November 18, 2011

The Herschel satellite discovered a water reservoir around a young star

The ESA's Herschel satellite, in which CNES is participating, discovered water vapour around a young star. It would come from the ice-covered dust of the matter disk orbiting the star. This ice would contain enough water to cover several planets.

A new born standing in water

HERSCHEL focused on TW Hydrae, a star which is only approximately ten million years old. Located at approximately 170 light years away from Earth in the Hydra constellation, the star is still surrounded by a disk composed of dust and gas which could give rise to a whole planetary system in the next millions years.

HERSCHEL detected great quantities of cold water vapour (approximately -170ºC) in this disk. This vapour could have been produced by the star's strong radiations by spraying ice which covered the dust orbiting the star.

“The water vapour changes the star's light detected by HERSCHEL, thus revealing the presence of ice which would have been undetectable in the disk” Olivier La Marle, astrophysics program scientist at CNES, explained.

Double hit for comets

The data were obtained thanks to the HERSCHEL's HIFI spectrometer which was recently very successful confirming that some comets of the Solar System contain water ice similar to the Earth's water.

HIFI, in which CNES is participating through different institutes, supports the theory that our planet could come from a specific type of comets, formed in the outer areas of our solar system.

However, thanks to simulations, astronomers admitted that there is around TW Hydrae enough ice water to build a real stock of comets, enough to fulfil several thousands of terrestrial oceans.

“This theory started out with the HERSCHEL recent results and suggested that the water on Earth could result from a ice comet bombardment coming from the original disk” Olivier concluded.

The next step for the team: study 3 other young systems in which planets could form to also detect water ice in significant quantity.

See also