PerspectiveAstronomy

A Trap for Planet Formation

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Science  07 Jun 2013:
Vol. 340, Issue 6137, pp. 1179-1180
DOI: 10.1126/science.1239404

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Summary

The raw material for forming planets is micrometer to millimeter-sized particles of dust that orbit along with gas in protoplanetary disks around young low-mass stars. These disks are known to be common and to persist for several million years (1). The Kepler mission (2) showed that mature planetary systems are also common. What is not known, however, is the full sequence of steps that allows the dust within protoplanetary disks to grow into planets. On page 1199 of this issue, van der Marel et al. (3) report observations from the Atacama Large Millimeter/submillimeter Array (ALMA) that hint at how the most problematic step may be surmounted—millimeter-sized particles are seen to be accumulating into a giant trap that acts as a holding pen for growth into larger bodies.