By Xinhua
London : British and Spanish scientists have discovered a possible terrestrial-type planet orbiting a star in the constellation of Leo, science news weibsite Alpha Galileo reported on Wednesday.
A team of astronomers from the Spanish Research Council (CSIC) working with Jean-Philippe Beaulieu, a visiting astrophysicist at University College London (UCL), made the discovery from model predictions of a new exoplanet (extrasolar planet) orbiting a star in the constellation of Leo.
The new planet, dubbed GJ 436c, lies at a distance of 30 light years from the Earth and has a mass five times that of our planet, but is the smallest found to date, according to the astronomers.
Simulations show that the exoplanet orbits its host star (GJ 436) in only 5.2 Earth days, and is thought to complete a revolution in 4.2 Earth days, compared to the Earth’s revolution of 24 hours and full orbit of 365 days.
One full day on the new planet would take four planetary years, or roughly three weeks on Earth.
Current models predict that the new planet is a rocky type and has a radius some 50 percent larger than the Earth, the astronomers said.
The study predicted the presence of a small exoplanet perturbing an inner planet (already known), producing changes on its orbit, the report said, adding that a re-analysis of archival radial velocities also permitted the identification of a signal that perfectly matches the simulations and corresponds to a planet in resonance with the inner one, meaning that for every two orbits of the known planet the new planet completes one.
The study leader Ignasi Ribas from CSIC was quoted as saying “After final confirmation, the new exoplanet will be the smallest found to date. It is the first one to be identified from the perturbations exerted on another planet of the system.”
According to Jean-Philippe Beaulieu, the visiting astrophysicist at UCL Physics and Astronomy, this is the fourth super-Earth planet discovered. “This planet is the hot twin of the frozen super-Earth (OGLE-2005-BLG-390lb) we discovered by microlensing two years ago. Other previously discovered planets of this class are the two hot super-Earths Gl 581b and Gl 876d detected by their Doppler wobble,” he said.
Giovanna Tinetti at UCL Physics and Astronomy who recently calculated the putative properties of this planet, said calculations indicate that the temperature of the planet could be within 127-427 Celsius, but it could locally be as low as 77 Celsius at the poles, depending on the type of atmosphere.
Most of the 280 or so planets discovered to date are gas giants similar to Jupiter, although some with masses below 10 times that of the Earth have already been found. Planets with masses of between one and 10 times the Earth are often dubbed super-Earths.