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This paper presents near-infrared spectropolarimetric and velocimetric observations of the young planet-hosting T Tauri star PDS 70, collected with SPIRou at the 3.6-m Canada–France–Hawaii Telescope from 2020 to 2024. Clear Zeeman signatures from magnetic fields at the surface of PDS 70 are detected in our data set of 40 circularly polarized spectra. Longitudinal fields inferred from Zeeman signatures, ranging from |$-116$| to 176 G, are modulated on a time-scale of |$3.008\pm 0.006$| d, confirming that this is the rotation period of PDS 70. Applying Zeeman–Doppler imaging to subsets of unpolarized and circularly polarized line profiles, we show that PDS 70 hosts low-contrast brightness spots and a large-scale magnetic field in its photosphere, featuring in particular a dipole component of strength 200–420 G that evolves on a time-scale of months. From the broadening of spectral lines, we also infer that PDS 70 hosts a small-scale field of |$2.51\pm 0.12$| kG. Radial velocities derived from unpolarized line profiles are rotationally modulated as well, and exhibit additional longer term chromatic variability, most likely attributable to magnetic activity rather than to a close-in giant planet (with a 3 |$\sigma$| upper limit on its minimum mass of |$\simeq$| 4 at a distance of |$\simeq$| 0.2 au). We finally confirm that accretion occurs at the surface of PDS 70, generating modulated redshifted absorption in the 1083.3-nm He  i triplet, and show that the large-scale magnetic field, often strong enough to disrupt the inner accretion disc up to the corotation radius, weakens as the star gets fainter and redder (as in 2022), suggesting that dust from the disc more easily penetrates the stellar magnetosphere in such phases. [ABSTRACT FROM AUTHOR]

In this paper, we report near-infrared observations of the classical T Tauri star TW Hya with the SPIRou high-resolution spectropolarimeter and velocimeter at the 3.6-m Canada–France–Hawaii Telescope in 2019, 2020, 2021, and 2022. By applying Least-Squares Deconvolution (LSD) to our circularly polarized spectra, we derived longitudinal fields that vary from year to year from –200 to +100 G, and exhibit low-level modulation on the 3.6 d rotation period of TW Hya, despite the star being viewed almost pole-on. We then used Zeeman–Doppler Imaging to invert our sets of unpolarized and circularly polarized LSD profiles into brightness and magnetic maps of TW Hya in all four seasons, and obtain that the large-scale field of this T Tauri star mainly consists of a 1.0–1.2 kG dipole tilted at about 20° to the rotation axis, whereas the small-scale field reaches strengths of up to 3–4 kG. We find that the large-scale field is strong enough to allow TW Hya to accrete material from the disc on the polar regions at the stellar surface in a more or less geometrically stable accretion pattern, but not to succeed in spinning down the star. We also report the discovery of a radial velocity signal of semi-amplitude |$11.1^{+3.3}_{-2.6}$| m s−1 (detected at 4.3σ) at a period of 8.3 d in the spectrum of TW Hya, whose origin may be attributed to either a non-axisymmetric density structure in the inner accretion disc, or to a |$0.55^{+0.17}_{-0.13}$| MꝜ candidate close-in planet (if orbiting in the disc plane), at an orbital distance of 0.075 ± 0.001 au. [ABSTRACT FROM AUTHOR]

We report new observations of the classical T Tauri star CI Tau with the SPIRou near-infrared spectropolarimeter and velocimeter at the Canada–France–Hawaii Telescope (CFHT) in late 2019, 2020, and 2022, complemented with observations obtained with the ESPaDOnS optical spectropolarimeter at CFHT in late 2020. From our SPIRou and ESPaDOnS spectra, to which we applied least-squares deconvolution, we infer longitudinal fields clearly modulated with the 9-d rotation period of CI Tau. Using Zeeman–Doppler imaging, we reconstruct the large-scale magnetic topology, first from SPIRou data only in all three seasons, then from our 2020 SPIRou and ESPaDOnS data simultaneously. We find that CI Tau hosts a mainly axisymmetric poloidal field, with a 1 kG dipole slightly tilted to the rotation axis and dark spots close to the pole that coincide with the footpoints of accretion funnels linking the star to the inner disc. Our results also suggest that CI Tau accretes mass from the disc in a stable fashion. We further find that radial velocities (RVs) derived from atomic and CO lines in SPIRou spectra are both rotationally modulated, but with a much lower amplitude than that expected from the putative candidate planet CI Tau b. We confirm the presence of a RV signal at a period of 23.86 d reported in a separate analysis, but detect it clearly in CO lines only and not in atomic lines, suggesting that it likely traces a non-axisymmetric structure in the inner disc of CI Tau rather than a massive close-in planet. [ABSTRACT FROM AUTHOR]

