Pakistan Rupee Exchange Rate
American Dollar Exchange Rate
Euro Exchange Rate
(ESO/AP)
Corot-7b orbits 1.6 million miles from its parent star, 23 times closer than Mercury is to the Sun
Astronomers have confirmed that a planet orbiting a distant star has a rocky structure similar to that of Earth, a find that shortens the odds on extraterrestrial life being discovered.
New observations of a planet named Corot-7b, which circles a star 500 light years away in the constellation Monoceros (the Unicorn), have shown that its density is similar to the Earth’s, indicating that it is also a solid, rocky world.
The discovery is important for the prospects of finding life elsewhere in the solar system because Corot-7b is the first exoplanet – a planet beyond our Solar System – orbiting another star that has been confirmed to have the sort of solid structure that might harbour living things.
Although it is unlikely that the planet itself could be home to living organisms because it is so hot — it is so close to its parent star that scientists have likened it to “Dante’s Inferno” — the new research suggests that other rocky worlds are probably common.
Some of these are likely to be in the so-called “Goldilocks zone” — an orbit in which conditions are neither too hot nor too cold, but just right for life.
The discovery of Corot-7b was announced in February, following observations by the Corot planet-hunting space observatory, but while its diameter was shown then to be about 80 per cent larger than the Earth’s, its mass and hence its density could not initially be calculated.
These values have now been worked out from new data collected by the High Accuracy Radial-velocity Planet Searcher (HARPS) instrument at the European Southern Observatory’s La Silla Observatory. The planet’s mass is about five times that of Earth, which means its density is similar to that of our planet.
“This is science at its thrilling and amazing best,” said Didier Queloz, of the Geneva Observatory in Switzerland, who led the research team. “We did everything we could to learn what the object discovered by the Corot satellite looks like and we found a unique system.”
Claire Montou, of the Marseilles Astrophysics Laboratory in France, another member of the team, said the planet’s mass “is the smallest that has been precisely measured for an exoplanet. Moreover, as we have both the radius and the mass, we can determine the density and get a better idea of the internal structure of this planet.”
Details of the planet’s mass and density were announced today at the European Planetary Science Congress in Barcelona, and will be published in the journal Astronomy and Astrophysics.
Corot-7b orbits 1.6 million miles (2.5 million kilometres) from its parent star, which is 23 times closer than Mercury is to the Sun, and this makes the planet exceptionally hot.
“Corot-7b is so close that the place may well look like Dante’s Inferno, with a probable temperature on its ‘day-face’ above 2000C and minus 200C on its night face,” Dr Queloz said. “Theoretical models suggest that the planet may have lava or boiling oceans on its surface. With such extreme conditions this planet is definitively not a place for life to develop.”
The confirmed existence of a planet with a rocky structure and a density like the Earth’s, however, increases the chances that similar worlds with more favourable conditions for life will be found. The Corot probe and Nasa’s Kepler planet-hunting observatory are in orbit looking for such planets.
Alan Boss, of the Carnegie Institution of Washington, who works on Kepler, said: “The evidence is becoming overwhelming that we live in a crowded universe.”
The initial measurements of Corot-7b by the Corot telescope were unable to determine the planet’s mass because this requires precise measurement on the planet’s slight gravitational pull on its star. Corot was incapable of doing this because of “starspots”, similar to our Sun’s sunspots, which blur the signal.
The HARPS instrument has now made further observations of Corot-7b from which astronomers have been able to tease out precise details of the planet’s orbit, mass and density. Link...