| Abstract from DBPedia | Star clusters are large groups of stars. Two main types of star clusters can be distinguished: globular clusters are tight groups of ten thousand to millions of old stars which are gravitationally bound, while open clusters are more loosely clustered groups of stars, generally containing fewer than a few hundred members, and are often very young. Open clusters become disrupted over time by the gravitational influence of giant molecular clouds as they move through the galaxy, but cluster members will continue to move in broadly the same direction through space even though they are no longer gravitationally bound; they are then known as a stellar association, sometimes also referred to as a moving group. Star clusters visible to the naked eye include the Pleiades, Hyades, and 47 Tucanae.星団（せいだん、star cluster）は、同じガスから誕生した、互いの重力相互作用によって結びついた恒星の集団。その特徴から散開星団 (英: open cluster) と球状星団 (英: globular cluster) に分類される。 (Source: http://dbpedia.org/resource/Star_cluster) |