We report results of a spectropolarimetric monitoring of the young Sun-like star V1298 Tau based on data collected with the near-infrared spectropolarimeter SPIRou at the Canada–France–Hawaii Telescope between late 2019 and early 2023. Using Zeeman–Doppler Imaging and the Time-dependent Imaging of Magnetic Stars methods on circularly polarized spectra, we reconstructed the large-scale magnetic topology of the star (and its temporal evolution), found to be mainly poloidal and axisymmetric with an average strength varying from 90 to 170 G over the ∼3.5 yr of monitoring. The magnetic field features a dipole whose strength evolves from 85 to 245 G, and whose inclination with respect to the stellar rotation axis remains stable until 2023 where we observe a sudden change, suggesting that the field may undergo a polarity reversal, potentially similar to those periodically experienced by the Sun. Our data suggest that the differential rotation shearing the surface of V1298 Tau is about 1.5 times stronger than that of the Sun. When coupling our data with previous photometric results from K2 and TESS and assuming circular orbits for all four planets, we report a 3.9σ detection of the radial velocity signature of the outermost planet (e), associated with a most probable mass, density, and orbital period of |$M_\mathrm{e}=0.95^{+0.33}_{-0.24}$| MꝜ, |$\rho _\mathrm{e}=1.66^{+0.61}_{-0.48}$| |$\rm g\, cm^{-3}$|⁠ , and P e = 53.0039 ± 0.0001 d, respectively. For the three inner planets, we only derive 99 per cent confidence upper limits on their mass of 0.44, 0.22, and 0.25 MꝜ, for b, c, and d, respectively. [ABSTRACT FROM AUTHOR]

SPIRou is a near-infrared spectropolarimeter and a high-precision velocimeter. The SPIRou Legacy Survey collected data from February 2019 to June 2022, half of the time devoted to a blind search for exoplanets around nearby cool stars. The aim of this paper is to present this program and an overview of its properties, and to revisit the radial velocity (RV) data of two multiplanet systems, including new visits with SPIRou. From SPIRou data, we can extract precise RVs using efficient telluric correction and line-by-line measurement techniques, and we can reconstruct stellar magnetic fields from the collection of polarized spectra using the Zeeman-Doppler imaging method. The stellar sample of our blind search in the solar neighborhood, the observing strategy, the RV noise estimates, chromatic behavior, and current limitations of SPIRou RV measurements on bright M dwarfs are described. In addition, SPIRou data over a 2.5-yr time span allow us to revisit the known multiplanet systems GJ 876 and GJ 1148. For GJ 876, the new dynamical analysis including the four planets is consistent with previous models and confirms that this system is deep in the Laplace resonance and likely chaotic. The large-scale magnetic map of GJ 876 over two consecutive observing seasons is obtained and shows a dominant dipolar field with a polar strength of 30 G, which defines the magnetic environment in which the inner planet with a period of 1.94 days is embedded. For GJ 1148, we refine the known two-planet model. [ABSTRACT FROM AUTHOR]

In this paper, we present an analysis of near-infrared spectropolarimetric and velocimetric data of the young M dwarf AU Mic, collected with SPIRou at the Canada–France–Hawaii telescope from 2019 to 2022, mostly within the SPIRou Legacy Survey. With these data, we study the large- and small-scale magnetic field of AU Mic, detected through the unpolarized and circularly polarized Zeeman signatures of spectral lines. We find that both are modulated with the stellar rotation period (4.86 d), and evolve on a time-scale of months under differential rotation and intrinsic variability. The small-scale field, estimated from the broadening of spectral lines, reaches 2.61 ± 0.05 kG. The large-scale field, inferred with Zeeman–Doppler imaging from Least-Squares Deconvolved profiles of circularly polarized and unpolarized spectral lines, is mostly poloidal and axisymmetric, with an average intensity of 550 ± 30 G. We also find that surface differential rotation, as derived from the large-scale field, is ≃30 per cent weaker than that of the Sun. We detect the radial velocity (RV) signatures of transiting planets b and c, although dwarfed by activity, and put an upper limit on that of candidate planet d, putatively causing the transit-timing variations of b and c. We also report the detection of the RV signature of a new candidate planet (e) orbiting further out with a period of 33.39 ± 0.10 d, i.e. near the 4:1 resonance with b. The RV signature of e is detected at 6.5σ while those of b and c show up at ≃4σ, yielding masses of |$10.2^{+3.9}_{-2.7}$| and |$14.2^{+4.8}_{-3.5}$|  M⊕ for b and c, and a minimum mass of |$35.2^{+6.7}_{-5.4}$|  M⊕ for e. [ABSTRACT FROM AUTHOR]

