NGC 5053 is the New General Catalogue designation for a globular cluster in the northern constellation of Coma Berenices. It was discovered by German-British astronomer William Herschel on March 14, 1784 and cataloged as VI-7. In his abbreviated notation, he described it as, "an extremely faint cluster of extremely small stars with resolvable nebula 8 or 10′ diameter, verified by a power of 240, beyond doubt".[5] Danish-Irish astronomer John Louis Emil Dreyer reported in 1888 that the cluster appeared, "very faint, pretty large, irregular round shape, growing very gradually brighter at the middle".[6]
This is a metal-poor cluster, meaning the stars have a low abundance of elements other than hydrogen and helium—what astronomers term metallicity. As recently as 1995, it was considered the most metal-poor globular cluster in the Milky Way.[7] The chemical abundances of the stars in NGC 5053 are more similar to those in the dwarf galaxy Sagittarius Dwarf Spheroidal Galaxy than to the Milky Way halo. Along with the kinematics of the globular cluster, this suggests that NGC 5053 may have been stripped from the dwarf galaxy.[8]
NGC 5053 is a relatively low mass cluster with a low core concentration factor of 1.32. It sports a stream of tidal debris to the west with a projected length of 1.7 kpc. This stream may have been created through shock-induced processes.[10] The cluster is located less than 1° from Messier 53 and the two have nearly the same distance modulus, which corresponds to a spatial separation of around 2 kpc. There is a tidal bridge joining M53 to NGC 5053, suggesting the pair may have interacted in the past.[2] The cluster is following an orbit through the Milky Way that has a perigalacticon distance of 9 kpc and an orbital eccentricity of 0.84.[10] At present, it is 18.4 kpc from the Galactic Center, with a radial velocity of 42.0±1.4 km/s.[2]
^Sarajedini, Ata; Milone, Alejandra A. E. (January 1995), "BVI CCD photometry of NGC 5053: The most metal-poor galactic globular cluster", The Astronomical Journal, 109 (1669): 269–279, Bibcode:1995AJ....109..269S, doi:10.1086/117271.
^ abNemec, James M. (April 2004), "Physical Characteristics of the RR Lyrae Stars in the Very Metal Poor Globular Cluster NGC 5053", The Astronomical Journal, 127 (4): 2185–2209, Bibcode:2004AJ....127.2185N, doi:10.1086/382903.
^ abLauchner, Adam; et al. (November 2006), "Discovery of a Tidal Stream Extending from NGC 5053", The Astrophysical Journal, 651 (1): L33 –L36, Bibcode:2006ApJ...651L..33L, doi:10.1086/509254.
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