Planet Hunters Triple Their Pleasure

Planet Hunters Triple Their Pleasure
http://sciencenow.sciencemag.org/cgi...ull/2006/517/2

By Robert Irion
ScienceNOW Daily News
17 May 2006

A new system of three extrasolar planets is delighting astronomers by
virtue of something that it lacks: a Jupiter-size bully to throw its
gravitational weight around. The worlds, roughly the mass of Neptune
and perhaps made mostly of rock and ice, revolve in orderly,
undisturbed paths around a small star just 41 light-years away. The
star also appears to host a band of asteroids, giving the system a
tantalizing hint of home. What's most exciting about the find,
astronomers say, is that "super-Earths" with solid surfaces are now
likely to be plentiful in the universe.

The discoveries raise the census of known exoplanets above 190, nearly
all of them found by detecting the slight wobbles of stars like our sun
(ScienceNOW, 25 August 2004). The wobbles arise from the back-and-forth
gravitational tugs of planets as they orbit. A team led by astronomers
Michel Mayor and Didier Queloz of the Geneva Observatory in Switzerland
monitored a southern hemisphere star called HD 69830 and saw signs of
two planets, with estimated masses 10 to 15 times that of Earth. The
planets are both baked by the star's heat: They take just 9 days and 31
days to orbit, placing them closer to the star than Mercury is to the
sun.

See: http://sciencenow.sciencemag.org/cgi...ull/2006/517/2