Two baby planets guzzling gas from a 'parent' star found

Seen by Earth's largest radio telescope, vast streams of gas flowing through a gap in a disc of material around a young star seem to support theories of how the planets grow.

The Atacama Large Millimetre/submillimeter Array (ALMA) in Chile's Atacama desert reaches farther beyond the skies than any other radio telescope.

Vast streams of gas are flowing across a gap in the disc of material around a young star, The European Southern Observatory (ESO) said in a statement.

Astronomers studied the young star HD 142527, over 450 light-years from Earth, which is surrounded by a disc of gas and cosmic dust - the remains of the cloud from which the star formed. The study result was published in the journal Nature.

The dusty disc is divided into an inner and an outer part by a gap, which is thought to have been carved by newly forming gas giant planets clearing out their orbits as they circle the star.

The inner disc reaches from the star out to the equivalent of the orbit of Saturn in the Solar System, while the outer disc begins about 14 times further out.

The outer disc does not surround the star uniformly, instead, it has a horseshoe shape, probably caused by the gravitational effect of the orbiting giant planets.

According to theory, the giant planets grow by capturing gas from the outer disc, in streams that form bridges across the gap in the disc.

"Astronomers have been predicting that these streams must exist, but this is the first time we have been able to see them directly," said Simon Casassus, who led the study.

Casassus and his team used ALMA to look at the gas and cosmic dust around the star, seeing finer details, and closer to the star, than could be seen with previous such telescopes.

The gap in the dusty disc was already known, but they also discovered diffuse gas remaining in the gap, and two denser streams of gas flowing from the outer disc, across the gap, to the inner disc.

"We think that there is a giant planet hidden within, and causing, each of these streams. The planets grow by capturing some of the gas from the outer disc, but they are really messy eaters: the rest of it overshoots and feeds into the inner disc around the star" said researcher Sebastian Perez.

The observations answer another question about the disc around HD 142527. As the central star is still forming, by capturing material from the inner disc, it would have already been devoured, if it was not somehow topped up.