Presentation #430.02 in the session “Spiral Galaxies”.
We report the discovery of four kinematically anomalous atomic hydrogen clouds (AHCs) in M100 (NGC4321) through high spectral resolution HI 21 cm imaging with the Karl G. Jansky Very Large Array (VLA) of the National Radio Astronomy Observatory (NRAO). We identify these gas clouds by their velocity offsets that range between 40 and 220 km/s from the rotating HI disk of the galaxy. The AHCs in M100 are analogous to the high- and intermediate-velocity clouds observed in the Milky Way and nearby galaxies in terms of velocity offset, HI mass, size, and line width. We compare different models and conclude that these clouds are more likely to be explained by the galactic fountain model.