Milky Way
Globular
Clusters
Index
1. Introduction
2. Orbits
3. Omega Centauri
4. 47 Tucanae
5. 47 Tuc Core
6. 47 Tuc Blue Stragglers
7. M4
8. M5
9. M10
10. M13
11. M15
12. M22
13. NGC 6522
14. Galactic Centre Chart
15. List of MW Globulars
16. Credits and Links
M15
M15 or NGC 7078) is in constellation Pegasus. Its distance is about 33,600 light-years. It is too dim to be seen with the unaided eye (visual magnitude 6.2). In small telescopes, it appears as a fuzzy star. Telescope apertures of 6 inches or greater reveal individual stars. Its brigtest stars are magnitude 12.6.
M15 is the most densely packed of the Milky Way's globulars. It has undergone a core collapse contraction. The density of stars at the centre is enormous. It may harbor a central black hole.
With an estimated age of 13.2 billion years, it is one of the oldest globular clusters. Eight pulsars have been found in M15 including a double neutron star system, M15 C. M15 houses one of only four planetary nebulae known in a globular cluster, Pease 1, discovered in 1928. It is visible in image 10 above. See the source site for details.
Sources:
Messier 15 - Wikipedia
Astro Images, Jason Ware
NOAO Image Gallery
UA Astronomy Messier Picture Gallery, Bill Keel
M15, the densest star cluster - Hubble Site
Planetary nebula in M15 - Hubble Site