Properties of Two Intergalactic Globular Clusters.

Abstract

view Abstract Citations (68) References (11) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Properties of Two Intergalactic Globular Clusters. Burbidge, E. Margaret ; Sandage, Allan Abstract Data for two very distant globular clusters are given. The 1 1h cluster at R.A. (1950) = 1 Dec. (1950) = + ', has an apparent distance of 1.2 X 10 pc if Mis 0.00 for the horizontal branch. has a diameter of about 90 pc, an integrated absolute magnitude M, = -63, an estimated mass of 1.8 X 10 O, and an estimated total number of stars of 4.3 X 10 . The 10h cluster at R.A. (1950) = Dec. (1950) = + ' has an apparent distance of 1.3 X 10' pc, a diameter of about 80 pc, an integrated M,, of -5.9, an estimated mass of 1.1 X 10 O, and an estimated total number of stars of 2.7 x 10 . The diameters of both clusters are unusually large compared with systems like M3 and Ml3, which are more populous by factors of at least 10. Large diameters are expected if the tidal force of the Galaxy, which limits the radii of most clusters, has always been small. The observed diameters can be explained if the two clusters have never passed closer than 9000 pc to the galactic center. This result requires that the clusters were formed at least 9000 pc from the galactic center. The 1O and 11h clusters could reach their present distances in about 10 years if they are moving in parabolic orbits around the galactic center. If the clusters are escaped members of M31, they could reach their present position in about lOlO years if the clusters have the escape velocity and if we neglect the influence of the Galaxy. The true travel time from M31 will be less than 1010 years because of the attraction of the galactic system. Computation of the correct travel time from M3 1 is given the restricted three-body problem, which is not discussed. Publication: The Astrophysical Journal Pub Date: May 1958 DOI: 10.1086/146484 Bibcode: 1958ApJ...127..527B full text sources ADS | data products SIMBAD (5)