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Centro de Astrofísica da Universidade do Porto

From Clouds to Stars

Stefan Schmeja

Sessão 1: The Turbulent Interstellar Medium
28 março 2007

As stars are believed to form in turbulent molecular clouds, in the first lecture the main properties of the interstellar medium will be reviewed and an introduction to the concept of turbulence will be given. Observations indicate that the interstellar medium is highly turbulent, driven on different length scales by various processes. Supersonic turbulence causes a complex network of interacting shocks and converging flows, creating distinct structures like filaments and shells. This leads to regions of high density that may eventually become gravitationally unstable and collapse.

Sessão 2: Star Formation Theory
26 abril 2007

This lecture will give an overview of star formation theories from early solar nebula hypotheses to the current picture of gravoturbulent fragmentation. The findings of Sir James Jeans that there is a critical mass of the gas above which gravity supersedes the thermal pressure, resulting in the collapse of the cloud, led to today's perception of star formation. While the so-called standard theory of star formation sees magnetic fields and ambipolar diffusion as the main controlling agent of molecular clouds, it is meanwhile argued that star formation is the result of a complex interplay between gravity and supersonic turbulence.

Sessão 3: Numerical Simulations
9 maio 2007

Numerical simulations are a very useful and widely used tool to study the process of star formation. This lecture will give a basic introduction on hydrodynamics, discuss different computational approaches, and will show some of the results that can be achieved by simulations.

Sessão 4: The Structures of Clouds and Clusters
16 maio 2007

Molecular clouds usually show a very complex hierarchical structure that is often described as self-similar or fractal. Young star clusters can also be hierarchical, showing a stellar surface density distribution with multiple peaks and possible fractal substructure, or they are centrally condensed, exhibiting centrally concentrated stellar surface density distributions with relatively smooth radial profiles. This lecutre will review several statistical methods used to describe (and ideally quantify) the geometrical structures of both point sets (star clusters) and grey-scale data (molecular clouds).