
main sequence and give rise to the blue color stars that dominate the
rest of the cluster. The cluster was discovered by Caroline Herschel in
1783. It is about 16 minutes of arc across which translates to about 37
light years in diameter at 8000 light years. If there are any
inhabitants of a star in the cluster they would have a rather bright
starry sky to wonder about with a sky full of Sirius like stars shining
down on them along with a few far brighter red giants.

Dreyer's description reads: "Cluster, very large, very rich, very much
condensed, stars of 11th to 18th magnitude." I'm not sure I agree with
the "very much condensed" however. Sure seems rather even in my image
and that agrees with my visual impression in the 10".

14" LX200R @ f/10, L-10x5' RGB=2x10'x3, STL-11000XM, Paramount ME

Reduced to 1.5" per pixel to reduce bandwidth.

Rick
--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".

very colorful.... lots of red and blue stars

nice image


"Rick Johnson" wrote in message
ter.com...
NGC 7789 is an open cluster in Cassiopeia. It is one of my favorite
visual star clusters in my 10" f/5 scope. It is thought to be about
8000 light years distant and about 1.6 billion years old. Its most
massive stars have turned to red giants that seem clustered on the
western edge of the cluster. The blue A and F stars are still on the
main sequence and give rise to the blue color stars that dominate the
rest of the cluster. The cluster was discovered by Caroline Herschel in
1783. It is about 16 minutes of arc across which translates to about 37
light years in diameter at 8000 light years. If there are any
inhabitants of a star in the cluster they would have a rather bright
starry sky to wonder about with a sky full of Sirius like stars shining
down on them along with a few far brighter red giants.

Dreyer's description reads: "Cluster, very large, very rich, very much
condensed, stars of 11th to 18th magnitude." I'm not sure I agree with
the "very much condensed" however. Sure seems rather even in my image
and that agrees with my visual impression in the 10".

14" LX200R @ f/10, L-10x5' RGB=2x10'x3, STL-11000XM, Paramount ME

Reduced to 1.5" per pixel to reduce bandwidth.

Rick
--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".