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TOPIC: Extrasolar Planets
Blobrana


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RE: Extrasolar Planets
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IN ALL THE GALAXY, JUST 15 PERCENT OF SOLAR SYSTEMS ARE LIKE OURS

In their quest to find solar systems analogous to ours, astronomers have determined how common our solar system is.
They've concluded that about 15 percent of stars in the galaxy host systems of planets like our own, with several gas giant planets in the outer part of the solar system.

"Now we know our place in the universe. Solar systems like our own are not rare, but we're not in the majority, either" - Ohio State University astronomer Scott Gaudi.

Gaudi reported the results of the new study at the American Astronomical Society Meeting in Washington, DC

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Blobrana


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Kepler 4b, 5b, 6b, 7b and 8b
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NASA's Kepler space telescope, designed to find Earth-size planets in the habitable zone of sun-like stars, has discovered its first five new exoplanets, or planets beyond our solar system.
Kepler's high sensitivity to both small and large planets enabled the discovery of the exoplanets, named Kepler 4b, 5b, 6b, 7b and 8b. The discoveries were announced Monday, Jan. 4, by the members of the Kepler science team during a news briefing at the American Astronomical Society meeting in Washington.
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Blobrana


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Hidden Planets



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Blobrana


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Exeter astronomers discover 'tilted planets'

University of Exeter research has added to a growing evidence that several giant planets have orbits so tilted that their orbits can be perpendicular or even backwards relative to their parent star's rotation.
Known as 'extrasolar planets', because they are located outside our solar system, these Planets are formed from a swirling disk of gas and dust that surrounds young stars. Because the disk rotates in the same direction as the star, the planets spawned by the disk should revolve in the same direction. In an overcrowded planetary system, however, planets can push one body outward while flinging the other inward, elongating and tilting the inner planet's orbit.
The University of Exeter had already participated in the detection of two of these tilted planets in the past year, including the first know case, a planet known as "XO-3b".
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Blobrana


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Exoplanet atmospheres
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Title: Atmospheric Circulation of Exoplanets
Authors: Adam P. Showman, James Y-K. Cho, Kristen Menou

We survey the basic principles of atmospheric dynamics relevant to explaining existing and future observations of exoplanets, both gas giant and terrestrial. Given the paucity of data on exoplanet atmospheres, our approach is to emphasize fundamental principles and insights gained from Solar-System studies that are likely to be generalisable to exoplanets. We begin by presenting the hierarchy of basic equations used in atmospheric dynamics, including the Navier-Stokes, primitive, shallow-water, and two-dimensional nondivergent models. We then survey key concepts in atmospheric dynamics, including the importance of planetary rotation, the concept of balance, and scaling arguments to show how turbulent interactions generally produce large-scale east-west banding on rotating planets. We next turn to issues specific to giant planets, including their expected interior and atmospheric thermal structures, the implications for their wind patterns, and mechanisms to pump their east-west jets. Hot Jupiter atmospheric dynamics are given particular attention, as these close-in planets have been the subject of most of the concrete developments in the study of exoplanetary atmospheres. We then turn to the basic elements of circulation on terrestrial planets as inferred from Solar-System studies, including Hadley cells, jet streams, processes that govern the large-scale horizontal temperature contrasts, and climate, and we discuss how these insights may apply to terrestrial exoplanets. Although exoplanets surely possess a greater diversity of circulation regimes than seen on the planets in our Solar System, our guiding philosophy is that the multi-decade study of Solar-System planets reviewed here provides a foundation upon which our understanding of more exotic exoplanetary meteorology must build.

