Distances to molecular clouds in the second Galactic quadrant

Abstract

We present distances to 76 medium-sized molecular clouds and an extra large-scale molecular cloud in the second Galactic quadrant (104. °75 < l < 150. °25 and |b| < 5. °25), 73 of which are accurately measured for the first time. Molecular cloud samples are drawn from l-b-V space (- 95 < VLSR < 25 km s-1) with the density-based spatial clustering of applications with noise algorithm, and distances are measured with the background-eliminated extinction-parallax method using extinctions and Gaia DR2 parallaxes. The range of the measured distances to the 76 molecular clouds is from 211 to 2631 pc, and the extra large-scale molecular cloud appears to be a coherent structure at about 1 kpc, across about 40° (∼700 pc) in the Galactic longitude.