A Wide-field Kinematic Survey for Tidal Tails around Five Globular Clusters
نویسندگان
چکیده
Using the AAOmega instrument of the Anglo-Australian Telescope, we have obtained mediumresolution near-infrared spectra of 10,500 stars in two-degree fields centered on the galactic globular clusters 47 Tuc, NGC 288, M12, M30 and M55. Radial velocities and equivalent widths of the infrared Ca II triplet lines have been determined to constrain cluster membership, which in turn has been used to study the angular extent of the clusters. From the analysis of 140–1000member stars in each cluster, we do not find extended structures that go beyond the tidal radii. For three cluster we estimate a 1% upper limit of extra-tidal red giant branch stars. We detect systemic rotation in 47 Tuc and M55. Subject headings: globular clusters – Galaxy: kinematics and dynamics – Galaxy: structure – Galaxy: halo
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