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Mathematisch-Naturwissenschaftliche FakultätAstrophysik I.Physik

Theoretical Astrophysics group Cologne - TAC

Our research deals with the numerical modelling of the star formation process by means of high-performance, 3D, magneto-hydrodynamical (MHD) simulations. The simulations cover large spatial scales from ISM physics on kpc scales over molecular clouds on scales of 10 - 100 pc to star forming filaments on (sub-) pc scales and finally to protostellar discs and jets on scales of 10 - 1000 AU.

In our research group we use several tools like the (M)HD codes FLASH, GADGET, GANDALF, the astrochemical code KROME, 3D-PDR or radiative transport codes like RADMC-3D and POLARIS.

Prof. Dr. Stefanie Walch-Gassner is the head of the SILCC project (SImulating the life Cyle of molecular Clouds), a collaboration of several European astrophysical institutes, which has set the aim to model the formation, evolution, and dispersal of molecular clouds in 3D, MHD simulations with particular focus on a detailed astro-chemical modelling and the inclusion of various feedback processes.

Contact information:

  • Phone: (+49|0) 221 / 470 - 3497
  • Fax: (+49|0) 221 / 470 - 5162
  • Email: walch [at] ph1.uni-koeln.de

Consultation hours

upon agreement in Room 1.14, Building 312 

Monthly Highlight

Multi-band ray-tracing of ionizing photons

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  • Fig. 1) Example SED for a star with surface temperature 50,000 K. Shown is the simple black body spectrum for T=50,000 K as well as a more realistic SEDs. The blue and red lines indicate how the ionizing part of the spectrum can be divided into two or more energy bands. Each energy band has its own mean photon energy and interacts with the gas slightly differently.
  • Fig. 2) The radial temperature profile of an HII region in a uniform medium simulated with the new multi-band ray-tracing method is shown as the black line. The temperature rises towards larger radii, because the H and He ionization cross sections decrease with the photon energy, ie. photons with lower energies are absorbed preferably. The inner peak marks the edge of the He II region. The outer peak is at the edge of the HII region. The ionization states of C are plotted as orange lines and of He as blue lines.