This paper presents an overview of SPIRou, the new-generation near-infrared spectropolarimeter/precision velocimeter recently installed on the 3.6-m Canada–France–Hawaii Telescope (CFHT). Starting from the two main science goals, i.e. the quest for planetary systems around nearby M dwarfs and the study of magnetized star/planet formation, we outline the instrument concept that was designed to efficiently address these forefront topics, and detail the in-lab and on-sky instrument performances measured throughout the intensive testing phase that SPIRou was submitted to before passing the final acceptance review in early 2019 and initiating science observations. With a central position among the newly started programmes, the SPIRou Legacy Survey (SLS) Large Programme was allocated 300 CFHT nights until at least mid 2022. We also briefly describe a few of the first results obtained in the various science topics that SPIRou started investigating, focusing in particular on planetary systems of nearby M dwarfs, transiting exoplanets and their atmospheres, magnetic fields of young stars, but also on alternate science goals like the atmospheres of M dwarfs and the Earth's atmosphere. We finally conclude on the key role that SPIRou and the CFHT can play in coordination with forthcoming major facilities like the JWST, the ELTs, PLATO, and ARIEL over the decade. [ABSTRACT FROM AUTHOR]

SPIRou is the newest spectropolarimeter and high-precision velocimeter that has recently been installed at the Canada-France-Hawaii Telescope on Maunakea, Hawaii. It operates in the near-infrared and simultaneously covers the 0.98–2.35 μm domain at high spectral resolution. SPIRou is optimized for exoplanet search and characterization with the radial-velocity technique, and for polarization measurements in stellar lines and subsequent magnetic field studies. The host of the transiting hot Jupiter HD 189733 b has been observed during early science runs. We present the first near-infrared spectropolarimetric observations of the planet-hosting star as well as the stellar radial velocities as measured by SPIRou throughout the planetary orbit and two transit sequences. The planetary orbit and Rossiter-McLaughlin anomaly are both investigated and modeled. The orbital parameters and obliquity are all compatible with the values found in the optical. The obtained radial-velocity precision is compatible with about twice the photon-noise estimates for a K2 star under these conditions. The additional scatter around the orbit, of about 8 m s−1, agrees with previous results that showed that the activity-induced scatter is the dominant factor. We analyzed the polarimetric signal, Zeeman broadening, and chromospheric activity tracers such as the 1083nm HeI and the 1282nm Paβ lines to investigate stellar activity. First estimates of the average unsigned magnetic flux from the Zeeman broadening of the FeI lines give a magnetic flux of 290 ± 58 G, and the large-scale longitudinal field shows typical values of a few Gauss. These observations illustrate the potential of SPIRou for exoplanet characterization and magnetic and stellar activity studies. [ABSTRACT FROM AUTHOR]

We present high-resolution near-infrared spectropolarimetric observations using the SPIRou instrument at Canada-France-Hawaii Telescope (CFHT) during a transit of the recently detected young planet AU Mic b, with supporting spectroscopic data from iSHELL at NASA InfraRed Telescope Facility. We detect Zeeman signatures in the Stokes V profiles and measure a mean longitudinal magnetic field of ¯Bℓ = 46.3 ± 0.7 B ¯ ℓ = 46.3 ± 0.7 $ \overline{B}_\ell=46.3\pm0.7 $ G. Rotationally modulated magnetic spots likely cause long-term variations of the field with a slope of dBℓ/dt = −108.7 ± 7.7 G d−1. We apply the cross-correlation technique to measure line profiles and obtain radial velocities through CCF template matching. We find an empirical linear relationship between radial velocity and Bℓ, which allows us to estimate the radial-velocity induced by stellar activity through rotational modulation of spots for the five hours of continuous monitoring of AU Mic with SPIRou. We model the corrected radial velocities for the classical Rossiter-McLaughlin effect, using MCMC to sample the posterior distribution of the model parameters. This analysis shows that the orbit of AU Mic b is prograde and aligned with the stellar rotation axis with a sky-projected spin-orbit obliquity of λ = 0°−15°+18° λ = 0 ° − 15 ° + 18 ° $ {\lambda=0^{\circ}}^{+18^{\circ}}_{-15^{\circ}} $. The aligned orbit of AU Mic b indicates that it formed in the protoplanetary disk that evolved into the current debris disk around AU Mic. [ABSTRACT FROM AUTHOR]

