Globular cluster M15

About this image
This is a thirty-second exposure taken on the night of September 1st 1994 (UT of observation 02/09/94:05:47) with the 1k detector. This photograph shows a region 200 arc seconds square which has been compressed in brightness (approximately a double logarithm) to show both bright and faint features. This image shows the capabilities of the WIYN telescope rather better than most observations that night, since it has a "seeing" measurement (average FWHM of several stars) of about 0.8 arc seconds.
Orientation: N up, W to the left.

About this object
Globular clusters are tightly packed agglomerations of hundreds of thousands of stars. They have a spherical shape and are themselves distributed in a spherical halo around our Galaxy, the Milky Way. M15 (NGC 7078) is an excellent example in the constellation Pegasus. It actually covers a region more than three times the extent seen in this image. There is a significant central light excess in M15, over and above the brightness that would be expected from the normal dynamical models of globular clusters. An early suggestion that this cusp could be caused by a few thousand solar mass black hole seems less likely in the light of high resolution observations by the Hubble Space Telescope, although no final verdict is yet agreed upon by all researchers.

Location: 21 30.1 +12 10 (2000.0), distance: about 34000 light years.

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