Exoplanets large and small, hot and cold...

[Rick]

Gliese 581d 'too crusty' for civilisation to arise

Astroplanet boffins in America say that humanity may not, as had been expected, soon be the target of an interstellar assault from alien civilisations unwisely enraged by Web-2.0 teenybopper portal Bebo. It appears that the planet Gliese 581d - which might have mounted an invasion of the Solar System as soon as 2049 - cannot after all support life.

More: http://www.theregister.co.uk/2009/06/11/gliese_581_not_habitable_after_all/

[mickw]

Planets orbit stars in the same direction that the stars rotate. They all do. Except one.

A newfound planet orbits the wrong way, backward compared to the rotation of its host star. Its discoverers think a near-collision may have created the retrograde orbit, as it is called.

The star and its planet, WASP-17, are about 1,000 light-years away. The setup was found by the UK's Wide Area Search for Planets (WASP) project in collaboration with Geneva Observatory. The discovery was announced today but has not yet been published in a journal.

More:   http://www.space.com/scienceastronomy/090812-backward-planet.html

[Rick]

Astronomers have discovered the first planet that orbits in the opposite direction to the spin of its star.

Planets form out of the same swirling gas cloud that creates a star, so they are expected to orbit in the same direction that the star rotates.

The new planet is thought to have been flung into its "retrograde" orbit by a close encounter with either another planet or with a passing star.

More: http://news.bbc.co.uk/1/hi/sci/tech/8197683.stm

[Rick]

Astronomers have spotted what they claim is the first exoplanet in a retrograde orbit around a star - a bloated body which is also the "least-dense planet currently known".

Dubbed WASP-17b, the body measures 1.5-2 Jupiter radii but weighs in at just half its mass, meaning it's about a dense as polystyrene and "if you could place it in a bathtub, it would bob like a beach ball", as New Scientist nicely puts it.

More: http://www.theregister.co.uk/2009/08/13/retrograde_exoplanet/

[mickw]

One of the smallest exoplanets yet discovered has just been confirmed as a rocky world, scientists announced.

The planet, called CoRoT-7b, is the first planet beyond our solar system with a proven density similar to Earth's, astronomers say. Most known exoplanets are large gas giants like Jupiter.

"We have indications that other exoplanets could be rocky, but it's the first time that the density of such a planet has been measured," said study team member Claire Moutou of the Laboratoire d'Astrophysique de Marseille in France. "We are really sure it's rocky."

More:   http://www.space.com/scienceastronomy/090916-rocky-exoplanet.html

[Carole]

Astronomers confirm first planet made of rock discovered outside our solar system

Astronomers have found a rocky planet in a distant solar system, in a discovery that raises hopes of finding alien life.
Corot 7b is similar in size to Earth, but daytime temperatures of 1,500C mean it is far
too hot for anything to flourish there.
However the discovery suggests there may be planets with more hospitable conditions throughout the galaxy.


Read more: http://www.dailymail.co.uk/sciencetech/article-1213942/More-proof-Astronomers-confirmed-planet-rock--raising-prospect-alien-life.html#ixzz0RJ5zP9Tq

[mickw]

On Earth, strange things, including frogs and fish, sometimes fall from the sky, but on a distant extrasolar planet, the weather could be even weirder: When a front moves in, small rocks rain down on the surface, a new study suggests.

The exoplanet, COROT-7b, was discovered in February by the COROT space telescope launched by the French and European space agencies. Last month is became the first planet outside our solar system to be confirmed as a rocky body — most other known exoplanets are gas giants.

The planet is nearly twice the size of Earth and about five times the mass of our world. Calculations have indicated it has a density about that of Earth's, which means it is likely made up of silicate rocks, just as Earth's crust is.

The planet is likely much less hospitable to life though, as it is only about 1.6 million miles (2.6 million km) away from its parent star — 23 times closer than Mercury sits to the sun.

More:   http://www.space.com/scienceastronomy/091001-rock-rain.html

[Rick]

Astronomers have announced a haul of planets found beyond our Solar System.

The 32 "exoplanets" ranged in size from five times the mass of Earth to 5-10 times the mass of Jupiter, the researchers said.

They were found using a very sensitive instrument on a 3.6m telescope at the European Southern Observatory's La Silla facility in Chile.

The discovery is exciting because it suggests that low-mass planets could be numerous in our galaxy.

More: http://news.bbc.co.uk/1/hi/sci/tech/8314581.stm

[mickw]

A young star observed by the Spitzer Space Telescope appears to be home to a wild – and young – planetary system that shares some of the frenetic dynamics thought to have shaped the early years of our own solar system.

