| Ursa Major Moving Group |
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Information AboutUrsa Major Moving Group |
| CATEGORIES ABOUT URSA MAJOR MOVING GROUP | |
| stellar associations | |
| ursa major constellation | |
| SHOPPER'S DELIGHT | |
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DISCOVERY AND CONSTITUENTS All stars in the ''Ursa Major Moving group'' are in roughly the same location in the Milky Way Galaxy , are moving in roughly the same direction at roughly the same speed, contain roughly the same mix of Metal s, and, based on stellar theory, appear to be roughly the same age. Based on the ages of its constituent stars, the ''Ursa Major Moving group'' is believed to have once been an Open Cluster , having formed from a protostellar Nebula approximately 500 million years ago, which is fairly young. Since that distant time in the past, the sparse group has been scattered over a region about 30 by 18 Light-year s, whose center is currently some 75 Light-year s away, making it the closest Cluster-like Object to the Earth . The ''Ursa Major Moving Group'' was discovered in 1869 by Richard A. Proctor , who noticed that, except for Dubhe and Alkaid , the stars of the Big Dipper Asterism all have Proper Motion s heading towards a common point in Sagittarius . Thus, the Big Dipper, unlike many constellations or asterisms, is actually largely composed of related stars. Some of the brighter stream members include and Stream Stars . GROUP MEMBERS Current criteria for membership in the moving group is based on the stars' motion in space. This motion can be determined from the . Based on their distances (measured with Hipparcos) and Apparent Magnitude , the Absolute Magnitude can be used to estimate the age of the stars. The stars in the moving group appear to have a common age of about 500 million years. Core stars The core of the moving group consists of 14 stars, of which 13 are in the Ursa Major Constellation and the other is in the neighboring constellation of Canes Venatici . The following are members of the moving group closest to its center. These stars are all in Ursa Major except where indicated.
Stream stars There is also a "stream" of stars which are likely members of the Ursa Major Moving Group, scattered more widely across the sky (from Cepheus to Triangulum Australe ). Only stars with Bayer Designation s or Flamsteed Designation s are listed here.
Non-Members The bright, nearby star Sirius , was long believed to be a member of the group, but may not be, according to research in 2003 by Jeremy King et al. at Clemson University which seems to indicate that it is too young to be a member. Our Solar System is in the outskirts of this stream, but is not a member, being about 10 times older. Our Sun merely drifted in along its 250 million year galactic orbit, and 40 million years ago was nowhere near these stars. EXTERNAL LINKS
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