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M 79
32 of 111

M 79

February 19, 2005
Globular Cluster M79 (NGC 1904), class V, in Lepus

Right Ascension: 05 : 24.5 (h:m)
Declination: -24 : 33 (deg:m)
Distance: 42.1 (kly)
Visual Brightness: 7.7 (mag)
Apparent Dimension: 9.6 (arc min)

Discovered 1780 by Pierre Méchain.

Globular cluster M79 was found by Pierre Méchain on October 26, 1780, and reported his discovery to his friend and colleague, Charles Messier, who determined its position and included it in his catalog on December 17, 1780. It was first resolved into stars and recognized as a globular cluster by William Herschel in about 1784.

M79 is a beautiful globular cluster at a quite unusual location in the sky: Most globulars are grouped around the Galactic center, but this is one of the few which are situated in the other hemisphere, i.e. it is beyond us for hypothetical observers in the central stellar bulge of our Milky Way galaxy. It is little over 40,000 light years from us, but about 60,000 light years from the galactic center.

At this distance, M79's apparent diameter of 9.6 minutes of arc corresponds to a linear extension of about 118 light years. This cluster is slightly elliptical, extended at position angle 45 deg, and has only 7 known variables. It is receding from us at about 200 km/sec.

In 2003, it was found that M79 is perhaps a rather new immigrant into the globular cluster system ot our Milky Way: It may come from, or still be a member, of the remnant globular cluster system of the Canis Major Dwarf galaxy, which is currently undergoing a very close encounter with our Galaxy, and in progressive state of dissolution. Together with M79, three more globular clusters are suspected to have immigrated from the Canis Major Dwarf: NGC 1851, NGC 2298, and NGC 2808.

About 0.5 degrees to the SW of M79 lies the 5.5 mag star ADS 3954 with its 7th mag companion, separated by 3".


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