This is a 5-minute exposure taken with an SBIG ST-9E CCD camera through Kopernik's 20 inch F/8.1 telescope. The field of view is about 8x8 arc minutes, with North at the top.
Charles Messier (Jan. 4th, 1781): ''Nebula without star in the Scorpion, between the stars g. (now rho Ophiuchi) and delta; compared with g. to determine its position. This nebula is round, the center brilliant and it resembles the nucleus of a little comet, surrounded with nebulosity. M. Mechain saw it on 27th Jan. 1781"
W. Hershel (1785): 'It is remarkable that the 80th Nebuleuse sans Etoiles of the Connaissance des Temps, ...... is one of the richest and most compressed clusters of small stars I remember to have seen.....'
M-80 (Click here for a Hubble Space Telescope image), one of the densest of the 147 known globular star clusters in the Milky Way galaxy. Located about 28,000 light-years from Earth, it contains hundreds of thousands of stars, all held together by their mutual gravitational attraction. Globular clusters are particularly useful for studying stellar evolution, since all of the stars in the cluster have the same age (about 15 billion years), but cover a range of stellar masses. Every star visible in the Kopernik image is either more highly evolved than, or in a few rare cases more massive than, our own Sun. Especially obvious are the bright red giants, which are stars similar to the Sun in mass that are nearing the ends of their lives.
M-80 is also unusual because it was the site of a nova explosion in the year 1860. Nova outbursts occur when a close companion star transfers fresh hydrogen fuel to a burned-out white dwarf. Eventually the hydrogen ignites a thermonuclear explosion on the surface of the white dwarf, giving rise to the nova outburst.
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George Normandin, KAS
November 18th, 2001