Hubble Space Telescope Imaging of the Ultra-compact High Velocity Cloud AGC 226067: A Stripped Remnant in the Virgo Cluster

Abstract

We analyze the optical counterpart to the ultra-compact high velocity cloud AGC 226067, utilizing imaging taken with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. The color-magnitude diagram of the main body of AGC 226067 reveals an exclusively young stellar population, with an age of similar to 7-50 Myr, and is consistent with a metallicity of [Fe/H] similar to -0.3 as previous work has measured via H II region spectroscopy. Additionally, the color-magnitude diagram is consistent with a distance of D approximate to 17 Mpc, suggesting an association with the Virgo cluster. A secondary stellar system located similar to 1.'6 (similar to 8 kpc) away in projection has a similar stellar population. The lack of an old red giant branch ((sic)5 Gyr) is contrasted with a serendipitously discovered Virgo dwarf in the ACS field of view (Dw J122147+132853), and the total diffuse light from AGC 226067 is consistent with the luminosity function of the resolved similar to 7-50 Myr stellar population. The main body of AGC 226067 has a M-V = -11.3 +/- 0.3, or M-stars = 5.4 +/- 1.3 x 10(4) M-circle dot given the stellar population. We searched 20 deg(2) of imaging data adjacent to AGC. 226067 in the Virgo Cluster, and found two similar stellar systems dominated by a blue stellar population, far from any massive galaxy counterpart-if this population has star-formation properties that are similar to those of. AGC 226067, it implies similar to 0.1Me(circle dot) yr(-1) in Virgo intracluster star formation. Given its unusual stellar population, AGC 226067 is likely a stripped remnant and is plausibly the result of compressed gas from the ram pressure stripped M86 subgroup (similar to 350 kpc away in projection) as it falls into the Virgo Cluster.