Northern Galactic Molecular Cloud Clumps in Hi-GAL: Dense Gas Map and
  Environmental Trends
  In the quest to understand high-mass star formation, it is necessary to
understand that from which the high-mass stars will form -- the dense molecular
gas clouds and clumps. The Herschel infrared GALactic plane survey (Hi-GAL) is
a comprehensive survey of thermal dust emission that can be used to
characterize the properties and Galactic distribution of molecular gas. We have
analyzed the survey maps within the Galactic longitude range $10^\circ < \ell <
56^\circ$ and have transformed these 2D maps into a 3D dense gas map of the
Galactic plane using distance probability density functions. This range
corresponds to the extent of the Galactic Ring Survey (GRS), which provided the
majority of our line-of-sight velocities, and thus kinematic distances. In this
section of Hi-GAL, we identify 19,886 clumps, out of which 10,124 have, at
minimum, a kinematic distance, and 5,405 have their distances well constrained
through Bayesian techniques. Of those with well-constrained distances, clump
masses tend to decrease with Galactocentric radius, whereas clump radii are
independent of Galactocentric radius.
