AAO image reference AAT 112. « Previous || Next » Top left is
NE. Image width is about 15 arc min Image and text © 1992-2010,
Australian Astronomical Observatory, photograph by David Malin.
Messier saw this fine open cluster in 1780, indeed it is hard to
miss, being almost 30 arc minutes in diameter. The cluster is
about 2500 light years away in the direction of Cancer. NGC 2682
is among the oldest open clusters, with an age of about 4
billion years, almost as old as the Sun. Being so old (for an
open cluster) and so nearby it has been extensively studied
since all its stars are at essentially the same distance.
Because this eliminates two variables, distance and age,
studying stellar evolution in such a cluster is greatly
simplified. Nonetheless there remain large differences in values
for the absolute age of the cluster and its mass, which is over
1000 solar masses. This photograph deliberately was taken on the
AAT under conditions of poor seeing and with a series of short
(4 minute) exposures. The idea was