http://truthufo.blogspot.com/: A planet "habitable" to twenty light-years from Earth

Friday, 22 August 2008

A planet "habitable" to twenty light-years from Earth

Researchers from three laboratories french associated with CNRS, the Geneva Observatory and the Centre for Astronomy Lisbon just detect for the first time an extrasolar planetary system including a type of planet Earth habitable. Situated around the red dwarf star Gl581, 20.5 light years from our planet, this "super-Earth" is the lightest of the 200 extrasolar planets known to date. It is also the first to gain both a liquid or solid surface and a temperature approaching that of Earth.

These common points with our planet can imagine the existence of a possible extra-terrestrial life. This discovery is to appear in the journal Astronomy & Astrophysics.

Artist's view of the planetary system around the red dwarf Gliese 581. The system contains three low mass planets, including a planet 5 times the mass of Earth and probably rocky.
Located in the habitable zone, the water is probably liquid

The star Gl581 is a red dwarf star (very low mass). Located 20.5 light years from Earth, it is among the 100 stars closest to our solar system and its mass is at least a third of that of the Sun. The red dwarfs are prime targets for finding habitable planets. Indeed, these stars are relatively low light, their habitable planets orbit around them, and are then more easily detectable. Moreover, the red dwarf stars are the most numerous of the Galaxy: of the 100 stars closest to us, 80 are part of this family.

The temperature of a planet depends on both the distance from its star, but also its ability to reflect a portion of the light it receives (albedo). The models used by researchers indicate that the average temperature of the extrasolar planet is between 0 and 40 degrees Celsius. These conditions permit the presence of liquid water on its surface. In a very low mass (5 times that of Earth), this planet orbiting the star Gl581 in 13 days. For this weight, the models provide a constitution is rocky (like Earth) or a surface covered by an ocean. The gravity at its surface is 2.2 times that of the Earth's surface, and its radius 1.5 times larger than Earth. By its temperature (which makes it habitable) and its relative proximity to our own solar system (20.5 light-years only), this planet will become the target of future missions dedicated to the search for extra-terrestrial life, including DARWIN with the satellite.

another planet orbiting a 5.4 days around the star Gl581, and the mass of Neptune, had already been discovered in 2005 by the same team. At the same time that the planet habitable, these researchers have also identified a third planet, with a mass 8 times bigger than Earth and orbiting in 84 days around the same star. The Gl581 system is therefore constitute at least 3 planets of less than 15 times the mass of the Earth: the first mass comparable to Neptune and these two super Lands, whose second is at a distance from its star that makes habitable.

For these observations, researchers have used the new spectrograph installed generation HARPS telescope at home by 3.6 metres in diameter at the ESO La Silla, Chile. It is worth noting that 4 of 5 known planets around red dwarf, less than 20 times the mass of Earth, were discovered by the same team Franco-Swiss-Portuguese, using HARPS.