M62 is about21.5 kly[3] fromEarth and5.5 kly from theGalactic Center.[2] It is among the ten most massive and luminous globular clusters in theMilky Way, showing an integratedabsolute magnitude of −9.18.[5] It has an estimated mass of1.22×106M☉[6] and a mass-to-light ratio of2.05±0.04 in the core visible light band, theV band.[12] It has a projectedellipticity of 0.01, meaning it is essentially spherical.[13] The density profile of its member stars suggests it has not yet undergonecore collapse.[14] It has a core radius of 1.3 ly (0.39 pc), a half-mass radius of 9.6 ly (2.95 pc), and a half-light radius of 6.0 ly (1.83 pc). The stellar density at the core is5.13 M☉ per cubic parsec.[15] It has atidal radius of 59 ly (18.0 pc).[8]
The cluster shows at least two distinct populations of stars, which most likely represent two separate episodes of star formation. Of themain sequence stars in the cluster,79%±1% are from the first generation and21%±1% 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.[5]
Indications are this is anOosterhoff type I, or "metal-rich" system. A 2010 study identified 245variable stars in the cluster's field, of which 209 areRR Lyrae variables, four areType II Cepheids, 25 arelong period variables, and one is aneclipsing binary. The cluster may prove to be the galaxy's richest in terms of RR Lyrae variables.[16] It has ten binary millisecondpulsars, including one (M62B) that is displaying eclipsing behavior from gas streaming off its companion,[17] and one (M62H) with an orbiting exoplanet about three times the mass of Jupiter.[18] There are multipleX-ray sources, including 50 within the half-mass radius.[14] 47blue 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.[14]
It is hypothesized that this cluster may be host to anintermediate mass black hole (IMBH) – it is considered well-suited for searching for such an object. A brief study, before 2013, of theproper motion of stars within17″ of the core did not require an IMBH to explain. However, simulations can not rule out one with a mass of a few thousandM☉ in M62's core. For example, based uponradial velocity measurements within anarcsecond of the core, Kiselevet al. (2008) made the claim of an IMBH inM15, likewise with mass of(1–9)×103M☉.[12]
^Shapley, Harlow; Sawyer, Helen B. (August 1927), "A Classification of Globular Clusters",Harvard College Observatory Bulletin,849 (849):11–14,Bibcode:1927BHarO.849...11S.
^abOliveira, R. A. P.; Ortolani, S.; Barbuy, B.; Kerber, L. O.; Maia, F. F. S.; Bica, E.; Cassisi, S.; Souza, S. O.; Pérez-Villegas, A. (2022). "Precise distances from OGLE-IV member RR Lyrae stars in six bulge globular clusters".Astronomy & Astrophysics.657: A123.arXiv:2110.13943.Bibcode:2022A&A...657A.123O.doi:10.1051/0004-6361/202141596.S2CID239998638.
^"Messier 62".SEDS Messier Catalog. Retrieved29 April 2022.
^McNamara, Bernard J.; McKeever, Jean (November 2011), "The Dynamical Distance, RR Lyrae Absolute Magnitude, and Age of the Globular Cluster NGC 6266",The Astronomical Journal,142 (5): 4,Bibcode:2011AJ....142..163M,doi:10.1088/0004-6256/142/5/163, 163.
^Baumgardt, H.; Hilker, M. (August 2018), "A catalogue of masses, structural parameters, and velocity dispersion profiles of 112 Milky Way globular clusters",Monthly Notices of the Royal Astronomical Society,478 (2):1520–1557,arXiv:1804.08359,Bibcode:2018MNRAS.478.1520B,doi:10.1093/mnras/sty1057.
^In daily rising of this star, whether in day- or nighttime, it will reach 15° above the due southern horizon, at the 90°−30°−15° parallel thus the45th parallel north, the furthest north for very detailed observation for this object
Frommert, Hartmut; Kronberg, Christine (August 30, 2007),Messier 62, Students for the Exploration and Development of Space (SEDS), retrieved2018-11-29.
