AAS 207th Meeting, 8-12 January 2006
Session 179 Evolution of Galaxies, and Galaxies Surveys at Low Redshift
Poster, Thursday, 9:20am-4:00pm, January 12, 2006, Exhibit Hall

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[179.25] ALFALFA Discovery of an HI Cloud Complex in the Virgo Cluster: Aperture Synthesis Observations

K. Spekkens (NRAO/Rutgers University), E. Momjian (NAIC/Arecibo Observatory), B. R. Kent, R. Giovanelli, M. P. Haynes (Cornell University), B. Catinella (NAIC/Arecibo Observatory), S. Stierwalt, A. Saintonge (Cornell University)

We present aperture synthesis observations of the HI cloud complex in Virgo detected by the Arecibo Legacy Fast ALFA Survey (ALFALFA, Giovanelli et al. 2005 AJ in press and astro-ph/0508301), which are shown in a companion poster by Giovanelli et al. (2006). C-configuration Very Large Array (VLA) observations were obtained in the vicinity of the center of the complex, and are sensitive to 4 x 106 solar masses at the Virgo distance on spatial scales accessible to the VLA. We make two faint but definitive detections in the resulting data: the first is associated with the largest cloud in the complex, while the second coincides with an ALFALFA source near the LSB galaxy VCC 1357. In both cases, the ALFALFA clouds resolve into a network of HI clumps exhibiting no ordered velocity structure. The field of view of the VLA observations does not include the totality of the cloud complex, which extends over more than 40'. As a result, the total flux of the Arecibo observations is not recovered by the interferometric data. However, most of the central cloud Arecibo flux appears to be detected by the VLA. The aperture synthesis observations also show that the centroid of the secondary HI cloud apparently associated with VCC 1357 is displaced by 1.4' (6.5 kpc in projection at a distance of 16 Mpc) from the optical centroid of the latter. An interpretation of the observations in terms of a galaxy harassment scenario in the Virgo cluster potential is favored. This research is partially supported by NSF/AST-0307661, NSF/AST-0435697 and a Brinson Foundation grant.

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The author(s) of this abstract have provided an email address for comments about the abstract: spekkens@physics.rutgers.edu

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