* Astronomy

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RE: Planet Hunting

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Title: Detecting Life-bearing Extra-solar Planets with Space Telescopes
Authors: Steven V. W. Beckwith

One of the promising methods to search for life on extra-solar planets (exoplanets) is to detect life's signatures in their atmospheres. Spectra of exoplanet atmospheres at the modest resolution needed to search for oxygen, carbon dioxide, water, and methane will demand large collecting areas and large diameters to capture and isolate the light from planets in the habitable zones around the stars. For telescopes using coronagraphs to isolate the light from the planet, each doubling of telescope diameter will increase the available sample of stars by an order of magnitude, indicating a high scientific return if the technical difficulties of constructing very large space telescopes can be overcome. For telescopes detecting atmospheric signatures of transiting planets, the sample size increases only linearly with diameter, and the available samples are probably too small to guarantee detection of life-bearing planets. Using samples of nearby stars suitable for exoplanet searches, this paper shows that the demands of searching for life with either technique will require large telescopes, with diameters of order 10m or larger in space.

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Title: Could we identify hot Ocean-Planets with CoRoT, Kepler and Doppler velocimetry?
Authors: F. Selsis, B. Chazelas, P. Borde, M. Ollivier, F. Brachet, M. Decaudin, F. Bouchy, D. Ehrenreich, J.-M. Griessmeier, H. Lammer, C. Sotin, O. Grasset, C. Moutou, P. Barge, M. Deleuil, D. Mawet, D. Despois, J. F. Kasting, A. Leger
(Version v2)

Planets less massive than about 10 MEarth are expected to have no massive H-He atmosphere and a cometary composition (50% rocks, 50% water, by mass) provided they formed beyond the snowline of protoplanetary disks. Due to inward migration, such planets could be found at any distance between their formation site and the star. If migration stops within the habitable zone, this will produce a new kind of planets, called Ocean-Planets. Ocean-planets typically consist in a silicate core, surrounded by a thick ice mantle, itself covered by a 100 km deep ocean. The existence of ocean-planets raises important astrobiological questions: Can life originate on such body, in the absence of continent and ocean-silicate interfaces? What would be the nature of the atmosphere and the geochemical cycles ?
In this work, we address the fate of Hot Ocean-Planets produced when migration ends at a closer distance. In this case the liquid/gas interface can disappear, and the hot H2O envelope is made of a supercritical fluid. Although we do not expect these bodies to harbour life, their detection and identification as water-rich planets would give us insight as to the abundance of hot and, by extrapolation, cool Ocean-Planets.

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Planet hunters wanted to help astronomers in the search for new worlds
Astronomers at the University of California, Santa Cruz, are seeking the public's help to find and understand planets outside our solar system. But you don't need an advanced degree or even a telescope to participate--just a computer, access to the Internet, and an interest in astronomy.
The project, called Systemic, enlists volunteers to help astronomers better understand what kinds of planetary systems inhabit our galaxy, the Milky Way, and whether systems like our solar system are common. Astronomers have already found nearly 200 extrasolar planets orbiting other stars. But according to Gregory Laughlin, associate professor of astronomy and astrophysics at UCSC, the types of planetary systems astronomers are finding may not represent the full range of what is out there.

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Proving that the mysteries of space attract dollars as well as enthusiasts, astronomer Christopher Tinney has picked up a million-dollar grant to search for worlds beyond our solar system.

"It's very pleasing to be successful in such a tough competition" - Dr Christopher Tinney, Anglo Australian Observatory in Sydney.

Dr Tinney won a Discovery Project fellowship worth $1,201,305 over five years. His was one of nearly 5000 applications for federal funding through the Australian Research Council.

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