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We present the analysis of the multi-planetary system Kepler-117, which is part of our program of observations of Kepler planets. This system is composed of a ~ 30 MEarth planet in a ~ 19 days orbit and a ~ 2 MJ planet orbiting in ~ 51 days. Both the orbits have low eccentricity. The planets are not close to an exact low-order mean motion resonance, but exhibit significant transit timing variations (TTVs) nevertheless. We perform a combined Markov Chain Monte Carlo fit on all the available data: the Kepler photometry, the TTVs, the radial velocities we obtained with SOPHIE/OHP and the stellar parameters. The prime result is that the modelling of the TTVs allows to increase the precision on the system parameters which are not constrained by the radial velocities alone.

CoRoT-11b is a fairly massive hot-Jupiter (Mp = 2.33 ± 0.34 MJup ) in a 3 days orbit around a F6 V star with an age of 2 ± 1 Gyr. The relatively high projected rotational velocity of the star (v sin i⋆ = 40 ± 5 km/s) places CoRoT-11 among the most rapidly rotating planet hosting stars discovered so far. Assuming that the star is seen equator-on, the v sin i⋆ and the star radius (R∗ = 1.37±0.03 R⊙) translate into a stellar rotation period of 1.73±0.26 days. This peculiar planet/star configuration offers an unique opportunity to study the tidal evolution of the system. Owing to the strong tidal interaction, the planet would have moved outwards, from a starting semi-major axis corresponding to an orbital period almost synchronized with the stellar rotation. We found that the present value of the tidal quality factor Q′s could be measured by a timing of the mid-epoch of the transits to be observed with an accuracy of about 0.5 − 1 seconds over a time baseline of about 25 years.

We report the validation and characterization of three new transiting exoplanets using SOPHIE radial velocities: KOI-614b, KOI-206b, and KOI-680b. KOI-614b has a mass of 2.86 ± 0.35 MJup and a radius of 1.13+0.26-0.18 RJup, and it orbits a G0, metallic ([ Fe/H ] = 0.35 ± 0.15) dwarf in 12.9 days. Its mass and radius are familiar and compatible with standard planetary evolution models, so it is one of the few known transiting planets in this mass range to have an orbital period over ten days. With an equilibrium temperature of Teq = 1000 ± 45 K, this places KOI-614b at the transition between what is usually referred to as "hot" and "warm" Jupiters. KOI-206b has a mass of 2.82 ± 0.52 MJup and a radius of 1.45 ± 0.16 RJup, and it orbits a slightly evolved F7-type star in a 5.3-day orbit. It is a massive inflated hot Jupiter that is particularly challenging for planetary models because it requires unusually large amounts of additional dissipated energy in the planet. On the other hand, KOI-680b has a much lower mass of 0.84 ± 0.15 MJup and requires less extra-dissipation to explain its uncommonly large radius of 1.99 ± 0.18 RJup. It is one of the biggest transiting planets characterized so far, and it orbits a subgiant F9-star well on its way to the red giant stage, with an orbital period of 8.6 days. With host stars of masses of 1.46 ± 0.17 M⊙ and 1.54 ± 0.09 M⊙, respectively, KOI-206b, and KOI-680b are interesting objects for theories of formation and survival of short-period planets around stars more massive than the Sun. For those two targets, we also find signs of a possible distant additional companion in the system. [ABSTRACT FROM AUTHOR]

As part of our follow-up campaign of Kepler planets, we observed Kepler-117 with the SOPHIE spectrograph at the Observatoire de Haute-Provence. This F8-type star hosts two transiting planets in non-resonant orbits. The planets, Kepler-117 b and c, have orbital periods ≃ 18.8 and ≃ 50.8 days, and show transit-timing variations (TTVs) of several minutes. We performed a combined Markov chain Monte Carlo (MCMC) fit on transits, radial velocities, and stellar parameters to constrain the characteristics of the system. We included the fit of the TTVs in the MCMC by modeling them with dynamical simulations. In this way, consistent posterior distributions were drawn for the system parameters. According to our analysis, planets b and c have notably different masses (0.094 ± 0.033 and 1.84 ± 0.18MJ) and low orbital eccentricities (0.0493 ± 0.0062 and 0.0323 ± 0.0033). The uncertainties on the derived parameters are strongly reduced if the fit of the TTVs is included in the combined MCMC. The TTVs allow measuring the mass of planet b although its radial velocity amplitude is poorly constrained. Finally, we checked that the best solution is dynamically stable. [ABSTRACT FROM AUTHOR]

We present the radial-velocity follow-up of two Kepler planetary transiting candidates (KOI-189 and KOI-686) carried out with the SOPHIE spectrograph at the Observatoire de Haute Provence. These data promptly discard these objects as viable planet candidates and show that the transiting objects are in the regime of very low-mass stars, where a strong discrepancy between observations and models persists for the mass and radius parameters. By combining the SOPHIE spectra with the Kepler light curve and photometric measurements found in the literature, we obtain a full characterization of the transiting companions, their orbits, and their host stars. The two companions are in significantly eccentric orbits with relatively long periods (30 days and 52.5 days), which makes them suitable objects for a comparison with theoretical models, since the effects invoked to understand the discrepancy with observations are weaker for these orbital distances. KOI-189 b has a mass M = 0:0745 ±0:0033 M☉ and a radius R = 0:1025 ± 0:0024 R☉. The density of KOI-189 b is significantly lower than expected from theoretical models for a system of its age. We explore possible explanations for this difference. KOI-189 b is the smallest hydrogen-burning star with such a precise determination of its fundamental parameters. KOI-686 b is larger and more massive (M = 0:0915 ±0:0043 M☉; R = 0:1201 ±0:0033 R☉), and its position in the mass-radius diagram agrees well with theoretical expectations. [ABSTRACT FROM AUTHOR]

