We present the survey of 12CO/13CO/C18O (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 12CO, 13CO, and C18O is about 2.59 × 104, 0.85 × 104, and 0.09 × 104 M ⊙, respectively. A large-scale continuous filament extending about 72 pc is revealed from the 13CO 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 to core-forming 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 C18O 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 C18O 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.

We present observations of the J = 1 – 0 transition lines of 12CO, 13CO, and C18O toward the Galactic region of 153.°60 ≤ l ≤ 156.°50 and 1.°85 ≤ b ≤ 3.°50, using the Purple Mountain Observatory 13.7 m millimeter telescope. Based on the 13CO data, one main filament and five subfilaments are found together as a network structure in the velocity interval of [−42.5, −30.0] km s−1. The kinematic distance of this molecular cloud is estimated to be ∼4.5 kpc. The median length, width, excitation temperature, and line mass of these filaments are ∼49 pc, ∼2.9 pc, ∼8.9 K, and ∼39 M ⊙ pc−1, respectively. The velocity structures along these filaments exhibit oscillatory patterns, which are likely caused by the fragmentation or accretion process along these filaments. The maximum accretion rate is estimated to be ∼700 M ⊙ pc−1. A total of ∼162 13CO clumps and ∼103 young stellar objects are identified in this region. Most of the clumps are in gravitationally bound states. Three H ii regions (G154.359+2.606, SH2-211, and SH2-212) are found to be located in the apexes of the filaments. Intense star-forming activity is found along the entire filamentary cloud. The observed results may help us to better understand the link between filaments and massive star formation.