• Question: what software do you use to create planets?

    Asked by Johnster to Stefan, Anna on 11 Nov 2014. This question was also asked by Holly.
    • Photo: Stefan Lines

      Stefan Lines answered on 10 Nov 2014:

      I use two codes to make planets. One is used to simulate the rocky material (called PKDGRAV) and one is used to model the gas (called FARGO).

      PKDGRAV is a custom written code, written in C. It’s a super-fast N-body code, which means its job is to calculate the forces between multiple (N) bodies. In my case N = 1,000,000. The code effectively has to calculate the gravity felt by every single rock on each other – and all the rocks from the gravity of the binary stars. As you can imagine, this is extremely time consuming. It takes days, weeks, months or even years depending on how long you run it for – even using super computers. A really important part of the code though is the collisions. When the rocks collide with each other, we use a really complex model to determine whether the rocks merge together and get bigger, bounce off each other or even explode.

      Even if you’re not interested in making Gas Giants, modelling the gas disk is still really important. That is because gas can exert drag on the rock, just like we have air or wind resistance here on earth. That’s when I use FARGO.

      Links:

      PKDGRAV: http://hpcc.astro.washington.edu/faculty/trq/brandon/pkdgrav.html

      FARGO: http://fargo.in2p3.fr/

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