The origin of stars. Tales of the unexpected in extreme environments

PhD ceremony: Mr. S. Höçük, 16.15 uur, Aula Academiegebouw, Broerstraat 5, Groningen

Dissertation: The origin of stars. Tales of the unexpected in extreme environments

Promotor(s): prof. M. Spaans

Faculty: Mathematics and Natural Sciences

This thesis tries to gain insight into the formation of stars in extreme environments. In particular, the dependence of the renowned initial mass function (IMF) is considered. The initial mass function gives the relative distribution of stellar masses in a given volume of space. It is an empirically derived function that behaves as a power law according to observations. This distribution has become an important diagnostic tool for astronomers and is of fundamental importance in many research areas. The idea is that the IMF should be a universal function. However, it is uncertain whether stars in extreme environments form in the same way and if the IMF is similar to those in our Galaxy. In this thesis, the universality of this much debated function is tested under different environmental conditions, using detailed numerical simulations. Each chapter focuses on a different aspect of star formation. Chapter 2 focuses on the fragmentation properties of giant molecular clouds, Chapter 3 on the formation of stars in X-ray dominated molecular clouds and the resulting stellar mass functions, and Chapter 4 on the formation of stars in molecular clouds under different, but strong feedback effects from black holes. All the results of the various studies in this thesis lead to the same outcome. If the environmental conditions are extreme enough, chemically, mechanically or radiatively, then the initial mass function differs from the IMF as observed in our galaxy and it deviates from the theorized universal form.

Read on: http://www.rug.nl/corporate/nieuws/kortNieuws/2010/superzwaarzwartgat