Radiation feedback in high and low mass star and planet formation

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 feedback, 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 X-rays
from active young stellar objects (YSOs). The timescales for dispersal
have direct consequences on planet formation, which will also be
discussed.

Finally, moving onto larger scales I will discuss 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. Understanding the extent and
efficiency of this radiation feedback requires the solution of the
radiative transfer problem in the context of large scale
hydrodynamical simulation. Recent efforts to push the state of the art
(hydro + photoionisation codes) in the context of star formation will
be discussed.