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HD 189733 b
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Title: Secondary radio eclipse of the transiting planet HD 189733 b: an upper limit at 307-347 MHz
Authors: A. M. S. Smith, A. Collier Cameron, J. Greaves, M. Jardine, G. Langston, D. Backer

We report the first attempt to observe the secondary eclipse of a transiting extra-solar planet at radio wavelengths. We observed HD 189733 b with the Robert C. Byrd Green Bank Telescope of the NRAO over about 5.5 hours before, during and after secondary eclipse, at frequencies of 307 - 347 MHz. In this frequency range, we determine the 3-sigma upper limit to the flux density to be 81 mJy. The data are consistent with no eclipse or a marginal reduction in flux at the time of secondary eclipse in all subsets of our bandwidth; the strongest signal is an apparent eclipse at the 2-sigma level in the 335.2 - 339.3 MHz region. Our observed upper limit is close to theoretical predictions of the flux density of cyclotron-maser radiation from the planet.

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Never mind whether there is life on Mars, is there life on planet HD 189733b? That is the question raised by the discovery of some of the building blocks of life on one of the closest known planets orbiting a star other than our own sun.
Astronomers said yesterday they have detected water and carbon dioxide key signs of life in the atmosphere of HD 189733b, which orbits a star 63 light years away from Earth in the constellation Vulpecula.


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Title: The extrasolar planet atmosphere and exosphere: Emission and transmission spectroscopy
Authors: Giovanna Tinetti (1,2), Jean-Philippe Beaulieu (2,3) ((1) University College London, Gower street, London WC1E 6BT, UK, (2) HOLMES collaboration, (3) Institut d'Astrophysique de Paris, 98bis Boulevard Arago, PARIS, France.)

We have entered the phase of extrasolar planets characterisation, probing their atmospheres for molecules, constraining their horizontal and vertical temperature profiles and estimating the contribution of clouds and hazes. We report here a short review of the current situation using ground based and space based observations, and present the transmission spectra of HD189733b in the spectral range 0.5-24 microns.

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HD 189733b
HD 189733b

This type of observation is best done for planets with orbits tilted edge-on towards Earth. They routinely pass in front of and then behind their parent stars, phenomena known as eclipses. The planet HD 189733b passes behind its companion star once every 2.2 days. This allows an opportunity to subtract the light of the star alone (when the planet is blocked) from that of the star and planet together prior to eclipse), thus isolating the emission of the planet alone and making a chemical analysis of its day-side atmosphere possible.
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The NASA/ESA Hubble Space Telescope has discovered carbon dioxide in the atmosphere of a planet orbiting another star. This is an important step along the trail of finding the chemical biotracers of extraterrestrial life, as we know it.

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NASA's Hubble Space Telescope has discovered carbon dioxide in the atmosphere of a planet orbiting another star. This is an important step along the trail of finding the chemical biotracers of extraterrestrial life as we know it.
The Jupiter-sized planet, called HD 189733b, is too hot for life. But the Hubble observations are a proof-of-concept demonstration that the basic chemistry for life can be measured on planets orbiting other stars. Organic compounds can also be a by-product of life processes, and their detection on an Earth-like planet may someday provide the first evidence of life beyond Earth.

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Carbon dioxide, one of the telltale signs that a planet may be able to support life, has been spotted in the atmosphere of a gas giant orbiting a star 63 light years from Earth.
Although there's no way that this particular planet could support life, being able to spot carbon dioxide in its atmosphere offers hope for probing the atmospheres of planets more like Earth and so bolstering the search for life outside the Solar System.

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Title: A New Atmospheric Model for HD 189733 b
Authors: Jonathan Langton, Gregory Laughlin

We have developed a new two-dimensional hydrostatically-balanced isobaric hydrodynamic model for use in simulation of exoplanetary atmospheres. We apply this model to the infrared photosphere of the hot Jupiter HD 189733 b, for which an excellent 8-micron light curve has been obtained. For reasonable parameter choices, the results of our model are consistent with these observations. In our simulations, strongly turbulent supersonic flow develops, with wind speeds of approximately 5 km/s. This flow geometry causes chaotic variation of the temperature distribution, leading to observable variations in the light curve from one orbit to the next.

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Title: Transits and secondary eclipses of HD 189733 with Spitzer
Authors: Eric Agol, Nicolas B. Cowan, James Bushong (UW), Heather Knutson, David Charbonneau (CfA), Drake Deming (GSFC), Jason H. Steffen (Fermilab)

We present limits on transit timing variations and secondary eclipse depth variations at 8 microns with the Spitzer Space Telescope IRAC camera. Due to the weak limb darkening in the infrared and uninterrupted observing, Spitzer provides the highest accuracy transit times for this bright system, in principle providing sensitivity to secondary planets of Mars mass in resonant orbits. Finally, the transit data provides tighter constraints on the wavelength- dependent atmospheric absorption by the planet.

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Astronomers Detect First Organic Molecule on an Exoplanet
A team of astronomers led by Mark Swain of NASA's Jet Propulsion Laboratory, Pasadena, Calif., has made the first detection ever of an organic molecule in the atmosphere of a Jupiter-sized planet orbiting another star. The breakthrough, made with NASA's Hubble Space Telescope, is an important step in eventually identifying signs of life on a planet outside our solar system.
The molecule found by Hubble is methane, which under the right circumstances can play a key role in prebiotic chemistry - the chemical reactions considered necessary to form life as we know it.

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