OPEN CLUSTERS

M 67 M67 is an open star cluster in the constellation Cancer. One of the oldest known such clusters, M67 is believed to be 10 billion years old. It contains approximately 500 stars within its 12 light year diameter and is located some 2500 light years away. This full color image was created from nine images taken in the BVR pass-bands at the Burrell Schmidt telescope of Case Western Reserve University's Warner and Swasey Observatory. The Burrell Schmidt is located on Kitt Peak, near Tucson, Arizona. The images were taken in January 1997. North is at the top with east to the left.
M 37 M37 is an open star cluster about 4,600 light years away in the constellation Auriga. Its diameter is 25 light years, and it contains about 150 stars.
M 52 Open star cluster M52 (NGC7654) (upper left) and the Bubble emission nebula (NGC7635) (lower right) are located in the constellation Cassiopeia. This combination of CCD images from the Kitt Peak Burrell Schmidt telescope extends more than a degree across the sky (twice the diameter of the full moon). Zoom in for a magnified view.
M 45 M45 is a beautiful open cluster 450 light years away in the constellation Taurus.
M 46 M46 is a rich open star cluster in the constellation Puppis. Within a diameter of 28 arc minutes, or about 30 light years at its distance of 5400 light years, M46 contains over 150 bright stars and a total population perhaps over 500. M46 is probably around 300 million years old. It is also noteworthy for the presence of the planetary nebula NGC2438 on its northern edge (up and left of center). NGC2438 is almost certainly not physically associated with M46 due to is probable evolutionary history, its significantly different velocity, and a distance estimate only a little more than half the distance to M46.

There is also an interesting extremely red object to the east (left) of the planetary. This is not a camera flaw, but a bipolar protoplanetary nebula with the sonorous name OH231.8+4.2 (also IRAS 07399-1435, but that doesn't sound as good). It is also in the foreground, even closer to us than is NGC2438. This rather complex, somewhat controversial, object contains two expanding lobes showing both emission and reflection nebulosity. Most of this nebular material was ejected from a central star during its evolution through the asymptotic giant branch. It's also a very interesting object to observe at infrared wavelengths. 

This approximately true-color image was created from eleven images taken in the BVR pass-bands at the Burrell Schmidt telescope of Case Western Reserve University's Warner and Swasey Observatory. The Burrell Schmidt is located on Kitt Peak, near Tucson, Arizona. The images were taken in September 1997.
Double Cluster The open clusters NGC 869 and NGC 884 are located in Perseus. These are visible to the naked eye on clear dark nights.
M 103 Open cluster M103 is 8,000 LY away in the constellation Cassiopeia. Notice the red giant star near the center.
Jewel Box The Jewel Box is an open cluster containing about 100 stars including one red supergiant. The Jewel Box is 20 LY in diameter and 7,500 LY away in the southern constellation Crux.
Cluster Formation Computer simulation of the formation of a star cluster from an interstellar molecular cloud. The cloud has an initial mass of 50 solar masses, an initial radius of 1.2 light years, and an initial temperature of 10 Kelvin.
M35 Open cluster M35 is 2,800 light years away in the constellation Gemini. It contains about 2,500 stars and has a diameter of about 30 light years. Another more distant open cluster, NGC 2158, also appears in the lower right of the image.