Background
Cosmic cashew nut
Wednesday 19 June 2013

Planets are created from a large disk of dust and ice revolving around a young star, where they crystallise, as it were: small lumps attract others and form larger lumps that, in turn, attract others. Eventually, you have a whole planet with, in at least one instance, newspaper readers.

But why don’t those lumps fall towards the star? Evidently, there are safe havens, the cosmic equivalent of that corner of your house where dust collects. In last week’s Science, Leiden astronomers describe a dust trap close to the star Oph IRS 48. The cloud of dust around the star is shaped like a cashew nut instead of a circle: something – perhaps a planet or a brown dwarf – has swept up the dust. The cashew-nut shape had already been predicted by mathematical models: due to the turbulence in the cloud, the dust particles are trapped and can stick together without falling towards the star.