Messier 62

Messier 62 or M62, also known as NGC 6266 or the Flickering Globular Cluster, is a globular cluster of stars in the southTemplate:Efn of the equatorial constellation of Ophiuchus. It was discovered in 1771 by Charles Messier,Template:Efn then added to his catalogue eight years later.

M62 is about from Earth and from the Galactic Center. It is among the ten most massive and luminous globular clusters in the Milky Way, showing an integrated absolute magnitude of −9.18. It has an estimated mass of and a mass-to-light ratio of in the core visible light band, the V band. It has a projected ellipticity of 0.01, meaning it is essentially spherical. The density profile of its member stars suggests it has not yet undergone core collapse. It has a core radius of , a half-mass radius of , and a half-light radius of . The stellar density at the core is per cubic parsec. It has a tidal radius of .

The cluster shows at least two distinct populations of stars, which most likely represent two separate episodes of star formation. Of the main sequence stars in the cluster, are from the first generation and from the second. The second is enriched by elements released by the first. In particular, abundances of helium, carbon, magnesium, aluminium, and sodium differ between these two.

Indications are this is an Oosterhoff type I, or "metal-rich" system. A 2010 study identified 245 variable stars in the cluster's field, of which 209 are RR Lyrae variables, four are Type II Cepheids, 25 are long period variables, and one is an eclipsing binary. The cluster may prove to be the galaxy's richest in terms of RR Lyrae variables. It has ten binary millisecond pulsars, including one (M62B) that is displaying eclipsing behavior from gas streaming off its companion, and one (M62H) with an orbiting exoplanet about three times the mass of Jupiter. There are multiple X-ray sources, including 50 within the half-mass radius. 47 blue straggler candidates have been identified, formed from the merger of two stars in a binary system, and these are preferentially concentrated near the core region.

It is hypothesized that this cluster may be host to an intermediate mass black hole (IMBH) – it is considered well-suited for searching for such an object. A brief study, before 2013, of the proper motion of stars within of the core did not require an IMBH to explain. However, simulations can not rule out one with a mass of a few thousand Template:Solar mass in M62's core. For example, based upon radial velocity measurements within an arcsecond of the core, Kiselev et al. (2008) made the claim of an IMBH in M15, likewise with mass of .

Gallery

• Messier 62 by the Hubble Space Telescope; Script error: No such module "val". field of view
  Messier 62 by the Hubble Space Telescope; field of view
• Globular Cluster M62 - wide field view
  Globular Cluster M62 - wide field view
• Map showing the location of M62.
  Map showing the location of M62.

See also

• List of Messier objects

References and footnotes

Template:Notelist

External links

• Messier 62, Galactic Globular Clusters Database page
• M62 on willig.net
• Template:WikiSky