Abstract

Star formation plays a major role in the evolution of our Universe and understanding the circumstellar (CS) environment of protostars and young stars can also provide crucial information on how planets form.

A number of unsolved problems in high and low mass star and planet formation depend on our understanding of the way radiation from newly born stars interacts with their circumstellar environments. In this talk I will review some of the open questions that relate to this radiation feeback, as well as outline how these are currently being or will be tackled in the near future.

In particular I will present some of our recent results on the evolution and dispersal of protoplanetary disks irradiated by active young stellar objects (YSOs). Through detailed thermochemical and hydrodynamical simulations we find that that X-rays from the central YSOs may drive powerful outflows which may be responsible for the dispersal of the disks. The timescales for dispersal have direct consequences on planet formation, which will also be discussed.

Moving onto larger scales I will show how massive OB stars can shape their surrounding by means of ionising radiation influencing the formation of successive generation of stars, and driving turbulence in the interstellar medium.

During the course of my talk a brief introduction will be given to the 3D photoionisation and dust radiative transfer Monte Carlo code, MOCASSIN (Ercolano et al., 2003, 2005, 2008), which is a crucial tool for the study of radiation trasport in complex density and radiation fields.