Context. There are numerous extrasolar giant planets which orbit close to their central stars. These ‘hot-Jupiters’ probably formed in the outer, cooler regions of their protoplanetary disks, and migrated inward to ∼ 0.1 AU. Since these giant planets must have migrated through their inner systems at an early time, it is uncertain whether they could have formed or retained terrestrial planets. A...

Atomic hydrogen escaping from the extrasolar giant planet HD209458b provides the largest observational signature ever detected for an extrasolar planet atmosphere. In fact, the upper atmosphere of this planet is evaporating. Observational evidences and interpretations coming from various models are reviewed. Implications for exoplanetology are discussed.

This paper continues an earlier study of giant planet migration, examining the effect of planet mass and disc viscosity on the migration rate. We find that the migration rate of a gap-opening planet varies systematically with the planet’s mass, as predicted in our earlier work. However, the variation with disc viscosity appears to be much weaker than expected.

We present a catalog of 11 multi-planet systems from Campaigns 1 and 2 of the K2 mission. We report the sizes and orbits of 26 planets split between seven 2-planet systems and four 3-planet systems. These planets stem from a systematic search of the K2 photometry for all dwarf stars observed by K2 in these fields. We precisely characterized the host stars with adaptive optics imaging and analys...

To move one step forward toward a Galactic distribution of planets, we present the first planet sensitivity analysis for microlensing events with simultaneous observations from space and the ground. We present this analysis for two such events, OGLE-2014-BLG-0939 and OGLE-2014-BLG-0124, which both show substantial planet sensitivity even though neither of them reached high magnification. This s...

Close-in giant planets (e.g., "hot Jupiters") are thought to form far from their host stars and migrate inward, through the terrestrial planet zone, via torques with a massive gaseous disk. Here we simulate terrestrial planet growth during and after giant planet migration. Several-Earth-mass planets also form interior to the migrating jovian planet, analogous to recently discovered "hot Earths....

In this letter we present the discovery of a very light planetary companion to the star μAra (HD 160691). The planet orbits its host once every 9.5 days, and induces a sinusoidal radial velocity signal with a semi-amplitude of 4.1 m s, the smallest Doppler amplitude detected so far. These values imply a mass of m2 sin i=14 M⊕ (earth-masses). This detection represents the discovery of a planet w...

In this letter we report the possible existence of a second planet in the transiting extrasolar planet system HD 17156 and its interactive dynamics with the previously known planet. The analysis is achieved through the pofp optimization software which is based on a full integration of the system’s multiple-body Newtonian equations of motion. The two-planet solution yields a significantly improv...

We present Spitzer 8 μm transit observations of the extrasolar planet HD 149026b. At this wavelength, transit light curves are weakly affected by stellar limb-darkening, allowing for a simpler and more accurate determination of planetary parameters. We measure a planet-star radius ratio of Rp/R⋆ = 0.05158± 0.00077, and in combination with ground-based data and independent constraints on the ste...

In this letter we report the possible existence of a second planet in the transiting extrasolar planet system HD17156 and its interactive dynamics with the previously known planet. The analysis is achieved through the POFP optimization software which is based on a full integration of the system’s multiple-body Newtonian equations of motion. The two-planet solution yields a significantly improve...