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Blobrana


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Extrasolar planets
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Title: Exoplanet Characterisation and the Search for Life
Authors: J. Kasting, W. Traub, A. Roberge, A. Leger, A. Schwartz, A. Wooten, A. Vosteen, A. Lo, A. Brack, A. Tanner, A. Coustenis, B. Lane, B. Oppenheimer, B. Mennesson, B. Lopez, C. Grillmair, C. Beichman, C. ****ell, C. Hanot, C. McCarthy, C. Stark, C. Marois, C. Aime, D. Angerhausen, D. Montes, D. Wilner, D. Defrere, D. Mourard, D. Lin, E. Kite, E. Chassefiere, F. Malbet, F. Tian, F. Westall, G. Illingworth, G. Vasisht, G. Serabyn, G. Marcy, G. Bryden, G. White, G. Laughlin, G. Torres, H. Hammel, H. Ferguson, H. Shibai, H. Rottgering, J. Surdej, J. Wiseman, J. Ge, J. Bally, J. Krist, J. Monnier, J. Trauger, J. Horner, J. Catanzarite, J. Harrington, J. Nishikawa, K. Stapelfeldt, K. von Braun, K. Biazzo, K. Carpenter, K. Balasubramanian, L. Kaltenegger, M. Postman, M. Spaans, M. Turnbull, M. Levine,
M. Burchell, M. Ealey, M. Kuchner, M. Marley, M. Dominik, M. Mountain, M. Kenworthy, M. Muterspaugh, M. Shao, M. Zhao, M. Tamura, N. Kasdin, N. Haghighipour, N. Kiang, N. Elias, N. Woolf, N. Mason, O. Absil, O. Guyon, O. Lay, P. Borde, P. Fouque, P. Kalas, P. Lowrance, P. Plavchan, P. Hinz, P. Kervella, P. Chen, R. Akeson, R. Soummer, R. Waters, R. Barry, R. Kendrick, R. Brown, R. Vanderbei, R. Woodruff, R. Danner, R. Allen, R. Polidan, S. Seager, S. MacPhee, S. Hosseini, S. Metchev, S. Kafka, S. Ridgway, S. Rinehart, S. Unwin, S. Shaklan, T. ten Brummelaar, T. Mazeh, V. Meadows, W. Weiss, W. Danchi, W. Ip, Y. Rabbia
et al. (55 additional authors not shown)

Over 300 extrasolar planets (exoplanets) have been detected orbiting nearby stars. We now hope to conduct a census of all planets around nearby stars and to characterize their atmospheres and surfaces with spectroscopy. Rocky planets within their star's habitable zones have the highest priority, as these have the potential to harbour life. Our science goal is to find and characterise all nearby exoplanets; this requires that we measure the mass, orbit, and spectroscopic signature of each one at visible and infrared wavelengths. The techniques for doing this are at hand today. Within the decade we could answer long-standing questions about the evolution and nature of other planetary systems, and we could search for clues as to whether life exists elsewhere in our galactic neighbourhood.

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Blobrana


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Astronomers may have found a way to identify those Sun-like stars most likely to harbour orbiting planets.
A survey of stars known to possess planets shows the vast majority to be severely depleted in lithium.
To date, scientists have detected just over 420 worlds circling other stars using a range of techniques.
Garik Israelian and colleagues tell the journal Nature that future planet hunts could be narrowed by going after stars with particular compositions.

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Lithium loss may be the planet-hunter's gain
Depletion of the element in stars might be linked to the existence of extrasolar planets.
The amount of lithium on the surface of a Sun-like star could be a telltale sign that it is orbited by extrasolar planets - a finding that could speed astronomers' attempts to detect them.

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Exoplanets Clue to Sun's Curious Chemistry
A ground-breaking census of 500 stars, 70 of which are known to host planets, has successfully linked the long-standing "lithium mystery" observed in the Sun to the presence of planetary systems. Using ESO's successful HARPS spectrograph, a team of astronomers has found that Sun-like stars that host planets have destroyed their lithium much more efficiently than "planet-free" stars. This finding does not only shed light on the lack of lithium in our star, but also provides astronomers with a very efficient way of finding stars with planetary systems.

"For almost 10 years we have tried to find out what distinguishes stars with planetary systems from their barren cousins. We have now found that the amount of lithium in Sun-like stars depends on whether or not they have planets" - Garik Israelian, lead author of a paper appearing this week in the journal Nature.

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Blobrana


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Planets 'spotted' outside our own galaxy for first time
Discoveries of exoplanets within the Milky Way have been happening regularly for some years now, with 403 found since the first one was spotted in 1995.
However, scientists studying remote galaxies, some up to 10 billion light years away, believe they have seen signs of planetary formation within them the first such evidence found.

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Ed ~ An Exoplanet had already been found in the Andromeda Galaxy (June 24 2009)

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