Gas-powered planet formation witnessed in ‘wheel-in-wheel’ binary star system

31 Oct 2014

This artist's impression shows the dust and gas around the double star system GG Tauri-A. Image via ESO/L. Calçada

For the first time ever, researchers may have witnessed why planet-forming material sticks together – because of complementary gas flows.

Scientists in France recently detected a stream of gas flowing from a massive outer disc toward the inner reaches of a binary star system.

Half of sun-like stars are born in binary systems, which means these findings could have significant consequences in the hunt for exoplanets.

A research group led by Anne Dutrey from the Laboratory of Astrophysics of Bordeaux, and CNRS used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe the distribution of dust and gas in a multiple-star system called GG Tau-A.

This object is only a few million years old and lies about 450 light years from Earth, in the constellation of Taurus.

“Like a wheel in a wheel, GG Tau-A contains a large, outer disc encircling the entire system, as well as an inner disc around the main central star,” reports ESO, a ground-based astronomical observatory.

“This second inner disc has a mass roughly equivalent to that of Jupiter. Its presence has been an intriguing mystery for astronomers since it is losing material to its central star at a rate that should have depleted it long ago.”

While observing these structures with ALMA, the team finally spotted gas clumps in the region between the two discs. The new observations suggest that material is being transferred from the outer to the inner disc, creating a sustaining lifeline between the two.

“Material flowing through the cavity was predicted by computer simulations but has not been imaged before. Detecting these clumps indicates that material is moving between the discs, allowing one to feed off the other,” explains Dutrey.

“These observations demonstrate that material from the outer disc can sustain the inner disc for a long time. This has major consequences for potential planet formation.”

This wide-field view shows the sky around the young multiple star system GG Tauri, which appears very close to the centre of this picture. This view also shows a dust cloud and evidence of star formation near the top of the picture. Image via ESO/Digitized Sky Survey 2

Gordon Hunt was a journalist with Silicon Republic