Astronomers identify new method of planet formation
Scientists have suggested a new explanation for the abundance in intermediate-mass exoplanets – a long-standing puzzle in astronomy. In the last 25 years, scientists have discovered over 4000 planets outside our solar system. From relatively small rock and water worlds to blisteringly hot gas giants, these planets display a remarkable variety. This variety is not unexpected. The computer models which scientists use to study the formation of planets predict this variety as well. What the models struggle to explain is the observed mass distribution of exoplanets. The majority fall in the intermediate-mass category – planets with masses of several Earth masses to around that of Neptune. Even in our own solar system, the formation of Uranus and Neptune remains a mystery.
Now, scientists from the Universities of Cambridge and Zurich, associated with the Swiss NCCR PlanetS, have proposed an alternative explanation. Their results are published in the journal Nature Astronomy. In this process, dust and gas in the disk clump together due to gravity and form dense spiral structures. These then grow into planetary building blocks and eventually planets. The scale on which this process occurs is very large – spanning the scale of the protoplanetary disk. These magnetic fields stir up the gas and dust of the disk and influence the formation of the planets. However, the differences in scale and nature of gravity and magnetism make the two forces challenging to integrate into the same planetary formation model. So far, computer simulations that capture the effects of one of the forces well usually do poorly with the other.
To succeed, the team developed a new modelling technique. First, they needed a deep theoretical understanding of both gravity and magnetism. Then, they had to find a way to translate the understanding into a code that could efficiently compute these contrasting forces in unison. Finally, due to the immense number of necessary calculations, a powerful computer was required – like the Piz Daint at the Swiss National Supercomputing Centre (CSCS).
(Content Courtesy: https://www.cam.ac.uk/research/news/astronomers-identify-new-method-of-planet-formation)