Messier 30
| Messier 30 | |
|---|---|
 M30 by Hubble Space Telescope; 3.5′ view Credit: NASA/STScI/WikiSky |
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| Observation data (J2000 epoch) | |
| Class | V |
| Constellation | Capricornus |
| Right ascension | 21h 40m 22.03s[1] |
| Declination | –23° 10′ 44.6″[1] |
| Distance | 29.4 ± 1.6 kly (9.0 ± 0.5 kpc[2]) |
| Apparent magnitude (V) | +7.7[1] |
| Physical characteristics | |
| Mass | 1.6 × 105[3] M☉ |
| Estimated age | 12.93 Gyr[4] |
| Other designations | M30, NGC 7099, GCl 122[1] |
| See also: Globular cluster, List of globular clusters | |
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Wikimedia Commons has media related to: Messier 30 |
Messier 30 (also known as M30 or NGC 7099) is a globular cluster of stars in the southern constellation of Capricornus. It was discovered by the French astronomer Charles Messier in 1764, who described it as a circular nebula without a star. In the New General Catalogue, compiled during the 1880s, it was described as a "remarkable globular, bright, large, slightly oval." This cluster can be easily viewed with a pair of 10×50 binoculars,[5] forming a patch of hazy light some 4 arcminutes wide that is slightly elongated along the east-west axis.[5] With a larger instrument, individual stars can be resolved and the cluster will cover an angle of up to 12 arcminutes across with a compressed core one arcminute wide.[6] It is best observed around August.[5]
M30 is located at a distance of about 29,400 light-years from Earth,[2] and is about 93 light-years across.[6] The estimated age is roughly 12.93 billion years[4] and it has a combined mass of about 160,000 times the mass of the Sun.[3] The cluster is following a retrograde orbit through the inner galactic halo, suggesting that it was acquired from a satellite galaxy rather than forming within the Milky Way.[4] It is currently located at a distance of about 22.2 kly (6.8 kpc) from the center of the galaxy, compared to an estimated 26 kly (8.0 kpc) for the Sun.[7]
The M30 cluster has passed through a dynamic process called core collapse and now has a concentration of mass at its core of about a million times the Sun's mass per cubic parsec. This makes it one of the highest density regions in the Milky Way galaxy. Stars in such close proximity will experience a high rate of interactions that can create binary star systems, as well as a type of star called a blue straggler that is formed by mass transfer.[2] A process of mass segregation may have caused the central region to gain a greater proportion of higher mass stars, creating a color gradient with increasing blueness toward the middle of the cluster.[8]
[edit] References
- ^ a b c d "NGC 7099", SIMBAD Astronomical Database (Centre de Données astronomiques de Strasbourg), http://simbad.u-strasbg.fr/Simbad, retrieved 2006-11-16
- ^ a b c Lugger, Phyllis M. et al. (March 2007), "Chandra X-Ray Sources in the Collapsed-Core Globular Cluster M30 (NGC 7099)", The Astrophysical Journal 657 (1): 286–301, Bibcode 2007ApJ...657..286L, doi:10.1086/507572
- ^ a b Vande Putte, D.; Cropper, Mark (January 2009), "Detecting the effect of globular cluster impacts on the disc of the Milky Way", Monthly Notices of the Royal Astronomical Society 392 (1): 113–124, Bibcode 2009MNRAS.392..113V, doi:10.1111/j.1365-2966.2008.14072.x
- ^ a b c Forbes, Duncan A.; Bridges, Terry (May 2010), "Accreted versus in situ Milky Way globular clusters", Monthly Notices of the Royal Astronomical Society 404 (3): 1203–1214, Bibcode 2010MNRAS.404.1203F, doi:10.1111/j.1365-2966.2010.16373.x
- ^ a b c Bone, N. M. (August 2008), "Sky notes, 2008 August & September", Journal of the British Astronomical Association 118 (4): 231-232, Bibcode 2008JBAA..118..231B
- ^ a b O'Meara, Stephen James (1998), The Messier objects, Deep-sky companions, Cambridge University Press, p. 108, ISBN 0521553326, http://books.google.com/books?id=jis4evHuuzUC&pg=PA108
- ^ Dinescu, Dana I. et al. (January 1999), "Space Velocities of Southern Globular Clusters. II. New Results for 10 Clusters", The Astronomical Journal 117 (1): 277–285, Bibcode 1999AJ....117..277D, doi:10.1086/300699
- ^ Howell, Justin H.; Guhathakurta, Puragra; Tan, Amy (March 2000), "Radial Color Gradient and Main-Sequence Mass Segregation in M30 (NGC 7099)", The Astronomical Journal 119 (3): 1259–1267, Bibcode 2000AJ....119.1259H, doi:10.1086/301270
[edit] External links
- Globular Cluster M30 @ SEDS Messier pages
- Messier 30, Galactic Globular Clusters Database page
- Messier 30 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
Coordinates: 
21h 40m 22.03s, −23° 10′ 44.6″
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