Dust-to-gas ratios of the GALFA-H I compact cloud catalog

Abstract

We have searched for infrared dust emission from subsets of compact, Galactic neutral hydrogen clouds, with the purpose of looking for dust in high-velocity clouds, identifying low-velocity halo clouds, and investigating the cloud populations defined in the GALFA-H I Compact Cloud Catalog. We do not detect dust emission from high-velocity clouds. The lack of dust emission from a group of low-velocity clouds supports the claim that they are low-velocity halo clouds. We detect dust in the remaining low-velocity clouds, indicating a Galactic origin, with a significantly greater dust-to-gas ratio for clouds with linewidths near 15 km s-1. We propose that this is due to dust associated with ionized gas. © 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.