The Spitzer observations suggest young planets circling the star are disturbing smaller comet-like bodies, causing them to collide and kick up a huge halo of dust.

The star, called HR 8799, became one of the first of two stars with planets that were directly imaged from Earth in November 2008. Ground-based telescopes at the W.M. Keck Observatory and the Gemini Observatory, both in Hawaii, took images of three planets orbiting in the far reaches of the system. Each of the three distant worlds is roughly 10 times the mass of Jupiter.

HR 8799 is younger and more massive than our sun, which is more than 4.5 billion years old and more than 300,000 times the mass of Earth. It is about 129 light-years from Earth, so scientists weren't sure if Spitzer would be able to snap a picture of its debris disk. But to their amazement, it succeeded.

More:   http://www.space.com/scienceastronomy/091110-st-chaotic-planet-system.html

[mickw]

Astronomers have discovered hundreds of Jupiter-like planets in our galaxy. However, a handful of the planets found orbiting distant stars are more Earth-sized. This gives hope to astrobiologists, who think we are more likely to find life on rocky planets with liquid water.

The rocky planets found so far are actually more massive than our own. Dimitar Sasselov, professor of astronomy at Harvard University, coined the term "Super-Earths" to reflect their mass rather than any superior qualities.

But Sasselov says that these planets – which range from about 2 to 10 Earth masses – could be superior to the Earth when it comes to sustaining life.

More:   http://www.space.com/scienceastronomy/091201-am-super-earths-alien-life.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+spaceheadlines+%28SPACE.com+Headline+Feed%29

[Rick]

Astronomers have published an image of the coolest planet outside our solar system that has been pictured directly.

The new find is more similar to our own Solar System than prior pictured exoplanets, in terms of the parent star's type and the planet's size.

However, the surface temperature is a scorching 280-370C, and could still prove to be a brown dwarf star.

More: http://news.bbc.co.uk/1/hi/sci/tech/8393607.stm

[Rick]

Planet-hunters have discovered two "super-Earths" orbiting two nearby Sun-like stars.

These rocky planets are larger than the Earth but much smaller than ice giants such as Uranus and Neptune.

Scientists say the discoveries are a step towards finding potentially habitable planets - smaller planets that are comparable to the Earth.

More: http://news.bbc.co.uk/1/hi/sci/tech/8414476.stm

[mickw]

WASHINGTON — The list of known exoplanets in the galaxy just got bigger, thanks to the first observations of NASA's Kepler space telescope, which found five new lightweight worlds orbiting distant stars.

"I would like to announce today the discovery of five exoplanets by Kepler," said Kepler science director William Borucki of NASA's Ames Research Center in Moffett Field, Calif., here today at the 215th meeting of the American Astronomical Society.

The planet-hunting Kepler, which hopes to discover alien Earths, also found an odd object orbiting a star and is measuring the quakes that ripple across stellar surface.

The five newfound planets are all much larger than the Earth-sized bodies Kepler was designed to find, with one coming in at around the size of Neptune, and the other four measuring larger than Jupiter.

More:   on Space.Com

[mickw]

A rocky extrasolar planet known to have wild temperature extremes may also covered in volcanoes.

The planet, CoRoT-7b was confirmed to be orbiting a star some 480 light-years away in October. While it has a rocky surface, it is unlikely to harbor life because it sits so close to its parent star – temperatures may be as high as 4,000 degrees Fahrenheit (2,200 degrees Celsius) on its day side and as low as minus 350 F (minus 210 C) on its night side.

New evidence suggest that this forbidding world is even more unfriendly to life: Unless the planet's orbit is almost perfectly circular, it could also be undergoing fierce volcanic eruptions, astronomers announced here at the 215th meeting of the American Astronomical Society

More on Space.Com

[mickw]

For the first time, astronomers have directly detected the light signature of a planet orbiting an almost sun-like star. This signature can tell scientists the chemical makeup of the planet, which can help them understand how it formed. in the future these signatures could be used to look for signs of  life on other planets.

The planet is a giant, about 10 times as massive as Jupiter, and it orbits between two other giants around a star similar to our sun in a scaled-up version of our own solar system.

The three giant companions were detected in 2008 and range in mass from seven to 10 times that of Jupiter, with orbits between 20 and 70 times as far from their host star as Earth is from the sun. The system also features two belts of smaller objects, similar to the asteroid and Kuiper belts around our sun. The system's star is about 1.5 times as massive as the sun.

More:   a short link 8o)