L1188: A Promising Candidate for Cloud-Cloud Collisions Triggering the Formation of Low-and Intermediate-mass Stars

摘要

We present a new large-scale (2 degrees x 2 degrees) simultaneous (CO)-C-12, (CO)-C-13, and (CO)-O-18 (J = 1-0) mapping of L1188 with the Purple Mountain Observatory 13.7 m telescope. Our observations have revealed that L1188 consists of two nearly orthogonal filamentary molecular clouds at two clearly separated velocities. Toward the intersection showing large velocity spreads, we find several bridging features connecting the two clouds in velocity, and an open arc structure that exhibits high excitation temperatures, enhanced (CO)-C-12 and (CO)-C-13 emission, and broad (CO)-C-12 line wings. This agrees with the scenario that the two clouds are colliding with each other. The distribution of young stellar object (YSO) candidates implies an enhancement of star formation in the intersection of the two clouds. We suggest that a cloud-cloud collision happened in L1188 about 1 Myr ago, possibly triggering the formation of low-and intermediate-mass YSOs in the intersection.