Showing papers by "François Bouchy published in 2015"
TL;DR: In this paper, the second multiplanetary system discovered with K2 observations, K2-19-19b, was used to detect the chopping signal of the dynamic interaction of the planets that in turn permits to uniquely characterize the system.
Abstract: K2-19 is the second multiplanetary system discovered with K2 observations. The system is composed of two Neptune size planets close to the 3: 2 mean-motion resonance. To better characterize the system we obtained two additional transit observations of K2-19b and five additional radial velocity observations. These were combined with K2 data and fitted simultaneously with the system dynamics ( photodynamical model) which increases the precision of the transit time measurements. The higher transit time precision allows us to detect the chopping signal of the dynamic interaction of the planets that in turn permits to uniquely characterize the system. Although the reflex motion of the star was not detected, dynamic modelling of the system allowed us to derive planetary masses of M-b = 44 +/- 12 M-circle plus and M-c = 15.9 +/- 7.0 M-circle plus for the inner and the outer planets, respectively, leading to densities close to Uranus. We also show that our method allows the derivation of mass ratios using only the 80 d of observations during the first campaign of K2.
72 citations
TL;DR: In this article, a two-planet system of Neptune sized objects (4.2 and 7.2 $R_\oplus$), orbiting a K dwarf extremely close to the 3:2 mean motion resonance was discovered.
Abstract: The K2 mission has recently begun to discover new and diverse planetary systems. In December 2014 Campaign 1 data from the mission was released, providing high-precision photometry for ~22000 objects over an 80 day timespan. We searched these data with the aim of detecting further important new objects. Our search through two separate pipelines led to the independent discovery of K2-19b \& c, a two-planet system of Neptune sized objects (4.2 and 7.2 $R_\oplus$), orbiting a K dwarf extremely close to the 3:2 mean motion resonance. The two planets each show transits, sometimes simultaneously due to their proximity to resonance and alignment of conjunctions. We obtain further ground based photometry of the larger planet with the NITES telescope, demonstrating the presence of large transit timing variations (TTVs), and use the observed TTVs to place mass constraints on the transiting objects under the hypothesis that the objects are near but not in resonance. We then statistically validate the planets through the \texttt{PASTIS} tool, independently of the TTV analysis.
66 citations
TL;DR: In this paper, a warm Neptune with a minimum mass of 16.1 +- 2.7 Mearth was detected orbiting the solar analog HD164595 in 40 +- 0.24 days.
Abstract: High-precision radial velocity surveys explore the population of low-mass exoplanets orbiting bright stars. This allows accurately deriving their orbital parameters such as their occurrence rate and the statistical distribution of their properties. Based on this, models of planetary formation and evolution can be constrained. The SOPHIE spectrograph has been continuously improved in past years, and thanks to an appropriate correction of systematic instrumental drift, it is now reaching 2 m/s precision in radial velocity measurements on all timescales. As part of a dedicated radial velocity survey devoted to search for low-mass planets around a sample of 190 bright solar-type stars in the northern hemisphere, we report the detection of a warm Neptune with a minimum mass of 16.1 +- 2.7 Mearth orbiting the solar analog HD164595 in 40 +- 0.24 days . We also revised the parameters of the multiplanetary system around HD190360. We discuss this new detection in the context of the upcoming space mission CHEOPS, which is devoted to a transit search of bright stars harboring known exoplanets.
56 citations
TL;DR: In this paper, the authors describe radial-velocity time series obtained by HARPS on the 3.60 m telescope in La Silla (ESO, Chile) over ten years and report the discovery of five new giant exoplanets in distant orbits; these new planets orbit the stars HD 564, HD 30669, HD 108341, and BD -114672.
Abstract: We describe radial-velocity time series obtained by HARPS on the 3.60 m telescope in La Silla (ESO, Chile) over ten years and report the discovery of five new giant exoplanets in distant orbits; these new planets orbit the stars HD 564, HD 30669, HD 108341, and BD -114672. Their periods range from 492 to 1684 days, semi-major axes range from 1.2 to 2.69 AU, and eccentricities range from 0 to 0.85. Their minimum mass ranges from 0.33 to 3.5 M-Jup. We also refine the parameters of two planets announced previously around HD 113538, based on a longer series of measurements. The planets have a period of 663 +/- 8 and 1818 +/- 25 days, orbital eccentricities of 0.14 +/- 0.08 and 0.20 +/- 0.04, and minimum masses of 0.36 +/- 0.04 and 0.93 +/- 0.06 M-Jup. Finally, we report the discovery of a new hot-Jupiter planet around an active star, HD 103720; the planet has a period of 4.5557 +/- 0.0001 days and a minimum mass of 0.62 +/- 0.025 M-Jup. We discuss the fundamental parameters of these systems and limitations due to stellar activity in quiet stars with typical 2 ms(-1) radial velocity precision.
