On the star-forming ability of Molecular Clouds
  The star-forming ability of a molecular cloud depends on the fraction of gas
it can cycle into the dense-phase. Consequently, one of the crucial questions
in reconciling star-formation in clouds is to understand the factors that
control this process. While it is widely accepted that the variation in ambient
conditions can alter significantly the ability of a cloud to spawn stars, the
observed variation in the star-formation rate in nearby clouds that experience
similar ambient conditions, presents an interesting question. In this work we
attempted to reconcile this variation within the paradigm of colliding flows.
To this end we develop self-gravitating, hydrodynamic realisations of identical
flows, but allowed to collide off-centre. Typical observational diagnostics
such as the gas-velocity dispersion, the fraction of dense-gas, the column
density distribution ({\small N-PDF}), the distribution of gas mass as a
function of $K$-band extinction and the strength of compressional/solenoidal
modes in the post-collision cloud were deduced for different choices of the
impact parameter of collision. We find that a strongly sheared cloud is
terribly inefficient in cycling gas into the dense phase and that such a cloud
can possibly reconcile the sluggish nature of star-formation reported for some
clouds. Within the paradigm of cloud-formation via colliding flows this is
possible in case of flows colliding with a relatively large impact parameter.
We conclude that compressional modes - though probably essential - are
insufficient to ensure a relatively higher star-formation efficiency in a
cloud.
