Influence of Wolf-Rayet stars on surrounding star-forming molecular
  clouds
  We investigate the influence of Wolf-Rayet (W-R) stars on their surrounding
star-forming molecular clouds. We study five regions containing W-R stars in
the inner Galactic plane ($l\sim$[14$^\circ$-52$^\circ$]), using
multi-wavelength data from near-infrared to radio wavelengths. Analysis of
$^{13}$CO line data reveals that these W-R stars have developed gas-deficient
cavities in addition to molecular shells with expansion velocities of a few km
s$^{-1}$. The pressure owing to stellar winds primarily drives these expanding
shells and sweeps up the surrounding matter to distances of a few pc. The
column densities of shells are enhanced by a minimum of 14% for one region to a
maximum of 88% for another region with respect to the column densities within
their central cavities. No active star formation - including molecular
condensations, protostars, or ionized gas - is found inside the cavities,
whereas such features are observed around the molecular shells. Although the
expansion of ionized gas is considered an effective mechanism to trigger star
formation, the dynamical ages of the HII regions in our sample are generally
not sufficiently long to do so efficiently. Overall, our results hint at the
possible importance of negative W-R wind-driven feedback on the gas-deficient
cavities, where star formation is quenched as a consequence. In addition, the
presence of active star formation around the molecular shells indicates that
W-R stars may also assist in accumulating molecular gas, and that they could
initiate star formation around those shells.
