New technique detects water vapour on Jupiter-like planet

As we rejoice the news of presence of water on Mars, researchers have now used a new technique to detect water in the atmosphere of an extra-solar planet of Jupiter-like mass orbiting a nearby star.

With further development and more sensitive instruments, this technique could help researchers learn about how many planets with water - like Earth - exist within our galaxy.

Researchers from California Institute of Technology and several other institutions have used a new technique to analyse the gaseous atmospheres of such extra-solar planets.

"When a planet transits or passes in orbit in front of its host star, we can use information from this event to detect water vapour and other atmospheric compounds," explained first author Alexandra Lockwood from Pasadena-based California Institute of Technology.

Alternatively, if the planet is sufficiently far away from its host star, we can also learn about a planet's atmosphere by imaging it, she added.

Lockwood and her adviser Geoffrey Blake, professor of cosmochemistry and planetary sciences and professor of chemistry, applied a novel technique to find water in a planetary atmosphere.

The method utilised the radial velocity (RV) technique - a technique commonly used in the visible region of the spectrum to which our eyes are sensitive - for discovering non-transiting exoplanets.

They expanded the RV technique into the infra-red to determine the orbit of the planet called 'Tau Bootis B' around its star and added further analysis of the light shifts via spectroscopy - an analysis of the light's spectrum.

Using data, the researchers were able to compare the molecular signature of water to the light spectrum emitted by the planet, confirming that the atmosphere indeed had water vapour.

"While the current technique cannot detect earth-like planets around stars like the sun, we can study the atmospheres of so-called 'super-earth' planets being discovered around nearby low-mass stars, many of which do not transit," informed Blake.

The new results appeared in the Astrophysical Journal Letters.