Star-forming sites IC 446 and IC 447: an outcome of end-dominated
  collapse of Monoceros R1 filament
  We present an analysis of multi-wavelength observations of Monoceros R1 (Mon
R1) complex (at d ~760 pc). An elongated filament (length ~14 pc, mass ~1465
Msun) is investigated in the complex, which is the most prominent structure in
the Herschel column density map. An analysis of the FUGIN 12CO(1-0) and
13CO(1-0) line data confirms the existence of the filament traced in a velocity
range of [-5, +1] km/s. The filament is found to host two previously known
sites IC 446 and IC 447 at its opposite ends. A massive young stellar object
(YSO) is embedded in IC 446, while IC 447 contains several massive B-type
stars. The Herschel temperature map reveals the extended warm dust emission (at
T_d ~ 15-21 K) toward both the ends of the filament. The Spitzer ratio map of
4.5 micron/3.6 micron emission suggests the presence of photo-dissociation
regions and signature of outflow activity toward IC 446 and IC 447. Based on
the photometric analysis of point-like sources, clusters of YSOs are traced
mainly toward the filament ends. The filament is found to be thermally
supercritical showing its tendency of fragmentation, which is further confirmed
by the detection of a periodic oscillatory pattern (having a period of ~3-4 pc)
in the velocity profile of 13CO. Our outcomes suggest that the fragments
distributed toward the filament ends have rapidly collapsed, and had formed the
known star-forming sites. Overall, the elongated filament in Mon R1 is a
promising sample of the "end-dominated collapse" scenario, as discussed by Pon
et al. (2011, 2012).
