Astral Imaging at Dogwood Ridge Observatory

Latitude: 37°48'51.0" N"
Longitude:78°23'41.0"W
Scottsville, Virginia 24590

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Clusters

Globular These are massive numbers of stars, approximately ten thousand to one million, that are gravitationally bound. They populate the halo or bulge of galaxies with significant concentration toward the Galactic Center. Studies of globular clusters show that they are considerably lower in heavy element abundance than stars that form in the disks of galaxies such as our sun. They are determined to be of 12-20 billion years old.
Open These are also known as Galactic clusters. They are physically related groups of stars held together by means of gravitational attraction. Believed to have originated from large cosmic gas and dust clouds in the Milky Way, they continue to orbit the galaxy through the disk. New open star clusters are forming in diffused nebula as you read this. These are composed of young population I stars. Open clusters are found mainly in the same regions as that of diffuse nebula, most commonly in spiral arms in disk galaxies and irregular galaxies. Open clusters are found in the band of the Milky Way.

Most open clusters have only a short life as stellar swarms. As they drift along their orbits, some of their members escape the cluster, due to velocity changes in mutual closer encounters, tidal forces in the galactic gravitational field, and encounters with field stars and interstellar clouds crossing their way. An average open cluster has spread most of its member stars along its path after several 100 million years; only few of them have an age counted by billions of years. The escaped individual stars continue to orbit the Galaxy on their own as field stars: All field stars in our and the external galaxies are thought to have their origin in clusters.

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  Last Modified :01/23/09 03:40 AM