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Astronomers spot dozens of 'super-Earths'
(Agencies)
Updated: 2008-06-16 22:57 All of the 45 exoplanets unveiled Monday have masses four to 30 times greater than Earth's, and orbits at least seven times shorter, meaning they are much closer to their respective stars and thus easier to spot. The planets found circling HD 40307 have 4.2, 6.7, and 9.4 times the mass of the Earth, and orbit the star in periods of 4.3, 9.6, and 20.4 days, respectively. At the same conference, astronomers announced the discovery of two other planetary systems, also with the HARPS spectrograph. In one, a super-Earth orbits the star HD 181433 every 9.5 days. The same star also hosts a huge, Jupiter-like planet that circles every three years. The second system contains a fiery planet 22 times the size of Earth that circumnavigates its sun every four days, and a Saturn-like sphere with a three-year orbit. "It is probable that there are many other planets present -- not only super-Earths, but Earth like-planets that we cannot yet detect," said Stephane Udry, also a researcher at the Geneva Observatory. Planets are formed from a disc of gas and dusty debris left over from the creation of a star. Just how long this process takes is still a matter of debate. Earth is believed to be about 4.5 billion years old, and the Sun about 100 million years older. |
