A wide-field CO survey towards the California Molecular Filament

Abstract

We present the survey of 12 CO/ 13 CO/C 18 O (J=1-0) toward the California Molecular Cloud (CMC) within the region of 161.75 • l 167.75 • , -9.5 • b -7.5 • , using the Purple Mountain Observatory (PMO) 13.7 m millimeter telescope. Adopting a distance of 470 pc, the mass of the observed molecular cloud estimated from 12 CO, 13 CO, and C 18 O is about 2.59×10 4 M ⊙ , 0.85×10 4 M ⊙ , and 0.09×10 4 M ⊙ , respectively. A large-scale continuous filament extending about 72 pc is revealed from the 13 CO images. A systematic velocity gradient perpendicular to the major axis appears and is measured to be ∼ 0.82 km s −1 pc −1 . The kinematics along the filament shows an oscillation pattern with a fragmentation wavelength of ∼ 2.3 pc and velocity amplitude of ∼ 0.92 km s −1 , which may be related with coreforming flows. Furthermore, assuming an inclination angle to the plane of the sky of 45 • , the estimated average accretion rate is ∼ 101 M ⊙ Myr −1 for the cluster LkHα 101 and ∼ 21 M ⊙ Myr −1 for the other regions. In the C 18 O observations, the large-scale filament could be resolved into multiple substructures and their dynamics are consistent with the scenario of filament formation from converging flows. Approximately 225 C 18 O cores are extracted, of which 181 are starless cores. Roughly 37 % (67/181) of the starless cores have α vir less than 1. Twenty outflow candidates are identified along the filament. Our results indicate active early-phase star formation along the large-scale filament in the CMC region.