AAS 207th Meeting, 8-12 January 2006
Session 187 Radio Astronomy Legacy Sky Surveys with ALFA
Poster, Thursday, 9:20am-4:00pm, January 12, 2006, Exhibit Hall

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[187.03] ALFALFA Survey of the Leo Region

S. Stierwalt, M.P. Haynes, R. Giovanelli, B. Kent, A. Saintonge (Cornell University), I.D. Karachentsev (Russian Academy of Sciences), V.E. Karachentseva (Astronomical Observatory of Kiev), N. Brosch (Wise Observatory), B. Catinella (Arecibo Observatory), L. Hoffman (Lafayette College), E. Momjian (Arecibo Observatory)

The Leo region offers a detailed view of several nearby groups of galaxies including Leo I at 10.4 Mpc and another slightly more distant structure within the Local Supercluster (Leo II). Leo I is of particular interest because it contains both a large ring of intergalactic gas of unknown origin (the Leo Ring) as well as a long tidal stream of stars and gas in the Leo Triplet. Because of its proximity, Leo can also offer insight into the nature of low-mass, low-surface brightness galaxies believed to be the building blocks of galaxy formation. A catalog of HI line detections in the Leo region (10h30m < RA < 11h30m and +8o < dec < +16o) has been made using data from the blind HI survey ALFALFA which takes advantage of the new, multi-feed array on the 305-m Arecibo telescope. The ALFALFA detections have been cross-referenced with optical catalogs and combined with targetted, single-pixel Arecibo observations of galaxies in the same area of the sky. The more sensitive observations targetted possible Leo Group candidates noted by Karachentsev and Karachentseva through a visual inspection of POSS-II/ESO/SERC plates. Twenty-one of a possible thirty-five dwarf galaxy candidates were detected in HI including five background sources. Structure of the group and possible trends between characteristics like morphological class, HI mass, and distance from the group center will be discussed. Combining the ALFALFA data with the targetted, single-pixel observations allows for a direct comparison of optically and HI selected samples. This work has been supported by NSF grants AST--0307661 and AST--0435697 and by the Brinson Foundation.

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