2007/07/01 by Brian R. Kent, Kent, Brian R., Riccardo Giovanelli +19 · 2 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #FOS: Physical sciences #Gamma-ray bursts and supernovae #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.0707.0109
openalex publication_date 2007/07/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We report the discovery by the Arecibo Legacy Fast ALFA (ALFALFA) survey of eight HI features not coincident with stellar counterparts in the Virgo Cluster region. All of the HI clouds have cz < 3000 km/s and, if at the Virgo distance, HI masses between 1.9 x 10**7 and 1.1 x 10**9 solar masses. Four of the eight objects were reported or hinted at by previous studies and "rediscovered" by ALFALFA. While some clouds appear to be associated with optical galaxies in their vicinity, others show no clear association with a stellar counterpart. Two of them are embedded in relatively dense regions of the cluster and are associated with M49 and M86; they were previously known. The others are mostly located in peripheral regions of the cluster. Especially notable are a concentration of objects towards the so-called M cloud, 3 to 5 degrees to the NW of M87, and a complex of several clouds projected roughly halfway between M87 and M49. The object referred to as VIRGOHI21 and proposed to be a "dark galaxy" is also detected and shown to be a tidal feature associated with NGC 4254.