The stellar initial mass function

• Applicant: Professor Dr. Pavel Kroupa
• Subject Area: Astrophysics and Astronomy
• Term: from 2003 to 2006
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5386742

The outcome of star formation are stars and sub-stellar objects with a range of masses. Astrophysicists refer to the distribution of masses as the initial mass function (IMF). The IMF together with the time-modulation of the star-formation rate dictates the evolution and fate of galaxies and star clusters, and is therefore one of the most fundamental astrophysical distribution functions. Despite its importance, and despite a very large research effort with significant advances, we still do not know the exact shape of the IMF, nor has unambiguous evidence for a variation of the IMF with star-forming conditions been found. The project outlined here addresses both these important issues. A novel iterative method is to be applied to distill the shape of the IMF non-parametrically from an observed stellar luminosity function (the distribution function of stellar luminosities), and the bias due to unresolved multiple systems is to be quantified for massive stars. Another aim is to investigate how dissolving star clusters affect the measurement of an IMF, and what the origin of sub-stellar objects including brown dwarfs and the observed planets may be.

• DFG Programme: Research Grants