The Wild Duck Cluster is an open cluster of stars in the constellation Scutum. It was discovered by Gottfried Kirch in 1681. Charles Messier included it in his catalogue of diffuse objects in 1764. Its popular name derives from the brighter stars forming a triangle which could resemble a flying flock of ducks. The cluster is located just to the east of the Scutum Star Cloud midpoint.
Open cluster Messier 11 in Scutum
A portion of M11, imaged by the Hubble Space Telescope
The blue stars in the centre of the image are the young, hot stars of the cluster.
M11 is visible with binoculars in the constellation of Scutum.
An open cluster is a type of star cluster made of tens to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and many more are thought to exist. Each one is loosely bound by mutual gravitational attraction and becomes disrupted by close encounters with other clusters and clouds of gas as they orbit the Galactic Center. This can result in a loss of cluster members through internal close encounters and a dispersion into the main body of the galaxy. Open clusters generally survive for a few hundred million years, with the most massive ones surviving for a few billion years. In contrast, the more massive globular clusters of stars exert a stronger gravitational attraction on their members, and can survive for longer. Open clusters have been found only in spiral and irregular galaxies, in which active star formation is occurring.
The Pleiades is one of the most famous open clusters.
Mosaic of 30 open clusters discovered from VISTA's data. The open clusters were hidden by the dust in the Milky Way. Credit ESO.
The resonant star cluster NGC 3590
NGC 265, an open star cluster in the Small Magellanic Cloud