AGC 226067: A possible interacting low-mass system

¹ ASTRON, Netherlands Institute for Radio Astronomy, Postbus 2, 7900 AA Dwingeloo, The Netherlands
e-mail: adams@astron.nl
² Department of Physics and Astronomy, Macalaster College, 1600 Grand Avenue, Saint Paul, MN 55105, USA
³ Department of Astronomy, Indiana University, 727 East Third Street, Bloomington, IN 47405, USA
⁴ Center for Radiophysics and Space Research, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA

Received: 30 June 2015
Accepted: 7 July 2015

Abstract

We present Arecibo, GBT, VLA, and WIYN/pODI observations of the ALFALFA source AGC 226067. Originally identified as an ultra-compact high velocity cloud and candidate Local Group galaxy, AGC 226067 is spatially and kinematically coincident with the Virgo cluster, and the identification by multiple groups of an optical counterpart with no resolved stars supports the interpretation that this systems lies at the Virgo distance (D = 17 Mpc). The combined observations reveal that the system consists of multiple components: a central H i source associated with the optical counterpart (AGC 226067), a smaller H i-only component (AGC 229490), a second optical component (AGC 229491), and extended low-surface brightness H i. Only ~1/4 of the single-dish H i emission is associated with AGC 226067; as a result, we find M_HI/L_g ~ 6M_⊙/L_⊙  which is lower than previous work. At D = 17 Mpc, AGC 226067 has an H i mass of 1.5 × 10⁷M_⊙ and L_g = 2.4 × 10⁶L_⊙, AGC 229490 (the H i-only component) has M_HI = 3.6 × 10⁶M_⊙, and AGC 229491 (the second optical component) has L_g = 3.6 × 10⁵L_⊙. The nature of this system of three sources is uncertain: AGC 226067 and AGC 229490 may be connected by an H i bridge, and AGC 229490 and AGC 229491 are separated by only 0.5′. The current data do not resolve the H i in AGC 229490 and its origin is unclear. We discuss possible scenarios for this system of objects: an interacting system of dwarf galaxies, accretion of material onto AGC 226067, or stripping of material from AGC 226067.