L1188: a promising candidate of cloud-cloud collision triggering the
  formation of the low- and intermediate-mass stars
  We present a new large-scale (4 square degrees) simultaneous $^{12}$CO,
$^{13}$CO, and C$^{18}$O ($J$=1$-$0) mapping of L1188 with the PMO 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 which exhibits high excitation temperatures, enhanced $^{12}$CO and
$^{13}$CO emission, and broad $^{12}$CO 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.
