* Astronomy

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RE: Extrasolar Planets

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Title: Can Terrestrial Planets Form in Hot-Jupiter Systems?
Authors: Martyn J. Fogg, Richard P. Nelson

Models of terrestrial planet formation in the presence of a migrating giant planet have challenged the notion that hot-Jupiter systems lack terrestrial planets. We briefly review this issue and suggest that hot-Jupiter systems should be prime targets for future observational missions designed to detect Earth-sized and potentially habitable worlds.

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The discovery in recent years of a handful of rocky planets orbiting stars outside the Solar System has scientists wondering whether those planets are as suitable as Earth for life. This month, two research groups have entered the debate by butting heads over whether active plate tectonics are likely on such planets.
The movement of tectonic plates, which on our own planet created the Himalayas and moved the continents to their current positions, is thought to be important for moderating a planets temperature and recycling materials that may nourish life. But do 'super-Earths' planets with a mass up to ten times greater than our planet that are solid, unlike the gas giants have a similar geology to our home?

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Title: The Frequency of Large Radius Hot and Very Hot Jupiters in omega Centauri
Authors: David T F Weldrake (1), Penny D Sackett (2), Terry J Bridges (3). ((1) MPIA, Heidelberg, (2) RSAA, Mount Stromlo Observatory, (3) Queen's University)

We present the results of a deep, wide-field search for transiting `Hot Jupiter (HJ)' planets in the globular cluster omega Centauri. As a result of a 25-night observing run with the ANU 40-inch telescope at Siding Spring Observatory, a total of 109,726 stellar time series composed of 787 independent data points were produced with differential photometry in a 52x52' (0.75 deg² ) field centred on the cluster core, but extending well beyond. Taking into account the size of transit signals as a function of stellar radius, 45,406 stars have suitable photometric accuracy (<=0.045 mag to V=19.5) to search for transits. Of this sample, 31,000 stars are expected to be main sequence cluster members. All stars, both cluster and foreground, were subjected to a rigorous search for transit signatures; none were found. Extensive Monte Carlo simulations based on our actual data set allows us to determine the sensitivity of our survey to planets with radii ~1.5R_Jup, and thus place statistical upper limits on their occurrence frequency 'F'. Smaller planets are undetectable in our data. At 95% confidence, the frequency of Very Hot Jupiters (VHJs) with periods P satisfying 1d<P<3d can be no more than F_VHJ < 1/1040 in omega Cen. For HJ and VHJ distributed uniformly over the orbital period range 1d<P<5d, F_VHJ+HJ < 1/600. Our limits on large, short-period planets are comparable to those recently reported for other Galactic fields, despite being derived with less telescope time.

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Title: Planets Around Massive Subgiants
Authors: John A. Johnson

Compared to planets around Sun-like stars, relatively little is known about the occurrence rate and orbital properties of planets around stars more massive than 1.3 Msun. The apparent deficit of planets around massive stars is due to a strong selection bias against early-type dwarfs in Doppler-based planet searches. One method to circumvent the difficulties inherent to massive main-sequence stars is to instead observe them after they have evolved onto the subgiant branch. We show how the cooler atmospheres and slower rotation velocities of subgiants make them ideal proxies for F- and A-type stars. We present the early results from our planet search that reveal a paucity of planets orbiting within 1 AU of stars more massive than 1.5 Msun, and evidence of a rising trend in giant planet occurrence with stellar mass.

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Title: The Outer Cut-Off of the Giant Planet Population and the 6pc-Survey
Authors: D. Apai, M. R. Meyer, P. Hinz, M. Kasper

We present results from two high-contrast imaging surveys that exploit a novel technique, L-band angular differential imaging. Our first survey targeted 21 young stars in the Beta Pic and Tuc-Hor moving groups with VLT/NACO reaching typical sensitivities of <1 MJup at r > 20 AU. The statistical analysis of the null result demonstrates that the giant planet population is truncated at 30 AU or less (90% confidence level). Our second, on-going MMT/Clio survey utilises the unique sensitivity achieved in the L-band for old planets to probe all M-dwarf stars within 6 pc. The proximity of these targets enables direct imaging of planets in orbits like Jupiter for the first time - a key step for directly imaging giant planets.

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Title: HAT-P-6b: A Hot Jupiter transiting a bright F star
Authors: R. W. Noyes (1), G. A. Bakos (1,2), G. Torres (1), A. Pal (1,3), Geza Kovacs (4), D. W. Latham (1), J. M. Fernandez (1), D. A. Fischer (5), R. P. Butler (6), G. W. Marcy (7), B. Sipocz (3,1), G. A. Esquerdo (1), Gabor Kovacs (1), D. D. Sasselov (1), B. Sato (8), R. Stefanik (1), M. Holman (1), J. Lazar (9), I. Papp (9), P. Sari (9) ((1) CfA, 2: Hubble Fellow, (3) Department of Astronomy, Eötvös Loránd University, (4) Konkoly Observatory, (5) Department of Physics and Astronomy, San Francisco State University, (6) Department of Terrestrial Magnetism, Carnegie Institute of Washington, (7) Department of Astronomy, UC Berkeley, (8) Tokyo Institute of Technology, Tokyo, Japan, (9) Hungarian Astronomical Association)
(Version v2)

In the ongoing HATNet survey we have detected a giant planet, with radius 1.33 ± 0.06 RJup and mass 1.06 ± 0.12 MJup, transiting the bright (V = 10.5) star GSC 03239-00992. The planet is in a circular orbit with period 3.852985 ± 0.000005 days and mid-transit epoch 2,454,035.67575 +/- 0.00028 (HJD). The parent star is a late F star with mass 1.29 ± 0.06 Msun, radius 1.46 ± 0.06 Rsun, Teff ~ 6570 ± 80 K, [Fe=H] = -0.13 ± 0.08 and age ~ 2.3±^{0.5}_{0.7}Gy. With this radius and mass, HAT-P-6b has somewhat larger radius than theoretically expected. We describe the observations and their analysis to determine physical properties of the HAT-P-6 system, and briefly discuss some implications of this finding.

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Cha Ha 8

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RE: Extrasolar Planets

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Super Terre

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