Stars are formed out of dust and gas collected in large molecular clouds, where gravity in the heaviest of the clumps overcomes pressure, causing gas and dust to accumulate, collapse, and turn into a star. Around the star there is a so-called growth disc, where the material from the cloud falls down and is sent in rotation around the newly formed star. Most of the material is transported through the dial and into the star or sent out in strong winds, while a tiny percentage eventually turns into planets – in a complicated process we don't quite understand. Physics is driven by an interplay between gas dynamics, magnetic fields, radiation that heats and cools gas and gravity.

Over the last 10 years, we have learned a great deal from detailed observations of newly formed stars, but the problem of astronomy has always been that you cannot do controlled laboratory experiments. It is difficult to build a star in the basement of the Niels Bohr Institute, nor can we see it all from different angles, but instead get a projected image in the sky, taken to a certain time. Although we can write beautiful equations describing the physics behind them, they are not binary. You can't just count on the result in your hand, just as it's hard to predict the weather, just with knowledge of gas dynamics and cloud formation. At the Niels Bohr Institute we have a very long tradition of using the largest computers in the world to better understand the universe in close cooperation with observers. Computer models are therefore a key tool today for astronomy, and form our virtual laboratory, which can not only make great films and fine images, but also illuminate what are the most important physical processes. That is the focus of my research, and I will tell you about how we now believe that star systems are being made.