Pleiades (star cluster)

The Pleiades (also known as M45 or the Seven Sisters) is an open cluster in the constellation of Taurus. It is among the nearest to earth of all open clusters, probably the best known and certainly the most striking to the naked eye.

Related Topics:
Open cluster - Taurus

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The distance of the cluster is very important as it is a crucial step in determining the distance scale of the whole universe. The Hipparcos satellite measured a distance for the cluster which was 10% smaller than most previous measurements, but was later found to have suffered from a systematic error when observing the Pleiades. The cluster is now known to lie at a distance of about 135 parsecs (440 light years).

Related Topics:
Universe - Hipparcos - Systematic error - Parsec - Light year

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The cluster is dominated by hot blue stars, which have formed within the last 100 million years. Dust remaining from the formation of the cluster forms faint reflection nebulosity around the brightest stars. The cluster will in time disperse due to gravitational interactions with the spiral arms of the galaxy and giant molecular clouds. The cluster's lifetime will probably be about 250 million years.

Related Topics:
Reflection nebulosity - Spiral - Galaxy - Giant molecular cloud

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