A peculiar H i cloud near the distant globular cluster Pal 4 |
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Authors: | Jacco Th. van Loon,Sne ana Stanimirovi ,Mary E. Putman,Joshua E. G. Peek,Steven J. Gibson,Kevin A. Douglas, Eric J. Korpela |
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Affiliation: | Astrophysics Group, Lennard-Jones Laboratories, Keele University, Staffordshire ST5 5BG;Department of Astronomy, University of Wisconsin, Madison, WI 53706, USA;Department of Astronomy, Columbia University, New York, NY 10027, USA;Department of Astronomy, UC Berkeley, 601 Campbell Hall, Berkeley, CA 94720, USA;Department of Physics and Astronomy, Western Kentucky University, Bowling Green, KY 42101, USA;Astrophysics Group, School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL;Space Sciences Laboratory, UC Berkeley, 601 Campbell Hall, Berkeley, CA 94720, USA |
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Abstract: | We present 21-cm observations of four Galactic globular clusters, as part of the on-going Galactic Arecibo L-band Feed Array (GALFA) H i survey at Arecibo. We discovered a peculiar H i cloud in the vicinity of the distant (109 kpc) cluster Pal 4, and discuss its properties and likelihood of association with the cluster. We conclude that an association of the H i cloud and Pal 4 is possible, but that a chance coincidence between Pal 4 and a nearby compact high-velocity cloud cannot be ruled out altogether. New, more stringent upper limits were derived for the other three clusters: M 3, NGC 5466, and Pal 13. We briefly discuss the fate of globular cluster gas and the interaction of compact clouds with the Galactic halo gas. |
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Keywords: | ISM: clouds globular clusters: individual: Pal 4 Galaxy: halo galaxies: dwarf dark matter radio lines: ISM |
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