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Top: the two stars in real physical space. Colors show their common gravitational field; the grey shaped region around them approximately indicate the Roche-lobe (i.e. the closermost common gravitational equipotential surface). If one of the stars puffs up to fill the Roche-lobe, its mass starts to flow towards the companion. Bottom left: Hertzsprung--Russell diagram of both binary companions. Bottom right: time evolution of the radial distance between the two stars (with the center of mass at zero). When the contact phase happens at 3.1775~Myr, the orbit quickly changes due to the change in relative masses: the mass gainer (the secondary) moves closer to the center of mass, while the mass donor (the primary) moves away from it. The underlying data for this animation was kindly provided by Athira Menon; the binary model was computed by her with the MESA code. The animation was designed and rendered by Dorottya Szécsi who works as a research fellow and a stellar evolution expert associated with Prof. Walch-Gassner's group.

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 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