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Star Clusters. Pre clusters. Courtesy University of Oregon. Types. Associations Ironically, a dis associating open cluster Big Dipper/Ursa Major Open Clusters ~1000 stars Found in the spiral arms of the galaxy Mostly young hot stars Pop I Globular Clusters ~1 million stars
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Pre clusters Courtesy University of Oregon
Types • Associations • Ironically, a disassociating open cluster • Big Dipper/Ursa Major • Open Clusters • ~1000 stars • Found in the spiral arms of the galaxy • Mostly young hot stars • Pop I • Globular Clusters • ~1 million stars • Found in the galactic halo • Mostly old stars • Pop II
What stellar ages tell us:The Turnoff Point • We can know something about the age of a cluster of stars by looking at when the most massive stars turnoff the MS Two animations follow
M80, one of the densest of the 147 known globular star clusters in the Milky Way; 28,000 LY
IR image of the Arches Cluster • About 33 pc from the galactic nucleus • 100 O class stars • Globular or Open?? • Most densely packed cluster observed • Separation ~ light weeks apart Not these arches ->