37 citations
TL;DR: In this paper, the authors reported the discovery of a new transiting planet from the WASP survey, named WASP-135b, which is a hot Jupiter with a radius of 1.30 pm 0.09 Rjup and an orbital period of 2.401 days.
Abstract: We report the discovery of a new transiting planet from the WASP survey. WASP-135b is a hot Jupiter with a radius of 1.30 pm 0.09 Rjup, a mass of 1.90 pm 0.08 Mjup and an orbital period of 1.401 days. Its host is a Sun-like star, with a G5 spectral type and a mass and radius of 0.98 pm 0.06 Msun and 0.96 pm 0.05 Rsun respectively. The proximity of the planet to its host means that WASP-135b receives high levels of insolation, which may be the cause of its inflated radius. Additionally, we find weak evidence of a transfer of angular momentum from the planet to its star.
18 citations
01 Sep 2015
TL;DR: In this paper, the authors present the analysis of the multi-planetary system Kepler-117, which is composed of a ~ 30 M Earth planet in a ~ 19 days orbit and a ~ 2 M J planet orbiting in ~ 51 days.
Abstract: 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 M Earth planet in a ~ 19 days orbit and a ~ 2 M J 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.
5 citations
01 Aug 2015
TL;DR: In this paper, a photo-dynamical model is used to constrain the masses of near-resonant systems even when the full libration curve is not observed.
Abstract: In traditional transit timing variations (TTVs) analysis of multi-planetary systems, the individual TTVs are first derived from transit fitting and later modelled using n-body dynamic simulations to constrain planetary masses We show that fitting simultaneously the transit light curves with the system dynamics (photo-dynamical model) increases the precision of the TTV measurements and helps constrain the system architecture We exemplify the advantages of applying this photo-dynamical model to a multi-planetary system found in K2 data very close to 3:2 mean motion resonance, K2-19 In this case the period of the larger TTV variations (libration period) is much longer (>15 years) than the duration of the K2 observations (80 days) However, our method allows to detect the short period TTVs produced by the orbital conjunctions between the planets that in turn permits to uniquely characterise the system Therefore, our method can be used to constrain the masses of near-resonant systems even when the full libration curve is not observed
1 citations
01 Oct 2015
TL;DR: In this article, a common noise model was used to obtain consistent results on the planetary transmission spectrum of WASP-49b for all three dates of three separate transit observations, and it was shown that this planet possesses hazes or clouds.
Abstract: Transmission spectra obtained via multi-wavelength observations of transits are one of the most prominent pathways for the study of exoplanet atmospheres. We present results obtained with the ESO/VLT FORS2 instrument on the hot Saturn-mass exoplanet WASP-49b, based on three separate transit observations. FORS2 is known to produce substantial correlated noise due to inhomogeneous transparency of the telescope’s linear atmospheric dispersion corrector. We account for theses systematics in a common way by using a common noise model approach. By using this approach together with low-order functions compensating for chromatic slopes, we obtain consistent results on the planetary transmission spectrum for all three dates. We do not identify any absorption signatures in the atmosphere of WASP-49b and thus conclude that this planet possesses hazes or clouds.
01 Oct 2015
TL;DR: In this paper, the SOPHIE Exoplanets Consortium used the spectrograph at the 1.93m telescope of the Haute-Provence Observatory to perform radial velocity and activity measurements.
Abstract: We present radial velocity and activity measurements obtained in subprograms conducted by the SOPHIE Exoplanets Consortium, using the SOPHIE spectrograph at the 1.93-m telescope of the Haute-Provence Observatory. We selected targets previously observed with ELODIE, the predecessor of SOPHIE, showing clear trends in radial velocity. This unique sample allows to extend the time base over 20 years to find substellar companions beyond 5 AU. As part of this subprogram, we report the detection of Jupiter-analogs and new brown-dwarf companions and discuss their properties. Such companions are prime targets for high-angular resolution direct imaging and astrometry. We also discuss diagnostics to disentangle long-term radial velocity trend with stellar magnetic cycles. To do so, we use the H-alpha line, present in both ELODIE and SOPHIE spectra, and the Ca II H & K lines only exploitable in the SOPHIE data. Additionally, we show preliminary results of the SOPHIE follow-up of known transiting hot Jupiters from different photometric surveys. These results include a system with a possible longperiod companion.