Context. Hot Jupiters are still a fascinating exoplanet population that presents a diversity we are still far from understanding. High-precision photometric observations combined with radial velocity measurements give us a unique opportunity to constrain their properties better, on both their internal structure and their atmospheric bulk properties. Aims. We initiated a follow-up program of Kepler-released planet candidates with the goal of confirming the planetary nature of a number of them through radial velocity measurements. For those that successfully passed the radial velocity screening, we furthermore performed a detailed exploration of their properties to characterize the systems. As a byproduct, these systematic observations allow us to consolidate the exoplanets' occurrence rate. Methods. We performed a complete analysis of the Kepler-412 system, listed as planet candidate KOI-202 in the Kepler catalog, by combining the Kepler observations from Q1 to Q15, to ground-based spectroscopic observations that allowed us to derive radial velocity measurements, together with the host-star parameters and properties. We also analyzed the light curve to derive the star's rotation period and the phase function of the planet, including the secondary eclipse. Results. We secured the planetary nature of Kepler-412b. We found the planet has a mass of 0.939 ± 0.085 MJup and a radius of 1.325 ± 0.043 RJup, which makes it a member of the bloated giant subgroup. It orbits its G3 V host star in 1.72 days. The system has an isochronal age of 5.1 Gyr, consistent with its moderate stellar activity as observed in the Kepler light curve and the rotation of the star of 17.2 ± 1.6 days. From the detected secondary we derived the day-side temperature as a function of the geometric albedo. We estimated that the geometrical albedo Ag should be between 0.094 ± 0.015 and 0.013 +0.017 -0.013 and the brightness of the day side 2380± 40 K. The measured night-side flux corresponds to a night-side brightness temperature of 2154± 83 K, much greater than what is expected for a planet with homogeneous heat redistribution. From the comparison to star and planet evolution models, we found that dissipation should operate in the deep interior of the planet. This modeling also shows that despite its inflated radius, the planet presents a noticeable amount of heavy elements, which accounts for a mass fraction of 0.11 ± 0.04. [ABSTRACT FROM AUTHOR]

The exoplanet KOI-142b (Kepler-88b) shows transit timing variations (TTVs) with a semi-amplitude of ~12 h, which earned it the nickname "king of transit variations". Only the transit of planet b was detected in the Kepler data with an orbital period of ~10.92 days and a radius of ~0.36 RJup. The TTVs together with the transit duration variations of KOI-142b were analysed recently, finding a unique solution for a companion-perturbing planet. An outer non-transiting companion was predicted, KOI-142c, with a mass of 0.626 ± 0.03 MJup and a period of 22.3397-0.0018+0.0021 days, which is close to the 2:1 mean-motion resonance with the inner transiting planet. We report an independent confirmation of KOI-142c using radial velocity observations with the SOPHIE spectrograph at the Observatoire de Haute-Provence. We derive an orbital period of 22.10 ± 0.25 days and a minimum planetary mass of 0.760.16+0.32 MJup, both in good agreement with the predictions by previous transit timing analysis. Therefore, this is the first radial velocity confirmation of a non-transiting planet discovered with TTVs, providing an independent validation of the TTVs technique. [ABSTRACT FROM AUTHOR]

We report the discovery of a transiting brown dwarf companion to KOI-205, a K0 main-sequence star, in a 11.720125-day period orbit. The transits were detected by the Kepler space telescope, and the reflex motion of the star was measured using radial velocity observations obtained with the SOPHIE spectrograph. The atmospheric parameters of the host stars were determined from the analysis of high-resolution, high signal-to-noise ratio ESPaDOns spectra obtained for this purpose. Together with spectrophotometric measurements recovered from the literature, these spectra indicate that the star is a mildly metallic K0 dwarf with Teff 5237 ± 60 K. The mass of the companion is 39:9±1:0 MJup and its radius is 0:81±0:02 RJup, in agreement with current theoretical predictions. This is the first time a bona fide brown dwarf companion is detected in orbit around a star of this type. The formation and orbital evolution of brown dwarf companions is briefly discussed in the light of this new discovery. [ABSTRACT FROM AUTHOR]

We report the discovery of a new stellar companion in the KOI-13 system. KOI-13 is composed of two fast-rotating A-type stars of similar magnitude. One of these two stars hosts a transiting planet discovered by Kepler. We obtained new radial velocity measurements using the SOPHIE spectrograph at the Observatoire de Haute-Provence that reveal an additional companion in this system. This companion has a mass of between 0.4 M⊙ and 1 M⊙ and orbits one of the two main stars with a period of 65.831 ± 0.029 days and an eccentricity of 0.52 ± 0.02. The radial velocities of the two stars are derived using a model of two fast-rotating line profiles. From the residuals, we find a hint of the stellar variations seen in the Kepler light curve, which have an amplitude of about 1.41 km s-1 and a period close to the rotational period. This signal appears to be about three orders of magnitude larger than expected for stellar activity. From the analysis of the residuals, we also put a 3-σ upper limit on the mass of the transiting planet KOI-13.01 of 14.8 MJup and 9.4 MJup, depending on which star hosts the transit. We find that this new companion has no significant impact on the photometric determination of the mass of KOI-13.01 but is expected to affect precise infrared photometry. Finally, using dynamical simulations, we infer that the new companion is orbiting around KOI-13B and that the transiting planet candidate is expected to orbit KOI-13A. Thus, the transiting planet candidate KOI-13.01 is orbiting the main component of a hierarchical triple system. [ABSTRACT FROM AUTHOR]