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M15

Messier 15
NGC 7078
Great Pegasus Cluster
Globular Star Cluster
Right Ascension 21h 29m 58s Best Seen 8/15-12/15
Declination 12° 10' 00" Magnitude 6.2
Constellation Pegasus

Actual		 Compared
to Sun
Distance ~33,600 ly --
Diameter 120 ly --
Number of Stars ~100,000 --
Actual Brightness -- 360,000
Age greater than 12 billion years ~2.5
Integrated Spectral Type F3 G2 V

What To Look For Through The Telescope

  1. Recommended eyepiece: 40mm or 80 mm.

  2. When people look through the telescope the cluster will appear similar to a pile of sugar or salt on a table.

M15 Information

  1. This cluster has a slightly elliptical shape.

  2. Although it cannot be seen through the telescope, the northwestern portion of the cluster still has a portion of diffuse nebula.

  3. This cluster is approaching us at about 112 km/sec (70 mi/sec).

  4. The core of M15 is very dense and has a density classification IV and is one of the most densely concentrated clusters of its kind. The cluster is notable for its steep central cusp, with an exceptionally large number of stars orbiting what is likely a central black hole. However, it is not certain whether or not there is a black hole at the center of the cluster.

  5. The first planetary nebula discovered in a globular cluster was found in M15. (Only three more planetary nebulae have been found in other clusters.)

  6. There are several pulsars in M15.

  7. Messier 15 is one of the oldest known globulars in our galaxy. It has an estimated age of 12 billion years and only 1 percent of the Sun’s iron content. The cluster has an absolute magnitude of -9.2, which makes it about 360,000 times more luminous than the Sun.

  8. Messier 15 has an apparent diameter of 18 arc minutes, corresponding to a linear diameter of about 175 light years. The tidal radius of M15 spans 21.5 arc minutes, or about 210 light years from the cluster’s center.
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References
Item Updated Notes
Coordinates 2002-08-14 just “tweaked” a bit
Distance 2002-08-14 http://messier.seds.org/m/m015.html
Actual Brightness 2002-08-14 http://messier.seds.org/m/m015.html
Number of Stars --
Diameter 2002-08-14 http://messier.seds.org/m/m015.html
Age --
Integrated Spectral Type 2002-11-22 SIMBAD
Other 2003-01-13 http://messier.seds.org/m/m015.html
http://antwrp.gsfc.nasa.gov/apod/ap011210.html
http://hubblesite.org/news_release/news/2002-18/year/2002
Uncertainty in black hole existence http://www.sciencedaily.com/releases/2003/01/030110192346.htm