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Survey Suggests Earth-Sized Planets Are Common

Copyright NASA

Nearly one in four stars similar to the sun may host planets as small as Earth, according to a new study funded by NASA and the University of California.

The study is the most extensive and sensitive planetary census of its kind. Astronomers used the W.M. Keck Observatory in Hawaii for five years to search 166 sun-like stars near our solar system for planets of various sizes, ranging from three to 1,000 times the mass of Earth. All of the planets in the study orbit close to their stars. The results show more small planets than large ones, indicating small planets are more prevalent in our Milky Way galaxy.

“We studied planets of many masses — like counting boulders, rocks and pebbles in a canyon — and found more rocks than boulders, and more pebbles than rocks. Our ground-based technology can’t see the grains of sand, the Earth-size planets, but we can estimate their numbers,” said Andrew Howard of the University of California, Berkeley, lead author of the new study. “Earth-size planets in our galaxy are like grains of sand sprinkled on a beach — they are everywhere.”

The study appears in the Oct. 29 issue of [...]

Out of Whack Planetary System Offers Clues to a Disturbed Past

Copyright NASA

Astronomers are reporting today the discovery of a planetary system way out of tilt, where the orbits of two planets are at a steep angle to each other. This surprising finding will impact theories of how multi-planet systems evolve, and it shows that some violent events can happen to disrupt planets’ orbits after a planetary system forms, say researchers.

“The findings mean that future studies of exoplanetary systems will be more complicated. Astronomers can no longer assume all planets orbit their parent star in a single plane,” says Barbara McArthur of The University of Texas at Austin’s McDonald Observatory.

McArthur and her team used data from the Hubble Space Telescope, the giant Hobby-Eberly Telescope, and other ground-based telescopes combined with extensive modeling to unearth a landslide of information about the planetary system surrounding the nearby star Upsilon Andromedae.

McArthur reported these findings in a press conference today at the 216th meeting of the American Astronomical Society in Miami, along with her collaborator Fritz Benedict, also of McDonald Observatory, and team member Rory Barnes of the University of Washington. The work also will be published in the June 1 edition of the Astrophysical Journal.

For just over a [...]

Ground-Based Telescope Images Three Exoplanets

Copyright NASA

Astronomers have snapped a picture of three planets orbiting a star beyond our own using a modest-sized telescope on the ground. The surprising feat was accomplished by a team at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., using a small portion of the Palomar Observatory’s Hale Telescope, north of San Diego.

The planets had been imaged previously by two of the world’s biggest ground-based telescopes — one of the two 10-meter (33-foot) telescopes of W.M. Keck Observatory and the 8.0-meter (26-foot) Gemini North Observatory, both on Mauna Kea in Hawaii. The planets, which orbit the star HR 8799, were among the very first to be directly imaged, a discovery announced in Nov. of 2008.

The new image of the planets, taken in infrared light as before, was captured using just a 1.5-meter-diameter (4.9-foot) portion of the Hale telescope’s mirror. The astronomy team took painstaking efforts to push current technology to the point where such a small mirror could be used. They combined two techniques — adaptive optics and a coronagraph — to minimize the glare from the star and reveal the dim glow of the much fainter planets.

The picture is online at http://www.nasa.gov/topics/universe/features/exoplanet20100414-a.html.

“Our technique could [...]

COROT discovers its first exoplanet and catches scientists by surprise

corot-discovers-its-first-exoplanet-and-catches-scientists-by-surprise

Copyright ESA

COROT has provided its first image of a giant planet orbiting another star and the first bit of ‘seismic’ information on a far away, Sun-like star, with unexpected accuracy.

The unanticipated level of accuracy of this raw data shows that COROT will be able to see rocky planets – perhaps even as small as Earth – and possibly provide an indication of their chemical composition.

COROT, a CNES project with ESA participation, is a mission with a dual goal. It is the first space mission dedicated entirely to the search of extra-solar planets. It provides a wide-field survey of planets like our own at an unprecedented level of accuracy. It is also making the most comprehensive study ever of the interior of stars other than our Sun. Both objectives are achieved by analysing the behaviour of light emitted by a target star.

An exoplanet is detected by COROT due to a sudden decrease in the intensity of light or the ‘light curve’ of a parent star when a planet transits in front of it.

The study of stellar interiors – or ‘asteroseismology’ – is carried out by analysing the oscillations in the light curve of the star. The [...]