Star formation in evolving molecular clouds
  Molecular clouds are the principle stellar nurseries of our universe, keeping
them in the focus of both observational and theoretical studies. From
observations, some of the key properties of molecular clouds are well known but
many questions regarding their evolution and star formation activity remain
open. While numerical simulations feature a large number and complexity of
involved physical processes, this plenty of effects may hide the fundamentals
that determine the evolution of molecular clouds and enable the formation of
stars. Purely analytical models, on the other hand, tend to suffer from rough
approximations or a lack of completeness, limiting their predictive power. In
this paper, we present a model that incorporates central concepts of
astrophysics as well as reliable results from recent simulations of molecular
clouds and their evolutionary paths. Based on that, we construct a
self-consistent semi-analytical framework that describes the formation,
evolution and star formation activity of molecular clouds, including a number
of feedback effects to account for the complex processes inside those objects.
The final equation system is solved numerically but at much lower computational
expense than, e.g., hydrodynamical descriptions of comparable systems. The
model presented in this paper agrees well with a broad range of observational
results, showing that molecular cloud evolution can be understood as an
interplay between accretion, global collapse, star formation and stellar
feedback.
