Identifying Nearby Molecular Clouds

摘要

Recent molecular surveys, such as the BU-FCRAO Galactic Ring Survey, are revealing the complex structure and dynamics of clouds within the Galactic plane. Yet, difficulties often remain in separating molecular clouds along a line of sight. Identification of nearby clouds is facilitated through the combination of molecular datasets and extinction maps. Star counts at optical and infrared (IR) wavelengths indirectly trace extinction, and when morphologically similar to molecular emission, unambiguously reveal nearby clouds. Here we present the methodology and data used to separate and determine the relative distance to two molecular clouds along the same line of sight (GRSMC 45.60+0.30, and GRSMC 45.46+0.05). We use a combination of optical and near-IR star count maps (derived from the US Naval Observatory and 2MASS catalogs, respectively) and molecular data from the BU-FCRAO Galactic Ring Survey.