Updated Inventory of Carbon Monoxide in The Taurus Molecular Cloud

Abstract

The most extensive survey of carbon monoxide (CO) gas in the Taurus molecular cloud relied on ${}^{12}$CO and ${}^{13}$CO $J=1\to 0$ emission only, distinguishing the region where ${}^{12}$CO is detected without ${}^{13}$CO (named mask 1 region) from the one where both are detected (mask 2 region). We have taken advantage of recent ${}^{12}$CO $J=3\to 2$ JCMT observations where they include mask 1 regions to estimate density, temperature, and $N$(CO) with a LVG model. This represents 1395 pixels out of $\sim$1.2 million in the mark 1 region. Compared to Pineda et al. (2010) results, and assuming a $T_{\text{kin}}$ of 30 K, we find a higher volume density of molecular hydrogen of 3.3$\times 10^3$ ${\text{cm}}^{-3}$, compared to their 250-700 ${\text{cm}}^{-3}$ and a CO column density of 5.7$\times 10^{15}{\text{cm}}^{-2}$, about a quarter of their value. The differences are important and show the necessity to observe several CO transitions to better describe the intermediate region between the dense cloud and the diffuse atomic medium. Future observations to extend the ${}^{12}$CO $J=3\to 2$ mapping further away from the ${}^{13}$CO-detected region comprising mask 1 are needed to revisit our understanding of the diffuse portions of dark clouds.

Accepted for publication in Research in Astronomy and Astrophysics. 18 pages, 2 tables, 8 figures

References in corpus (4)

• The relation between gas and dust in the Taurus Molecular Cloud
• The James Clerk Maxwell Telescope Legacy Survey of Nearby Star-forming Regions in the Gould Belt
• The Five College Radio Astronomy Observatory CO Mapping Survey of the Taurus Molecular Cloud
• Discovery of a New Molecular Bubble-Outflow Structure in the Taurus B18 Cloud