Open Star Cluster M 41 and Sirius

The cluster of the Dog Star

Date: 03.02.02 Time: 21:11 UT Exposure: 25 min
Field of View: 4.5^o x 6.8^o Emulsion: Kodak Ektachrome 200/400 Filter: none
Instrument: f=300mm 1/4.5 Place: Römerstein, Alb Observer: Till Credner

Date:	03.02.02	Time:	21:11 UT	Exposure:	25 min
Field of View:	4.5^o x 6.8^o	Emulsion:	Kodak Ektachrome 200/400	Filter:	none
Instrument:	f=300mm 1/4.5	Place:	Römerstein, Alb	Observer:	Till Credner

The bright star Sirius, alpha CMa or "Dog Star", is with -1.5 mag not only the brightest in the constellation of Canis Major, it is the brightest star of the entire night sky (probably you know the brightest star of our entire sky: Answer). Sirius is a dwarf star of spectral class A 1. It is so bright since it is 26 times more luminous than the sun and, much more important, because Sirius is only about 8.6 lightyears away.

Just 4 degrees south of Sirius lies the splendid open star cluster M 41 (NGC 2287). Under good sky conditions you might catch it with your naked eyes as a nebulous patch. And with a pair of binoculars it is resolved into an impressive group of stars (however, using a telescope at higher magnification does not show the cluster well since it is a quite loose concentration of stars). M 41 is believed to have a distance of 2400 lightyears and an age of about 240 million years. Therefore M 41 lies about 280 times far away in the background of our stellar neighbor Sirius.