M62 is about 21.5kly[3] from Earth and 5.5kly from the Galactic Center.[2] It is among the ten most massive and luminous globular clusters in the Milky Way, showing an integrated absolute magnitude of −9.18.[5] It has an estimated mass of 1.22×106M☉[6] and a mass-to-light ratio of 2.05±0.04 in the core visible light band, the V band.[12] It has a projected ellipticity of 0.01, meaning it is essentially spherical.[13] The density profile of its member stars suggests it has not yet undergone core collapse.[14] It has a core radius of 1.3ly (0.39pc), a half-mass radius of 9.6ly (2.95pc), and a half-light radius of 6.0ly (1.83pc). The stellar density at the core is 5.13M☉ per cubic parsec.[15] It has a tidal radius of 59ly (18.0pc).[8]
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, 79%±1% are from the first generation and 21%±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 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.[16] It has ten binary millisecond pulsars, 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 multiple X-ray sources, including 50 within the half-mass radius.[14] 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.[14]
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 17″ of the core did not require an IMBH to explain. However, simulations can not rule out one with a mass of a few thousand M☉ 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 (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.
1 2 Oliveira, 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. Retrieved 29 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 the 45th parallel north, the furthest north for very detailed observation for this object
Wikimedia Commons has media related to Messier 62.
Frommert, Hartmut; Kronberg, Christine (August 30, 2007), Messier 62, Students for the Exploration and Development of Space (SEDS), retrieved 2018-11-29.
A globular cluster is a spheroidal conglomeration of stars that is bound together by gravity, with a higher concentration of stars towards its center. It can contain anywhere from tens of thousands to many millions of member stars, all orbiting in a stable, compact formation. Globular clusters are similar in form to dwarf spheroidal galaxies, and though globular clusters were long held to be the more luminous of the two, discoveries of outliers had made the distinction between the two less clear by the early 21st century. Their name is derived from Latin globulus. Globular clusters are occasionally known simply as "globulars".
Messier 107 or M107, also known as NGC 6171 or the Crucifix Cluster, is a very loose globular cluster in a very mildly southern part of the sky close to the equator in Ophiuchus, and is the last such object in the Messier Catalogue.
Messier 2 or M2 is a globular cluster in the constellation Aquarius, five degrees north of the star Beta Aquarii. It was discovered by Jean-Dominique Maraldi in 1746, and is one of the largest known globular clusters.
Messier 15 or M15 is a globular cluster in the constellation Pegasus. It was discovered by Jean-Dominique Maraldi in 1746 and included in Charles Messier's catalogue of comet-like objects in 1764. At an estimated 12.5±1.3 billion years old, it is one of the oldest known globular clusters.
Messier 28 or M28, also known as NGC 6626, is a globular cluster of stars in the center-west of Sagittarius. It was discovered by French astronomer Charles Messier in 1764. He briefly described it as a "nebula containing no star... round, seen with difficulty in 31⁄2-foot telescope; Diam 2′."
Messier 53 is a globular cluster in the Coma Berenices constellation. It was discovered by Johann Elert Bode in 1775. M53 is one of the more outlying globular clusters, being about 60,000 light-years (18.4 kpc) light-years away from the Galactic Center, and almost the same distance from the Solar System. The cluster has a core radius (rc) of 2.18 pc, a half-light radius (rh) of 5.84 pc, and a tidal radius (rtr) of 239.9 pc.
Messier 56 is a globular cluster in the constellation Lyra. It was discovered by Charles Messier in 1779. It is angularly found about midway between Albireo and Sulafat. In a good night sky it is tricky to find with large (50–80 mm) binoculars, appearing as a slightly fuzzy star. The cluster can be resolved using a telescope with an aperture of 8 in (20 cm) or larger.
Messier 68 is a globular cluster found in the east south-east of Hydra, away from its precisely equatorial part. It was discovered by Charles Messier in 1780. William Herschel described it as "a beautiful cluster of stars, extremely rich, and so compressed that most of the stars are blended together". His son John noted that it was "all clearly resolved into stars of 12th magnitude, very loose and ragged at the borders".
