* Astronomy

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WASP-8b

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RE: Extrasolar Planets

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Turning Planetary Theory Upside Down

The discovery of nine new transiting exoplanets is announced today at the RAS National Astronomy Meeting (NAM2010). When these new results were combined with earlier observations of transiting exoplanets astronomers were surprised to find that six out of a larger sample of 27 were found to be orbiting in the opposite direction to the rotation of their host star - the exact reverse of what is seen in our own Solar System. The new discoveries provide an unexpected and serious challenge to current theories of planet formation. They also suggest that systems with exoplanets of the type known as hot Jupiters are unlikely to contain Earth-like planets.
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Fourteen exoplanets have been discovered since the year began while the figure for 2009 was 84, said eminent astronomer Malcolm Longair, of the Cavendish Laboratory in Cambridge.
Exoplanets are those planets that lie outside the solar system. There are billions of stars in our galaxy and a significant percentage of these have planets orbiting them. "As of February 27, 429 exoplanets were discovered, some of these by Nasas Hubble Space Telescope and the Spitzer Infrared Observatory", he said at the Tata Institute of Fundamental Research.
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L'activité de certaines étoiles perturberait la détection d'exoTerre

Des chercheurs du Laboratoire d'Astrophysique de Grenoble (LAOG : INSU-CNRS, Université Joseph Fourier, Observatoire des Sciences de l'Univers de Grenoble) viennent de réaliser une étude sur le rôle que peut avoir l'activité d'une étoile de type solaire, dans la détection d'exoplanète de type exoTerre. Si les taches et plage de l'étoile pendant sa période d'activité calme ne gêneraient pas la détection d'une exoTerre se situant dans une zone dite d'habitabilité, par contre les mouvements convectifs compromettent la détection de ce type d'exoplanète. Il est donc nécessaire de développer de nouveaux moyens de mesures et d'analyse pour dépasser cette limitation. Ce résultat fera l'objet de deux articles dans Astronomy and Astrophysics.
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An era of planet discovery is dawning that will see thousands of new worlds identified in the next few years, some of which may harbour life.
More than 400 "exoplanets" orbiting stars beyond the Sun have been catalogued since the first were discovered in 1991.
A report from the Institute of Physics today predicted that in the coming years "the number will rise to thousands".
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Title: Clouds in the atmospheres of extrasolar planets. I. Climatic effects of multi-layered clouds for Earth-like planets and implications for habitable zones
Authors: D. Kitzmann, A.B.C. Patzer, P. von Paris, M. Godolt, B. Stracke, S. Gebauer, J.L. Grenfell, H. Rauer

The effects of multi-layered clouds in the atmospheres of Earth-like planets orbiting different types of stars are studied. The radiative effects of cloud particles are directly correlated with their wavelength-dependent optical properties. Therefore the incident stellar spectra may play an important role for the climatic effect of clouds. We discuss the influence of clouds with mean properties measured in the Earth's atmosphere on the surface temperatures and Bond albedos of Earth-like planets orbiting different types of main sequence dwarf stars.

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Title: Mass-radius relationships for exoplanets
Authors: Damian Swift, Jon Eggert, Damien Hicks, Sebastien Hamel, Kyle Caspersen, Eric Schwegler, Gilbert Collins, Graeme Ackland

For planets other than Earth, and in particular for exoplanets, interpretation of the composition and structure depends largely on a comparison of the mass and radius with the composition expected given their distance from the parent star. The composition implies a mass-radius relation for different layers within the planet, which is based heavily on equations of state calculated from electronic structure theory and measured experimentally on Earth. We summarise current techniques for predicting and measuring equations of state, and calculate mass-radius relations for key materials for which the equation of state is reasonably well established, and for Fe-rock combinations. The relations are compared with the observed masses and radii of planets and exoplanets, broadly supporting recent inferences about exoplanet structures. CoRoT-7b probably has a rocky mantle over an Fe-based core. The core is likely to be proportionately smaller than the Earth's. GJ 1214b lies between the mass-radius curves for H_2Oand CH_4, suggestive of an 'icy' composition with a relatively large core or a relatively large proportion of H_2O. CoRoT-2b is less dense than the hydrogen relation, which could be explained by an anomalously high degree of heating or by higher than expected opacity in the outer regions of its atmosphere. HAT-P-2b is slightly denser than the mass-radius relation for hydrogen, suggesting the presence of a significant amount of matter of higher atomic number. The pressure at the center of CoRoT-7b is probably close to 0.8 TPa, which is accessible by experiments at large laser facilities. The center of HAT-P-2b is probably at a pressure in excess of 210 TPa, in the range of future experiments being planned for the National Ignition Facility.

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15 Fascinating Planets Outside Our Solar System

Exoplanets or "extrasolar planets" are planets found outside our solar system. They are designated by affixing a lowercase letter, starting from "b" towards "z" depending on order of discovery, to their parent star's Flamsteed designation or catalogue numbers.
When PSR1257 + 12 B and PSR1257 + 12 C (they used uppercase letters for these very first ones because they did not yet use the current nomenclature), and later 51 Pegasi b, the first confirmed exoplanets were discovered in the early 1990's, they were hailed as the most significant breakthroughs in the field of Astronomy since the Copernican Revolution and caused an uproar in the scientific community, and revived hopes of finding Earth-like planets and perhaps life outside the Solar System.
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Astronomers say they are on the verge of finding planets like Earth orbiting other stars, a key step in determining if we are alone in the universe.
A top NASA official and other leading scientists say that within four or five years they should discover the first Earth-like planet where life could develop, or may have already. A planet close to the size of Earth could even be found sometime this year if preliminary hints from a new space telescope pan out.
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