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Title: Characterisation of the four new transiting planets KOI-188b, KOI-195b, KOI-192b, and KOI-830b
Author: G. Hebrard, A. Santerne, G. Montagnier, G. Bruno, M. Deleuil, M. Havel, J.-M. Almenara, C. Damiani, S.C.C. Barros, A.S. Bonomo, F. Bouchy, R.F. Diaz, C. Moutou

The characterisation of four new transiting extrasolar planets is presented here. KOI-188b and KOI-195b are bloated hot Saturns, with orbital periods of 3.8 and 3.2 days, and masses of 0.25 and 0.34 M_Jup, respectively. They are located in the low-mass range of known transiting, giant planets. KOI-192b has a similar mass (0.29 M_Jup) but a longer orbital period of 10.3 days. This places it in a domain where only few planets are known. KOI-830b, finally, with a mass of 1.27 M_Jup and a period of 3.5 days, is a typical hot Jupiter. The four planets have radii of 0.98, 1.09, 1.2, and 1.08 R_Jup, respectively. We detected no significant eccentricity in any of the systems, while the accuracy of our data does not rule out possible moderate eccentricities. The four objects were first identified by the Kepler Team as promising candidates from photometry of the Kepler satellite. We establish here their planetary nature thanks to the radial velocity follow-up we secured with the HARPS-N spectrograph at the Telescopio Nazionale Galileo. The combined analyses of the whole datasets allow us to fully characterise the four planetary systems. These new objects increase the number of well-characterised exoplanets for statistics, and provide new targets for individual follow-up studies. The pre-screening we performed with the SOPHIE spectrograph at the Observatoire de Haute-Provence as part of that study also allowed us to conclude that a fifth candidate, KOI-219.01, is not a planet but is a false positive.

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 Hubble Finds Three Surprisingly Dry Exoplanets

Astronomers using NASA's Hubble Space Telescope have gone looking for water vapour in the atmospheres of three planets orbiting stars similar to the Sun - and have come up nearly dry.
The three planets, HD 189733b, HD 209458b, and WASP-12b, are between 60 and 900 light-years away. These giant gaseous worlds are so hot, with temperatures between 1,500 and 4,000 degrees Fahrenheit, that they are ideal candidates for detecting water vapour in their atmospheres.
However, to the surprise of the researchers, the planets surveyed have only one-tenth to one one-thousandth the amount of water predicted by standard planet-formation theories.

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Title: Most 1.6 Earth-Radius Planets are not Rocky
Author: Leslie A. Rogers

The Kepler Mission, combined with ground based radial velocity follow-up and dynamical analyses of transit timing variations, has revolutionized the observational constraints on sub-Neptune-size planet compositions. The results of an extensive Kepler follow-up program including multiple Doppler measurements for 22 planet-hosting stars (Marcy et al. 2014) more than doubles the population of sub-Neptune-sized transiting planets that have radial velocity mass constraints. This unprecedentedly large and homogeneous sample of planets with both mass and radius constraints opens the possibility of a statistical study of the underlying population of planet compositions. We focus on the intriguing transition between rocky exoplanets (comprised of iron and silicates) and planets with voluminous layers of volatiles (H/He and astrophysical ices). Applying a hierarchical bayesian statistical approach to the sample of Kepler transiting sub-Neptune planets with Keck radial velocity follow-up, we constrain the fraction of close-in planets (with orbital periods less than ~50 days) that are sufficiently dense to be rocky, as a function of planet radius. We show that the majority of 1.6 Earth-radius planets are too low density to be comprised of Fe and silicates alone. At larger radii, the constraints on the fraction of rocky planets are even more stringent. These insights into the size demographics of rocky and volatile-rich planets offer empirical constraints to planet formation theories, and guide the range of planet radii to be considered in studies of the occurrence rate of "Earth-like" planets, Earth.

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"Neapolitan" Exoplanets Come in Three Flavours

The planets of our solar system come in two basic flavours, like vanilla and chocolate ice cream. We have small, rocky terrestrials like Earth and Mars, and large gas giants like Neptune and Jupiter. We're missing the astronomical equivalent of strawberry ice cream - planets between about one and four times the size of Earth. NASA's Kepler mission has discovered that these types of planets are very common around other stars.
New research following up on the Kepler discoveries shows that alien worlds, or exoplanets, can be divided into three groups - terrestrials, gas giants, and mid-sized "gas dwarfs" - based on how their host stars tend to fall into three distinct groups defined by their compositions.