Messier 69 or M69, also known NGC 6637, and NGC 6634, is a globular cluster in the southern constellation of Sagittarius. It can be found 2.5° to the northeast of the star Epsilon Sagittarii and is dimly visible in 50 mm aperture binoculars. The cluster was discovered by Charles Messier on August 31, 1780, the same night he discovered M70. At the time, he was searching for an object described by Nicolas-Louis de Lacaille in 1751–2 and thought he had rediscovered it, but it is unclear if Lacaille actually described M69.
Messier 70 or M70, also known as NGC 6681, is a globular cluster of stars to be found in the south of Sagittarius. It was discovered by Charles Messier in 1780. The famous comet Hale–Bopp was discovered near this cluster in 1995.
Messier 71 is a globular cluster in the small northern constellation Sagitta. It was discovered by Philippe Loys de Chéseaux in 1745 and included by Charles Messier in his catalog of non-comet-like objects in 1780. It was also noted by Koehler at Dresden around 1775. Messier 71 is also known as NGC 6839 and The Bernardo Star, though this identification is very uncertain.
Messier 75 or M75, also known as NGC 6864, is a giant globular cluster of stars in the southern constellation Sagittarius. It was discovered by Pierre Méchain in 1780 and included in Charles Messier's catalog of comet-like objects that same year.
Messier 92 is a globular cluster of stars in the northern constellation of Hercules.
NGC 6522 is a globular cluster of stars in the southern constellation of Sagittarius. It was discovered by German-British astronomer William Herschel on June 24, 1784. The cluster has an apparent visual magnitude of 8.3 and an angular diameter of 9.4′. It is located at a distance of 25.1 kly (7.7 kpc) from the Sun, and lies in the Milky Way's central bulge, about 2.0 kly (0.6 kpc) from the Galactic Center. The cluster is centered in a region of the sky known as Baade's Window. It is highly impacted by reddening due to interstellar dust and the view is heavily contaminated by field stars, making it more difficult identify members.
NGC 6934 is a globular cluster of stars in the northern constellation of Delphinus, about 52 kilolight-years distant from the Sun. It was discovered by the German-born astronomer William Herschel on 24 September 1785. The cluster is following a highly eccentric orbit through the Milky Way along an orbital plane that is inclined by 73° to the galactic plane. It may share a common dynamic origin with NGC 5466. As of 2018, it has been poorly studied.
NGC 6539, or GCL 85, is a globular cluster of stars in the constellation Serpens. It was discovered by Danish astronomer Theodor Brorsen in 1856. This cluster is visible with a small amateur telescope, having an apparent visual magnitude of 9.6 and an angular size of 6.9″. It is located at a distance of 26.63 kly (8.165 kpc) from the Sun, and 10 kly (3.1 kpc) from the Galactic Center.
NGC 6388 is a globular cluster of stars located in the southern constellation of Scorpius. The cluster was discovered by Scottish astronomer James Dunlop on May 13, 1826 using a 20 cm (9 in) reflector telescope. It was later determined to be a globular cluster by English astronomer John Herschel, who was able to resolve it into individual stars. NGC 6388 is located at a distance of approximately 35,600 light-years (10.90 kpc) from the Sun. Due to its apparent visual magnitude of +6.8, binoculars or a small telescope are required to view it.
NGC 6441, sometimes also known as the Silver Nugget Cluster, is a globular cluster in the southern constellation of Scorpius. It was discovered by the Scottish astronomer James Dunlop on May 13, 1826, who described it as "a small, well-defined rather bright nebula, about 20″ in diameter". The cluster is located 5 arc minutes east-northeast of the star G Scorpii, and is some 43,000 light-years from the Sun.
NGC 6440 is a globular cluster of stars in the southern constellation of Sagittarius. It was discovered by German-English astronomer William Herschel on 28 May 1786. With an apparent visual magnitude of 9.3 and an angular diameter of 4.4′, it can be observed as a fuzzy blob when viewed through a small telescope. Its Shapley–Sawyer Concentration Class is V.
NGC 6535 is a globular cluster of stars located at a distance of 22,200 light years from Earth in the equatorial constellation of Serpens, and is listed in the New General Catalogue. Its discovery is usually attributed to astronomer John Russell Hind in 1852. However, Wolfgang Steinicke has uncovered evidence that William Herschel's first discovery was actually NGC 6535, which he observed on 24 August 1780.
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