On the distribution of protostar masses
  The distribution of protostar masses is studied for core-environment systems
whose duration of infall follows a waiting-time distribution. Each
core-environment system has a continuous density profile with no barrier to
mass flow. The core is an isothermal sphere and the environment is a filament,
a layer, or a uniform medium. The infall is terminated by gas dispersal due to
outflows and turbulence. The distribution of infall durations is a declining
exponential, the simplest waiting-time distribution. The resulting distribution
of protostar masses closely resembles the initial mass function, provided the
environment density is sufficiently high, and the distribution of initial core
masses is sufficiently narrow. The high-mass tail of the mass function
increases strongly with environment density and weakly with environment
dimension. Isolated regions of low environment density form protostars of low
mass from within the parent core. In contrast, clustered regions of high
environment density form protostars of low mass from core gas, and protostars
of high mass from core and environment gas.
