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M2
Messier 2
Globular Star Cluster
| Right Ascension | 21h 33m 29s | Best Seen | 9/15-12/15 |
| Declination | -0° 49' 23" | Magnitude | 6.3 |
| Constellation | Aquarius | ||
Actual |
Compared to Sun |
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| Distance | ~37,500 ly | -- |
| Diameter | ~150 ly | -- |
| Number of Stars | 150,000 | -- |
| Actual Brightness | -- | -- |
| Age | greater than 12 billion years | |
| Integrated Spectral Type | F4 | G2 V |
| Density (gram/cubic cm) | -- | -- |
What To Look For Through The Telescope
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Recommended eyepiece: 40mm or 80 mm.
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When people look through the telescope the cluster will appear similar to a pile of sugar or salt on a table.
M2 Information
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M2 is not completely spherical: it looks slightly elliptical in shape.
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Also known as NGC 7089
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It is just visible to the naked eye under extremely good conditions. Binoculars & small telescopes will see the object, but not resolve it to stars. Large telescopes will resolve it to stars, the brightest of which are magnitude 13.1.
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First discovered by 1746 by Jean-Dominique Maraldi while observing a comet with Jacques Cassini.
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Charles Messier rediscovered it in 1760, but described it as a “nebula without stars.”
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William Herschel was the first to resolve it into individual stars in 1783. He described it as, “like a heap of fine sand!”
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It is one of the largest known globular clusters with a dense, rich inner core. The central core has a diameter of only about 3.7 light years across.
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Its tidal radius is about 233 light years, which means that is the distance from its center that it would start losing stars to the Milky Way’s gravitational pull. Everything inside that radius is bound together gravitationally in this cluster.
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The cluster contains about 150,000 stars, including 21 known variable stars. Most of its brightest stars are yellow and red giants.
a. It is fairly symmetrical, with a slight north-south elongation making it look elliptical.
b. Its estimated age is about 13 billion years old.
c. If you want a challenge in a larger telescope, look for the darker dust lane that crosses through the northeast section.
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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/m002.html |
| Actual Brightness | -- | |
| Number of Stars | -- | |
| Diameter | 2002-08-14 | http://messier.seds.org/m/m002.html |
| Age | 2002-08-14 | basic info |
| Integrated Spectral Type | 2002-11-22 | SIMBAD |
| Other | 2002-08-14 | http://messier.seds.org/m/m002.html 2018-11-26 - https://www.messier-objects.com/messier-2/ |