| 21. | Tombaugh 5 is a fairly dim open cluster in Camelopardalis.
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| 22. | The inflorescence may have few or many flowers in a dense or open cluster.
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| 23. | Its discoverers claimed it was the first planet ever discovered in an open cluster.
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| 24. | The outskirts of the galaxy have many young open clusters.
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| 25. | NGC 189 "'is an open cluster in the Cassiopeia constellation.
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| 26. | Partly because of their small total mass, open clusters have relatively poor gravitational cohesion.
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| 27. | NGC 1980 is an open cluster containing a few bright stars including ? Orionis.
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| 28. | NGC 2281 is a small open cluster at a distance of 1, 500 light-years.
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| 29. | M73, also catalogued as NGC 6994, is an open cluster with highly disputed status.
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| 30. | Delta 2 Lyrae is the brightest member of the scattered open cluster Stephenson 1.
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