Potentially habitable planet found

A rocky planet with the potential to support liquid waterand therefore the potential to support lifehas been found orbiting a sun-like star near our solar system.

The planet, known as HD 85512 b, is among 50 planets outside our solar system,calledexoplanets, recently discovered using the HARPS instrument on the 3.6-metre telescope at La Silla Observatory in Chile, operated by the European Southern Observatory.

The findings were announced Monday at a conference on Extreme Solar Systems in Grand Teton National Park, Wyo., by an international team led by Michel Mayor at the University of Geneva in Switzerland. They will be published as three articles in an upcoming issue of the journal Astronomy & Astrophysics.

HD 85512 b has a mass about 3.6 times greater than the Earth's, making it a class of rocky planet called a "super-Earth." Such planets don't exist in our solar system, but appear to be common around other stars. The planetorbits the star HD 85512 in the southern constellation Vela (The Sail), which isonly visible at latitudesbelow 30 degrees north. Theorbit grazes theedge of the habitable zone around its starthe bandaround the starwhere the temperature could potentially allowliquid waterto exist if conditions are right.

The newexoplanetwas discovered during a survey that focused on 10 nearby stars similar to the sun. The survey found more than 50 new planets around them, including 16 super-Earths, defined as being more massive than the Earth, but less than 10 times more massive.

Of the 16 super-Earths, five were less than five times more massive than the Earth, including HD 85512 b.

"These planets will be among the best targets for future space telescopes to look for signs of life in the planet's atmosphere by looking for chemical signatures such as oxygen," said Francesco Pepe, an astronomer at the Geneva Observatory in Switzerland who was the lead author on one of the papers describing the findings.

The technique used by the HARPS instrument is called the radial velocity technique or Doppler spectrometry. It measures small changes in the movement of stars caused by the tug of a nearby planet's gravity. The changes result in a Doppler shiftsmall shifts in the colour of lightas the light-emitting star moves toward or away from the Earth.

Over 600 exoplanetsandmore than 1,000 other potentialexoplanets have been discovered using HARPS and NASA's Kepler telescope. But onlyone other planet has been found on the edge of the habitable zone of a star.

That planet, called Gliese 581 d, is another super-Earth discovered using HARPS in 2007. Scientists announced another planet in the same system called Gliese 581 g in 2010 that appeared to be right in the middle of the habitable zone. However, that planet was later shown not to existscientists had misinterpreted the data.