Comet Factory Discovered

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ALMA Discovers Comet Factory

New observations of a “dust trap” around a young star solve long-standing planet formation mystery

Astronomers using the new Atacama Large Millimeter/submillimeter Array (ALMA) have imaged a region around a young star where dust particles can grow by clumping together. This is the first time that such a dust trap has been clearly observed and modelled. It solves a long-standing mystery about how dust particles in discs grow to larger sizes so that they can eventually form comets, planets and other rocky bodies. The results are published in the journal Science on 7 June 2013.

Astronomers now know that planets around other stars are plentiful. But they do not fully understand how they form and there are many aspects of the formation of comets, planets and other rocky bodies that remain a mystery. However, new observations exploiting the power of ALMA are now answering one of the biggest questions: how do tiny grains of dust in the disc around a young star grow bigger and bigger — to eventually become rubble, and even boulders well beyond a metre in size?

Source

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Dust trap animation

This artist’s rendering shows the behaviour of different sized particles in the disc of dust that surrounds Oph-IRS 48 system. The bigger particles, millimetres in diameter, tend to clump together in a safe haven that allows them to grow even further, eventually forming boulders and then comets.

Credit: ESO/L. Calçada

Source: ESO Observatory

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Zooming in on the Oph IRS 48 system

This video zooms in on the Oph-IRS 48 system where a dust trap allowing dust particles to grow and spawn bigger bodies has been observed for the first time.

Credit: ALMA (ESO/NAOJ/NRAO)/Nick Risinger (skysurvey.org)/Digitized Sky Survey 2/S. Guisard (www.eso.org/~sguisard). Music: movetwo

Source: ESO Observatory

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Computer simulation of dust trap formation

This computer simulation shows how a vortex can form when a massive planet is interacting with a disc around a young star. It shows how the gas density evolves when there is a planet, with a mass ten times that of Jupiter, located at 20 times the Earth-Sun distance from the central star. A large-scale vortex is created at the outer edge of the gap, which can live for more than 1000 of the planet's orbits. This vortex can trap millimeter-sized particles over million years timescales and explain the high contrast structure observed with ALMA in the disc around Oph-IRS 48.

Credit: P. Pinilla/ESO

Source: ESO Observatory