Posted on 01/01/2008 11:04:56 AM PST by KevinDavis
For the first time, the scattered light from a planet orbiting a distant star has been detected by an international team of astronomers led by Prof. Svetlana Berdyugina (ETH Zurich). Similar to how polaroid sunglasses filter away reflected sunlight to reduce glare, the scientists have used tricks with polarized light to enhance the faint reflected starlight "glare" from an extrasolar planet. This allowed them to trace directly the orbit of the planet and infer the size of its swollen atmosphere, in contrast to other exoplanets detected by various indirect methods.
The exoplanet circles a red dwarf star, called HD189733, in the constellation Vulpecula which lies about 60 light years from the Earth. The planet, known as HD189733b, was discovered two years ago via Doppler spectroscopy and photometric transits. It is so close to its central star that its atmosphere expands from the heat. Astronomers have, until now, never seen light reflected from an exoplanet although they deduce from other observations that this one probably resembles a "hot Jupiter". Unlike Jupiter, it orbits its star in a couple of days rather than the 12 years it takes Jupiter to make one orbit of the Sun.
The team, consisting of Svetlana Berdyugina (ETH Zurich & Tuorla Observatory), Andrei Berdyugin and Vilppu Piirola (Tuorla Observatory), and Dominique Fluri (ETH Zurich), used the remotely controlled 60cm KVA telescope on La Palma, Spain, to obtain polarimetric measurements of the star and its planet. These measurements demonstrate that the scattering atmosphere most probably consists of particles smaller than half a micron, such as atoms, molecules, perhaps water vapor which was recently suggested for this planet, or even tiny dust grains. Such particles effectively scatter the light in the blue - in exactly the same way as in the Earth's atmosphere. The researchers are also able for the first time to recover the shape and orientation of the planet's orbit as seen on the sky plane, i.e. obtain an "image" of the orbit (see figure on the right).
The polarimetric detection of the reflected light from exoplanets opens new vast opportunities for exploring physical conditions in their atmospheres as well as for determining radii and true masses, and hence densities, of non-transiting planets.
No intelligent life there though.
The future ground based telescopes are the death knell of our beloved Hubbel but progress is a good thing.
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Again the question begs, do we really need to spend the money servicing the Hubble???
NASA's Hubble Space Telescope took this snapshot of Mars 11 hours before the planet made its closest approach to Earth. The two planets are 34,648,840 miles (55,760,220 km) apart. This image was made from a series of exposures taken between 6:20 p.m. and 7:12 p.m. EDT Aug. 26 with Hubble's Wide Field and Planetary Camera 2. Photo credit: NASA/J. Bell (Cornell U.) and M. Wolff (SSI).Hubble's Eye on MarsThe Hubble images are the sharpest views of Mars ever taken from Earth. They reveal surface details as small as 17 miles (24 km) across. Though NASA's Mars-orbiting spacecraft can photograph the Red Planet in much finer detail, Hubble routinely serves as a "weather satellite" for tracking atmospheric changes on Mars and for probing its geology on a global scale.
USGS Astrogeology Hot Topics
Wednesday, August 27, 2003
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