Corot telescope in exoplanet haul

14 June 2011 Last updated at 17:21 GMT Corot and other telescopes measure the light change when a planet "transits" Ten new planets outside our Solar System have been spotted by the French-led Corot satellite, bringing the total number of known exoplanets to 561.

They include one planet orbiting an unusually young star, and two Neptune-sized planets orbiting the same star.

Corot, launched in 2006, spots planets by measuring the tiny dip in stellar light that occurs when planets pass between the stars and the Earth.

It has now added 23 planetary systems to the ever-growing roster.

Corot, operated by France's space agency CNES, was launched in late 2006. It went into orbit shortly before Kepler, a similar mission by the American space agency Nasa.

Originally scheduled to run only until mid-2008, its remit has since been extended to 2013.

It has since established itself not only as a planet-hunter but also a precise instrument for astroseismology - the study of the composition of stars based on the light they emit.

In the latest list of 10 exoplanet finds, seven are so-called "hot Jupiters", gas giant planets similar to our own Jupiter but far closer to their host star - completing their orbits in just days.

Two more orbit the star Corot-24, with diameters equal to and about 1.4 times that of Neptune, completing their orbits in five and 12 days, respectively.

One of the hot Jupiter planets orbits the star Corot-18, which is believed to be just 600 million years old. This is of particular interest to astrophysicists because there is much to be learned from the earliest stages of planet formation.

"If we want to understand the conditions in which planets form, we need to catch them within the first few hundred million years," said Suzanne Aigrain, a University of Oxford astrophysicist who is part of the Corot team.

"In the case of Corot-18, different ways of determining the age give different results, but it's possible that the star might be only a few tens of millions of years old. If this is confirmed, then we could learn a lot about the formation and early evolution of hot gas giant planets by comparing the size of Corot-18b to the predictions of theoretical models."

1. 4-colour CCD camera and electronics: Captures and analyses starlight2. Baffle: Works to shield the telescope from extraneous light3. Telescope: A 30cm mirror; it views the star fields4. Proteus platform: Contains communication equipment, temperature controls and direction controls5. Solar panel: Uses the Sun's radiation to power the satellite

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Murky exoplanet 'could host life'

17 May 2011 Last updated at 10:22 GMT The Gliese star hosts four confirmed planets and may host as many as six A red dwarf star 20 light-years away is again providing hints that it hosts the first definitively habitable planet outside our Solar System.

The planet Gliese 581d is at the colder outer edge of the "Goldilocks zone" in which liquid water can be sustained.

Now a study in Astrophysical Journal Letters suggests its atmosphere may keep things warm enough for water.

The solar system also hosts another contender for habitability, unconfirmed planet Gliese 581g announced in 2010.

However, the existence of that planet has since been called into question.

Gliese 581d is less controversial; it was discovered along with the planet Gliese 581c in 2007, occupying the outer and inner edges of the Goldilocks zone, respectively.

Gliese 581c was soon determined to be too close to its host star to sustain water, with a surface temperature exceeding 1,000C.

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With future generations of telescopes, we'll be able to search for life on Gliese 581d directly”

End Quote Robin Wordsworth Institut Pierre Simon Laplace Conversely, the outlying planet 581d - with a mass about six times that of the Earth and twice its size - was initially taken to be too cold to have liquid water.

Now, French researchers have run computer simulations of the planet's atmosphere, arguing that it is likely to contain high concentrations of carbon dioxide.

They contend that conditions could be suitable for oceans of liquid water as well as clouds and rainfall.

However, Gliese 581d's denser air and dim red light from its host star would make for a murky environment that would be toxic to humans.

Robin Wordsworth, a member of the team from the Institut Pierre Simon Laplace in Paris, said that the findings were further evidence that the sheer variety of planets and environments far outpaced that which we see in our own Solar System.

Dr Wordsworth said that the simulations are tantamount to a first definitive claim for a habitable exoplanet.

"This discovery is important because it's the first time climate modellers have proved that the planet is potentially habitable, and all observers agree that the exoplanet exists," he told news agency PA.

"The Gliese system is particularly exciting to us as it's very close to Earth, relatively speaking. So with future generations of telescopes, we'll be able to search for life on Gliese 581d directly."

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