Distances to molecular clouds in the second Galactic quadrant
QING-ZENG YAN, Ji Yang, Yan Sun, Yang Su, Ye Xu, Hongchi Wang, Xin Zhou, Chen Wang
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 < V LSR < 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.