Scientists announce Planet bounty
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Posted 19 October 2009 - 03:56 PM
Astronomers have announced a haul of planets found beyond our Solar System. The 32 "exoplanets" ranged in size from five times the mass of Earth to 5-10 times the mass of Jupiter, the researchers said. They were found using a very sensitive instrument on a 3.6m telescope at the European Southern Observatory's La Silla facility in Chile.
The discovery is exciting because it suggests that low-mass planets could be numerous in our galaxy. "From [our] results, we know now that at least 40% of solar-type stars have low-mass planets. This is really important because it means that low-mass planets are everywhere, basically," explained Stephane Udry from Geneva University, Switzerland.
"What's very interesting is that models are predicting them, and we are finding them; and furthermore the models are predicting even more lower-mass planets like the Earth."
The discovery now takes the number of known exoplanets - planets outside our Solar System - to more than 400. These have been identified using a range of astronomical techniques and telescopes, but this latest group was spotted as a result of observations made with the Harps spectrometer at La Silla.
The High Accuracy Radial Velocity Planet Searcher instrument employs what is sometimes called the "wobble technique". This is an indirect method of detection that infers the existence of orbiting planets from the way their gravity makes a parent star appear to twitch in its motion across the sky.
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