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Astronomical Observatory: Cool Images

Astr110 Photography Projects, Fall 2006

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Open Cluster (M103), Eric Nondahl

Helix Nebula

Discovered by Pierre Méchain in 1781, M103 is an open star cluster. This means that the member stars were formed from the same dust cloud. The stars are now moving apart from each other and will eventually separate completely. The cluster is about 8,000 light years away and about 15 light years across. It is moving towards us at 37 km/sec. The stars in the cluster are about 25 million years old.

Most of the bright stars in the cluster are tinted blue, which means they are younger stars. The brightness is due to a large mass. The large red giant star in the center of the cluster has moved into the red stage where it is no longer burning hydrogen. This means that the cluster is young, but old enough for the most massive star to have moved to the red giant stage. This process takes anywhere from 2 million years for stars with large mass to billions of years for stars with less mass. For comparison, our sun has a much lower mass and is about 4.5 billion years old, and has not reached this red giant stage.

Hartmut, Frommert. "Messier 103." SEDS Homepage. 9 Dec. 1999. Students for the Exploration and Development of Space. 16 Nov. 2006 <>.

Bill, Arnett. "The Sun." A Multimedia Tour of the Solar System. 25 Aug. 2006. 16 Nov. 2006 <>.

Right Ascension (J2000) 01:22:00
Declination (J2000) 60:03:20
Filters used blue(B), green(V), red(R)
Exposure time per filter 5x10 seconds in VR, 5x20 seconds in B
Date observed

October 18, 2006 (BVR)





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