New Exoplanet Discovered

An extrasolar planet has been found by observing subtle changes in a star’s position in the sky for the first time. The technique, called astrometry, is best suited to finding planets at great distances from their stars, complementing more common techniques, which tend to turn up planets orbiting their stars at close range.

The planet’s star is also the lightest known to host a planet, and researchers hope other such discoveries will shed light on how common planets are around low-mass stars, which far outnumber their higher-mass cousins.

Most of the 350 or so known exoplanets have been discovered by the so-called radial velocity technique. Stars and planets actually orbit each other around their common centre of mass, and this method looks for telltale shifts in a star’s light spectrum that indicate the star is wobbling due to an orbiting exoplanet.

Another popular technique looks for periodic dips in a star’s brightness that occur when an orbiting planet passes in front of, or transits, its star. [Read more]

Maggie McKee, 28th May 2009, New Scientist [http://www.newscientist.com/article/dn17208-exoplanet-found-by-measuring-stars-sideways-shift.html]