Water vapour detected around a 'hot Jupiter'

In a quest for life beyond earth, scientists at the US Naval Research Laboratory (NRL) have detected water vapour in the atmosphere of a 'hot Jupiter' outside our solar system.

The team applied a sophisticated Doppler technique to the infra-red to directly detect the planet and demonstrate the presence of water in its atmosphere.

The planet, named tau Boo b, orbits the nearby star tau Bootis and belongs to a class of exotic planets called 'hot Jupiters' that are not found in our solar system.

"The detection of water vapour in tau Boo b is an exciting and important step in understanding the composition of these exotic planets," said an ecstatic John Carr, a researcher in NRL's remote sensing division.

The result also demonstrates the power of this technique for measuring water and other molecules in the atmospheres of planets- giving scientists a new tool to study the nature and evolution of extrasolar planets.

A 'hot Jupiter' is a massive extrasolar planet that orbits very close to its parent star.

Unlike our Jupiter, which is fairly cold and has an orbital period of about 12 years, tau Boo b orbits its star every 3.3 days and is heated to extreme temperatures by its proximity to the star.

The research team studied data collected at the WM Keck Observatory in Hawaii, using the Near Infrared Echelle Spectrograph instrument.

By comparing the molecular signature of water to the combined light spectrum of the planet and star, the scientists were able to measure the motion of the planet as it orbits the star and establish the presence of water vapour in the planet's atmosphere.

The team also determined that the planet is six times more massive than Jupiter, said the study reported by the Astrophysical Journal Letters.

Prior to this, scientists have reported detections of water for just a few other extrasolar planets.

The research team included scientists from California Institute of Technology, Harvard-Smithsonian Center for Astrophysics, Pennsylvania State University and University of Arizona.