The molecular cloud S242: physical environment and star formation
  activities
  We present a multi-wavelength study to probe the star formation (SF)
processes on a larger scale (~1.05 deg x 0.56 deg) around the S242 site. The
S242 molecular cloud is depicted in a velocity range from -3.25 to 4.55 km/s
and has spatially elongated appearance. Based on the virial analysis, the cloud
is prone to gravitational collapse. The cloud harbors an elongated filamentary
structure (EFS; length ~25 pc) evident in the Herschel column density map and
the EFS has an observed mass per unit length of ~200 M_sun/pc exceeding the
critical value of ~16 M_sun/pc (at T = 10 K). The EFS contains a chain of
Herschel clumps (M_clump ~150 to 1020 M_sun), revealing the evidence of
fragmentation along its length. The most massive clumps are observed at both
the EFS ends, while the S242 HII region is located at one EFS end. Based on the
radio continuum maps at 1.28 and 1.4 GHz, the S242 HII region is ionized by a
B0.5V - B0V type star and has a dynamical age of ~0.5 Myr. The photometric 1 -
5 microns data analysis of point-like sources traces young stellar objects
(YSOs) toward the EFS and the clusters of YSOs are exclusively found at both
the EFS ends, revealing the SF activities. Considering the spatial presence of
massive clumps and YSO clusters at both the EFS ends, the observed results are
consistent with the prediction of a SF scenario of the end-dominated collapse
driven by the higher accelerations of gas.