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NASA's Kepler Mission Announces a Planet Bonanza, 715 New Worlds

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Title: Lightcurves of Stars & Exoplanets: Estimating Inclination, Obliquity, and Albedo
Authors: Nicolas B. Cowan (Northwestern University), Pablo A. Fuentes (University of Chile), Hal M. Haggard (Centre de Physique Theorique de Luminy)

It is possible to determine a star or planet's brightness markings by analysing its disk-integrated brightness variations, in either thermal or reflected light. We compute the "harmonic lightcurves" resulting from spherical harmonic maps of intensity or albedo. These convolutions often contain a nullspace: a class of non-zero maps that have no lightcurve signature. We derive harmonic thermal lightcurves for both equatorial and inclined observers. The nullspace for these two viewing geometries is significantly different, with odd modes being present in the latter case, but not the former. We therefore suggest that the Fourier spectrum of a thermal lightcurve is sufficient to determine the orbital inclination of non-transiting short-period planets, the rotational inclination of stars and brown dwarfs, and the obliquity of directly imaged planets. In the best-case scenario of a nearly edge-on rotator, factor-of-two measurements of the amplitudes of odd modes in the thermal lightcurve provide an inclination estimate good to a few degrees. In general, however, inclination estimates will remain qualitative until detailed hydrodynamic simulations and/or occultation maps can be used as a calibrator. We further derive harmonic reflected lightcurves for tidally-locked planets; these are higher-order versions of the well-known Lambert phase curve. We show that a non-uniform diffusely-reflecting planet with a precisely Lambertian phase curve may have planetary and Bond albedos significantly different from that inferred if the planet is assumed to be uniform. Lastly, we provide low-order analytic expressions for harmonic lightcurves that can be used for fitting observed photometry; as a general rule, edge-on solutions cannot simply be scaled by sin(i) to mimic inclined lightcurves.

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Title: Why Does Nature Form Exoplanets Easily?
Authors: Kevin Heng

The ubiquity of worlds beyond our Solar System confounds us.

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Title: Planetary Companions to Three Evolved Intermediate-Mass Stars: HD 2952, HD 120084, and o Serpentis
Authors: Bun'ei Sato, Masashi Omiya, Hiroki Harakawa, Yu-Juan Liu, Hideyuki Izumiura, Eiji Kambe, Yoichi Takeda, Michitoshi Yoshida, Yoichi Itoh, Hiroyasu Ando, Eiichiro Kokubo, Shigeru Ida

We report the detections of planetary companions orbiting around three evolved intermediate-mass stars from precise radial velocity measurements at Okayama Astrophysical Observatory. HD 2952 (K0III, 2.5 solar masses) and o Ser (G8III, 2.2 solar masses) host a relatively low mass planet with minimum mass of m_2sin i=1.6 Jupiter masses and 1.7 Jupiter masses in nearly circular orbits with period of P=312 and 277 d, respectively. HD 120084 (G7 III, 2.4 solar masses) hosts an eccentric planet with m_2sin i=4.5 Jupiter masses in an orbit with P=2082 d and eccentricity of e=0.66. The planet has one of the largest eccentricities among those ever discovered around evolved intermediate-mass stars, almost all of which have eccentricity smaller than 0.4. We also show that radial velocity variations of stellar oscillations for G giants can be averaged out below a level of a few m/s at least in timescale of a week by high cadence observations, which enables us to detect a super-Earth and a Neptune-mass planet in short-period orbits even around such giant stars.

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NASA's Kepler Discovers 461 New Planet Candidates

NASA's Kepler mission Monday announced the discovery of 461 new planet candidates. Four of the potential new planets are less than twice the size of Earth and orbit in their sun's "habitable zone," the region in the planetary system where liquid water might exist on the surface of a planet.
Based on observations conducted from May 2009 to March 2011, the findings show a steady increase in the number of smaller-size planet candidates and the number of stars with more than one candidate.

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Title: Investigating Nearby Exoplanets via Interstellar Radar
Authors: Louis K. Scheffer

Interstellar radar is a potential intermediate step between passive observation of exoplanets and interstellar exploratory missions. Compared to passive observation, it has the traditional advantages of radar astronomy. It can measure surface characteristics, determine spin rates and axes, provide extremely accurate ranges, construct maps of planets, distinguish liquid from solid surfaces, find rings and moons, and penetrate clouds. It can do this even for planets close to the parent star. Compared to interstellar travel or probes, it also offers significant advantages. The technology required to build such a radar already exists, radar can return results within a human lifetime, and a single facility can investigate thousands of planetary systems. The cost, although high, is within the reach of Earth's economy, so it is cheaper as well.

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