Scientific rationale

Stars are one of the fundamental building blocks of the Universe:  the source of most of the chemical elements, a crucial ingredient in the formation and evolution of galaxies, the progenitors of supernovae, gamma ray bursts, and black holes, the hosts of planetary systems, and the sustainer of life. In some ways, stars are relatively simple objects; the evolution and fate of a star is almost uniquely determined by its mass. However, the formation of a star is anything but simple, involving a complex interplay between gravity, hydrodynamics, magnetic fields, radiation transport, and chemistry. Great progress has been made in delineating the roles of these physical processes through theory and observations, but a fundamental mystery remains, one of the most important questions in astronomy. What determines the masses of stars and how does the distribution of stellar masses arise, the so-called Initial Mass Function (IMF)?

We expect that progress in answering this question will accelerate with the advent of several new instruments operating at (sub-)mm wavelengths and the increasing ability for numerical models to include the relevant physics. The Herschel Space Observatory has just begun science observations, SCUBA-2 on the JCMT has just become operational, and the first early science observations with ALMA should be made in the year following this meeting.  On the theoretical side, hydrodynamical simulations of star formation have been able to begin including magnetic fields, radiation transport, and chemistry.

Thus, the time is right for a meeting focussing on the observational and theoretical aspects of the origin of stellar masses, with the programme centred around three topical questions:

• From clouds to core to protostars: what processes are involved in transforming molecular clouds into clusters of protostars?
• The birth and influence of massive stars: how and why do massive stars form and what is their influence on further star formation?
• The physics of the low-mass end of the IMF: how and why do brown dwarfs form, and what is the physics of their atmospheres?

In recognition of the fact that this field is highly active with many young researchers, there will be an emphasis on talks given by young researchers and the programme will include ample time for discussion led by panels of experience researchers.