Open star clusters are widely distributed in our galaxy and represent a loose collection of stars which number from a few dozen to a few
hundred stars and are weakly-held gravitationally. Perhaps the three most famous such open clusters are the Pleiades (M45) in Taurus, the
Beehive (M44) in Cancer and the double cluster in Perseus. They are all characterized with a handful of hot and white prominent stars and
nebular material surrounding these stars.
Note: Open cluster NGC 6705 in Scutum depicted below is a rich dense cluster comprised of nearly 3000 member stars which are of uniform brightness and very well detached from the background sky. The cluster spans 14 arc-minutes in diameter or almost half the apparent diameter of the full moon. Also known as the Wild Duck cluster, NGC 6705 lies at a distance of 6,000 light-years away and is dated at a mere 220-250 million years-old and as evidenced by the predominance of white hot stars in the image below. The cluster is best observed using low magnifications (50-100x) during mid-summer as it appoaches the southern meridian near midnight. NGC 6705 was discovered by the German astronomer Gottfried Kirch (Berlin Observatory) in 1681.
Please click on the image below to display in higher resolution (1200 x 950)
Wild Duck Cluster
Cr 391, OCL 76
I 2 r
RA / Dec:
18h 51m 04s /
-06° 15' 52"
Jul 25-26, 2009
22:30 - 00:35 UT+3
AP 160 f/7.5 StarFire EDF
AP 1200GTO GEM
AstroDon TruBal CRGB
1.17" per pixel