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TOPIC: Extrasolar Planets


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RE: Extrasolar Planets
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Planet hunters searching for planets suitable for life will likely find them first around low-mass stars because it's technically easier than finding such planets around hotter, more massive stars, researchers predict.
But Earth-like planets around stars smaller than our sun won't be liveable for long, according to a study led by Rory Barnes, a research associate with The University of Arizona's Lunar and Planetary Laboratory. Such planets can face "tidal extinction" within about a billion years.
Barnes will talk about it at a departmental colloquium at 3:30 p.m. Tuesday, Dec. 2. His talk, titled "Planetary Habitability Near Low-Mass Stars," will be in Room 308 of the Kuiper Space Science Building.

A star only a quarter-to-a-tenth as massive as our sun is also cooler than our sun, so the "habitable zone" for its planets where water is liquid also will be closer in...

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Exoplanets
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Hidden alien moons that could harbour life can be revealed by the wobbles of their planets.
Almost all the 30 known exoplanets that sit within the habitable zone of their stars are gas giants.

"But they might have rocky, possibly Earth-like moons" - David Kipping of University College London.

His calculations, which will appear in Monthly Notices of the Royal Astronomical Society, show that such moons would reveal their presence when the planet passes in front of its star as viewed from Earth. A moon would induce a wobble in the planet's orbit, so the planet's position and velocity would differ slightly on each transit. Existing telescopes could detect an Earth-mass moon around a Neptune-mass gas planet.

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Exoplanets finally come into view
The list of more than 300 exoplanets now includes actual pictures, two groups report in the journal Science.
The first visible-light images of an exoplanet have been taken of a planet 25 light-years away.
The planet is believed to be the coolest, lowest-mass object ever seen outside our own galactic neighbourhood.
In a separate study, an exoplanetary system, comprising three planets, has been directly imaged, circling a star in the constellation Pegasus.

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A planet on a very oblique orbit?
The trajectory of a planet is generally located in the same plane as the equator of the star around which it orbits. This is the case for the planets of the Solar system as for the majority of known extra-solar planets. A recently detected planet, named XO-3b, could however be on a very oblique orbit, which would make it pass almost over the poles of its star. This large obliquity was measured thanks to recent observations at the Haute-Provence Observatory by a team of European astronomers. This result, to be confirmed by further observations, could be the signature of a particular past event during the life of this planet, such as a strong gravitational interaction with another star.

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Habitable worlds may hide in gas giants' wake
Habitable planets may be lurking in the wake of Jupiter-like planets as they orbit distant stars.
When a gas giant coalesces from the swirling nebula of gas and dust surrounding a young star, the planet's gravity forms a wake ahead and behind it, concentrating enough matter there for it to clump together and form smaller, rocky planets like Earth. That's according to simulations led by Wladimir Lyra of the Uppsala Astronomical Observatory in Sweden. Objects born in Jupiter's wake may have merged to form the planet Saturn, which was then nudged into its current position by the gravity of other planets, the team says

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Strange weather on 'hot Jupiters' explained
Speedy jet streams can carry warm air from the sunny side to the dark side.
Though scientists have yet to find alien life on distant exoplanets, much about those planets certainly seems alien especially the weather.
Now researchers have developed a model that can explain some of the bizarre weather patterns seen on other worlds.


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Computer simulations of the atmospheric circulation on Jupiter-like planets around other stars can explain temperature observations of these planets and shed light on the exotic weather experienced by these far-away worlds.
Approximately 300 planets have been discovered around other stars, and for most of those planets, scientists know little more than the mass and orbital properties of the planet. However, for a handful of the brightest planets, temperatures have been inferred from observations carried out with spacebased platforms such as NASA's Spitzer Space Telescope. Those observations and the computer simulations used to explain them, hint at weather patterns truly alien to our Earth-based experience.
Adam Showman of The University of Arizona led a study explaining how a global atmospheric circulation driven by the dayside heating and nightside cooling can drive weather on the so-called "hot Jupiters" Jupiter-like gaseous giant planets that orbit extremely close to their stars.

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Searching for other worlds
So are we alone in this big universe? While probably not on most peoples minds, given the more urgent matters of daily life on planet Earth, a sector of humanity has been on a quest to know if other worlds out there may be inhabited. This is by far not a new idea. At least some astronomers in the 19th century were convinced that there are, or should be, other inhabited planets.

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COROT-exo-3b
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The European planet-hunter Corot has spotted an object orbiting a star that is quite unlike anything seen before.
It is about the size of Jupiter, but packs more than 20 times the mass.

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