I am doing computer simulations of stellar atmospheres. Stars have atmospheres just like the Earth. When we look at the stars we see their light, but inspite of the light that is created in the very inside of the star we only see the light originating from the atmosphere. So the atmosphere of a star is crucial when trying to understand stellar light. We think that round about one third of the stars in our Milky Way are binary stars! So what happens if we don't look at only one star but at a binary star system? How is the light affected by this? This is what I study and therefore I concentrate on a star called AA Doradus which can only be seen from the southern hemisphere. This binary star system is special because both components are very close but one of the stars is really hot (8x hotter than our sun) and the other one is so cool that it is almost no star anymore (less than half as hot as our sun). By being so close to each other it happens that the hot star heats up the cooler one - but only on the side that is facing him.
I am doing computer simulations of this cool companion on high performance clusters. When comparing different sets of simulations to observations I try to find out what effects play a significant role in shaping the light we observe from binary star systems like these.