Jack Kramer

One of the brightest and easiest-to-find open clusters is M41 in Canis Major. It's located only about 4o south of Sirius -- the brightest star in our sky. Moreover, it's visible in binoculars and in finder scopes. The drawback is that the low declination means it may be swimming in a lot of skyglow; obviously, the picture below shows how it should look in a really dark sky.

The cluster contains about one hundred stars, ranging in brightness from 7th to 13th magnitude. Near the center is the brightest member, which happens to be a reddish-colored K-type star. This is an unusual situation, since most open clusters contain a predominance of hot young stars that appear white or blue in color. There are other more faint K-type members in M41, as well. The fact that some members are older and cooler than the rest has long been a source of puzzlement to astronomers. This isn't the only open cluster containing a red member, but it is a relatively infrequent occurrence...and in theory, shouldn't occur at all.

Published in the February 1996 issue of the NightTimes