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Anne’s Picture of the Day: Open Cluster Messier 39
read more at Anne’s Astronomy News http://annesastronomynews.com/
April 18, 2013
Messier 39, an open star cluster in Cygnus
Image Credit: Heidi Schweiker/WIYN and NOAO/AURA/NSF
Messier 39 (also known as NGC 7092) is a very loose open star cluster of about 7 light-years across, located at a distance of some 825 light-years away from Earth in the constellation of Cygnus (the Swan), while it is approaching us at approximately 28 kilometers per second. It is between 230 and 300 million years old.
Open clusters contain fewer and younger stars than globular clusters. Also unlike globular clusters, open clusters are generally confined to the plane of our Galaxy.
Messier 39 is one of the larger open clusters on the northern sky, and despite its looseness, the cluster is well defined. It is shaped as an equilateral triangle – the southerly side aligned about East-West – with a bright star at each corner, and about 25 fainter stars within.
Thirty stars are proven members of Messier 39 and many of them are grouped in pairs. They are at most 300 million years old, so they are much younger than our Sun which is about 5,000 million years old. All stars are main sequence stars, with the brightest stars apparently just before the point of evolution toward the red giant phase. It has a total luminosity of 830 suns.
Small telescopes will easily see a bright handful of stars while larger ones will resolve many more faint members and pairs of this open cluster.
This image is a combination of 33 images taken with the Mosaic camera at the WIYN 0.9-meter telescope on Kitt Peak, Arizona, on the night of September 15th, 2003.
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2013-04-18 05:45:54
Source: http://annesastronomynews.com/annes-picture-of-the-day-open-cluster-messier-39/
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