  We investigate the effect of heating by luminosity sources in a simulation of
clustered star formation. Our heating method involves a simplified continuum
radiative transfer method that calculates the dust temperature. The gas
temperature is set by the dust temperature. We present the results of four
simulations, two simulations assume an isothermal equation of state and the two
other simulations include dust heating. We investigate two mass regimes, i.e.,
84 Msun and 671 Msun, using these two different energetics algorithms. The mass
functions for the isothermal simulations and simulations which include dust
heating are drastically different. In the isothermal simulation, we do not form
any objects with masses above 1 Msun. However, the simulation with dust
heating, while missing some of the low-mass objects, forms high-mass objects
(~20 Msun) which have a distribution similar to the Salpeter IMF. The envelope
density profiles around the stars formed in our simulation match observed
values around isolated, low-mass star-forming cores. We find the accretion
rates to be highly variable and, on average, increasing with final stellar
mass. By including radiative feedback from stars in a cluster-scale simulation,
we have determined that it is a very important effect which drastically affects
the mass function and yields important insights into the formation of massive
stars.
