New insights in giant molecular cloud hosting S147/S153 complex:
  signatures of interacting clouds
  In order to understand the formation of massive OB stars, we report a
multi-wavelength observational study of a giant molecular cloud hosting the
S147/S153 complex (size ~90 pc X 50 pc). The selected complex is located in the
Perseus arm, and contains at least five HII regions (S147, S148, S149, S152,
and S153) powered by massive OB stars having dynamical ages of ~0.2 - 0.6 Myr.
The Canadian Galactic Plane Survey 12CO line data (beam size ~100".4) trace the
complex in a velocity range of [-59, -43] km/s, and also reveal the presence of
two molecular cloud components around -54 and -49 km/s in the direction of the
complex. Signatures of the interaction/collision between these extended cloud
components are investigated through their spatial and velocity connections.
These outcomes suggest the collision of these molecular cloud components about
1.6 Myr ago. Based on the observed overlapping zones of the two clouds, the
collision axis appears to be parallel to the line-of-sight. Deep near-infrared
photometric analysis of point-like sources shows the distribution of
infrared-excess sources in the direction of the overlapping zones of the
molecular cloud components, where all the HII regions are also spatially
located. All elements put together, the birth of massive OB stars and embedded
infrared-excess sources seems to be triggered by two colliding molecular clouds
in the selected site. High resolution observations of dense gas tracer will be
required to further confirm the proposed scenario.
