* Astronomy

 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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"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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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: 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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