It is easily found in the sky, being close to the starζ Sagittarii. It is, however, not resolvable into individual stars even with larger amateur telescopes.
In July 2009, a team of astronomers reported that they had found evidence of an intermediate-mass black hole in the core of M54.[8]
Distance
Previously thought to belong to the
Sagittarius Dwarf Elliptical Galaxy (SagDEG),[9] making it the first globular cluster formerly thought to be part of our galaxy reassigned to extragalactic status, even if not recognized as such for more than two centuries. As it is located in SagDEG's center, some authors think it actually may be its core;[10] however others have proposed that it is a real globular cluster that fell to the center of this galaxy due to decay of its orbit caused by dynamical friction.[11]
Modern estimates now place M54 at a distance of some 87,000 light-years,
class III[1] (I being densest and XII being the least dense). It shines with the luminosity of roughly 850,000 times that of the Sun and has an absolute magnitude of −10.0.
^
Geisler, Doug; Wallerstein, George; Smith, Verne V.; Casetti-Dinescu, Dana I. (2007). "Chemical Abundances and Kinematics in Globular Clusters and Local Group Dwarf Galaxies and Their Implications for Formation Theories of the Galactic Halo".
^
Ibata, R.; Bellazzini, M.; Chapman, S. C.; Dalessandro, E.; et al. (2009). "Density and Kinematic Cusps in M54 at the Heart of the Sagittarius Dwarf Galaxy: Evidence for a 104M☉ Black Hole?".
^
Siegel, Michael H.; Dotter, Aaron; Majewski, Steven R.; Sarajedini, Ata; et al. (2007). "The ACS Survey of Galactic Globular Clusters: M54 and Young Populations in the Sagittarius Dwarf Spheroidal Galaxy".
^Specifically in centre this very mildly southern zone of the sky which is well observable from everywhere except the Arctic Circle. However the Sun, considered from our orbit, passes through this zone throughout December. This also makes the cluster mostly risen during day, not night, in the nearest months.
External links
Wikimedia Commons has media related to Messier 54.