Formation of massive stars

starforming-7001a.jpg(A. Maeder & L. Haemmerlé)

Most of massive stars are probably formed by accretion in a way similar to the low and intermediate mass stars. However the history of the accretion episodes, the mechanisms which determine the maximum mass of stars, the role of the metallicity, of rotation and of magnetic fields remain largely unknown.

The formation of massive stars is a key process to understand the links between stellar physics and the evolution of the galaxies. Among the most interesting questions behind that of the massive star formation, one finds the following ones:

  • What are the conditions required for the formation of massive stars ?
  • What are the feedbacks of massive star formation on their environment ?
  • To which extent the star formation is regulated by the formation of massive stars ?
  • What is the origin of the initial mass function ?
  • How this mechanism depends on the metallicity ?

In all these aspects, the physics of the formation of massive stars plays a key role and this is why we pursue our effort in this domain.

In the line of the work performed in previous years by Peter Nordberg, Paolo Bernasconi and Raoul Behrend, Lionel Haemmerlé has begun in April 2010 a PhD thesis on the formation of massive stars. The aim in this work is to test different scenarios for the evolution of the accretion rate during the pre- Main Sequence phase, and to account, during the formation phase, of the effects of rotation and magnetic fields.