Star formation in turbulent molecular clouds with colliding flow
  Using self-gravitational hydrodynamical numerical simulations, we
investigated the evolution of high-density turbulent molecular clouds swept by
a colliding flow. The interaction of shock waves due to turbulence produces
networks of thin filamentary clouds with a sub-parsec width. The colliding flow
accumulates the filamentary clouds into a sheet cloud and promotes active star
formation for initially high-density clouds. Clouds with a colliding flow
exhibit a finer filamentary network than clouds without a colliding flow. The
probability distribution functions (PDFs) for the density and column density
can be fitted by lognormal functions for clouds without colliding flow. When
the initial turbulence is weak, the column density PDF has a power-law wing at
high column densities. The colliding flow considerably deforms the PDF, such
that the PDF exhibits a double peak. The stellar mass distributions reproduced
here are consistent with the classical initial mass function with a power-law
index of $-1.35$ when the initial clouds have a high density. The distribution
of stellar velocities agrees with the gas velocity distribution, which can be
fitted by Gaussian functions for clouds without colliding flow. For clouds with
colliding flow, the velocity dispersion of gas tends to be larger than the
stellar velocity dispersion. The signatures of colliding flows and turbulence
appear in channel maps reconstructed from the simulation data. Clouds without
colliding flow exhibit a cloud-scale velocity shear due to the turbulence. In
contrast, clouds with colliding flow show a prominent anti-correlated
distribution of thin filaments between the different velocity channels,
suggesting collisions between the filamentary clouds.
