Three isotopologues CO survey of Molecular Clouds in the CMa OB1 complex

TL;DR

This study conducted a large-scale survey of three CO isotopologues in the CMa OB1 molecular cloud complex, revealing its structure, physical properties, and star formation activity, including new outflow candidates and insights into cloud evolution.

Contribution

It provides the first comprehensive, multi-isotopologue CO survey of CMa OB1, identifying molecular clumps and outflows, and analyzing their physical and evolutionary characteristics.

Findings

94% of C18O clumps are gravitationally bound

Identified 85 CO outflow candidates, including 23 bipolar outflows

Variety in physical properties and star formation activity across sub-regions

Abstract

Using the Purple Mountain Observatory 13.7-m millimeter telescope at Delingha in China, we have conducted a large-scale simultaneous survey of $^{12}$CO, $^{13}$CO, and \xxco ($J$ = 1--0) toward the CMa OB1 complex with a sky coverage of 16.5 deg$^{\rm 2}$ ($221^{\circ}.5\leq l\leq227^{\circ}$, $-2^{\circ}.5\leq b\leq0^{\circ}.5$). Emission from the CMa OB1 complex is found in the range 7 km s$^{-1}\ \leq$ V$_\mathrm{LSR}\ \leq$ 25 km s$^{-1}$. The large-scale structure, physical properties and chemical abundances of the molecular clouds are presented. A total of 83 C$^{18}$O molecular clumps are identified with GaussClumps algorithm within the mapped region. We find that 94% of these C$^{18}$O molecular clumps are gravitationally bound. The relationship between their size and mass indicates that none of the C$^{18}$O clump has the potential to form high-mass stars. Using semi-automatic IDL algorithm, we newly discover 85 CO outflow candidates in the mapped area, including 23 bipolar outflows candidates. Additionally, a comparative study reveals evidence for significant variety of physical properties, evolutionary stages, and levels of star formation activity in different sub-regions of the CMa OB1 complex.