Messier Index/M54

Messier 54 250px M54 by w:Hubble Space Telescope; 3.5′ view w:NASA/w:STScI/w:WikiSky w:J2000 III Sagittarius 18 55 03.28SIMBAD Astronomical Database Results for NGC 6715 http://simbad.u-strasbg.fr/Simbad 2006-11-16 -30 28 42.6 87.4 klyGavin Ramsay and Kinwah Wu, Chandra observations of the globular cluster M54 26.8 kpc 8.37 12′.0 153 lydistance × sin( diameter_angle / 2 ) = 153 ly. radius 13 Gyr Geisler Doug Wallerstein George Smith Verne V. Casetti-Dinescu Dana I. Chemical Abundances and Kinematics in Globular Clusters and Local Group Dwarf Galaxies and Their Implications for Formation Theories of the Galactic Halo 2007 September 2007 The Publications of the Astronomical Society of the Pacific 119 859 939-961 http://adsabs.harvard.edu/abs/2007PASP..119..939G 10.1086/521990 Probably extragalactic M54, NGC 6715, GCl 104 Messier 54 Messier 54 (also known as M54 or NGC 6715) is a w:globular cluster in the w:constellation Sagittarius. It was discovered by w:Charles Messier in w:1778 and subsequently included in his catalog of w:comet-like objects. Previously thought to be at a distance from w:Earth of about 50,000 w:light-years, it was discovered in w:1994 that M54 was most likely not part of the w:Milky Way, but actually part of the w:Sagittarius Dwarf Elliptical Galaxy, (SagDEG), Siegel Michael H. Dotter Aaron Majewski Steven R. Sarajedini Ata Chaboyer Brian Nidever David L. Anderson Jay Marín-Franch Antonio Rosenberg Alfred Bedin Luigi R. Aparicio Antonio King Ivan Piotto Giampaolo Reid I. Neill The ACS Survey of Galactic Globular Clusters: M54 and Young Populations in the Sagittarius Dwarf Spheroidal Galaxy http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2007ApJ...667L..57S 2007 September 2007 The Astrophysical Journal 667 1 L57-L60 10.1086/522003 making it the first extragalactic globular cluster ever discovered, even if it wasn't recognized as such for nearly two and a quarter centuries. Modern estimates now place M54 at a distance of some 87,000 light-years, translating into a true radius of 150 light-years across. It is one of the denser of the globulars, being of class III (I being densest and XII being the least dense). It shines with the w:luminosity of roughly 850,000 times that of the w:Sun and has an w:absolute magnitude of -10.0. M54 is easily found on the sky, being close to the w:star ζ Sagittarii. It is however, not resolvable into individual stars even with larger amateur w:telescopes. In July of 2009, a team of astronomers reported that they had found evidence of an w:intermediate-mass black hole in the core of M54. Ibata R. Bellazzini M. Chapman S. C. Dalessandro E. Ferraro F. Irwin M. Lanzoni B. Lewis G. F. Mackey A. D. Miocchi P. Varghese A. Density and Kinematic Cusps in M54 at the Heart of the Sagittarius Dwarf Galaxy: Evidence for A Black Hole? 2009 July 2009 The Astrophysical Journal Letters 699 2 L169-L173 http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:0906.4894 10.1088/0004-637X/699/2/L169 This was the first report of such a black hole in any globular cluster. External links M54 @ SEDS Messier pages References