Whereas thousands of transiting giant exoplanets are known today, only a few are well characterized with long orbital periods. Here we present KOI-3680b, a new planet in this category. First identified by the Kepler team as a promising candidate from the photometry of the Kepler spacecraft, we establish here its planetary nature from the radial velocity follow-up secured over 2 yr with the SOPHIE spectrograph at Observatoire de Haute-Provence, France. The combined analysis of the whole dataset allows us to fully characterize this new planetary system. KOI-3680b has an orbital period of 141.2417 ± 0.0001 days, a mass of 1.93 ± 0.20 MJup, and a radius of 0.99 ± 0.07 RJup. It exhibits a highly eccentric orbit (e = 0.50 ± 0.03) around an early G dwarf. KOI-3680b is the transiting giant planet with the longest period characterized so far around a single star; it offers opportunities to extend studies which were mainly devoted to exoplanets close to their host stars, and to compare both exoplanet populations. [ABSTRACT FROM AUTHOR]

We present observations with the planet finder Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) of a selected sample of the most promising radial velocity (RV) companions for high-contrast imaging. Using a Monte Carlo simulation to explore all the possible inclinations of the orbit of wide RV companions, we identified the systems with companions that could potentially be detected with SPHERE. We found the most favourable RV systems to observe are: HD 142, GJ 676, HD 39091, HIP 70849, and HD 30177 and carried out observations of these systems during SPHERE Guaranteed Time Observing. To reduce the intensity of the starlight and reveal faint companions, we used principal component analysis algorithms alongside angular and spectral differential imaging. We injected synthetic planets with known flux to evaluate the self-subtraction caused by our data reduction and to determine the 5σ contrast in the J band versus separation for our reduced images. We estimated the upper limit on detectable companion mass around the selected stars from the contrast plot obtained from our data reduction. Although our observations enabled contrasts larger than 15 mag at a few tenths of arcsec from the host stars, we detected no planets. However, we were able to set upper mass limits around the stars using AMES-COND evolutionary models. We can exclude the presence of companions more massive than 25–28  M Jup around these stars, confirming the substellar nature of these RV companions. [ABSTRACT FROM AUTHOR]

We explore the multiplicity of exoplanet host stars with high-resolution images obtained with VLT/SPHERE. Two different samples of systems were observed: one containing low-eccentricity outer planets, and the other containing high-eccentricity outer planets. We find that 10 out of 34 stars in the high-eccentricity systems are members of a binary, while the proportion is 3 out of 27 for circular systems. Eccentric-exoplanet hosts are, therefore, significantly more likely to have a stellar companion than circular-exoplanet hosts. The median magnitude contrast over the 68 data sets is 11.26 and 9.25, in H and K, respectively, at 0.30 arcsec. The derived detection limits reveal that binaries with separations of less than 50 au are rarer for exoplanet hosts than for field stars. Our results also imply that the majority of high-eccentricity planets are not embedded in multiple stellar systems (24 out of 34), since our detection limits exclude the presence of a stellar companion. We detect the low-mass stellar companions of HD7449 and HD211847, both members of our high-eccentricity sample. HD7449B was already detected and our independent observation is in agreement with this earlier work. HD211847's substellar companion, previously detected by the radial velocity method, is actually a low-mass star seen face-on. The role of stellar multiplicity in shaping planetary systems is confirmed by this work, although it does not appear as the only source of dynamical excitation. [ABSTRACT FROM AUTHOR]

We present new radial velocity measurements for three low-metallicity solar-like stars observed with the SOPHIE spectrograph and its predecessor ELODIE, both installed at the 193 cm telescope of the Haute-Provence Observatory, allowing the detection and characterization of three new giant extrasolar planets in intermediate periods of 1.7 to 3.7 yr. All three stars, HD 17674, HD 42012 and HD 29021 present single giant planetary companions with minimum masses between 0.9 and 2.5 MJup. The range of periods and masses of these companions, along with the distance of their host stars, make them good targets to look for astrometric signals over the lifetime of the new astrometry satellite Gaia. We discuss the preliminary astrometric solutions obtained from the first Gaia data release. [ABSTRACT FROM AUTHOR]

We report results of an extended spectropolarimetric and photometric monitoring of the weakline T Tauri star V830 Tau and its recently detected newborn close-in giant planet. Our observations, carried out within the MaTYSSE (Magnetic Topologies of Young Stars and the Survival of close-in giant Exoplanets) programme, were spread over 91 d, and involved the ESPaDOnS and Narval spectropolarimeters linked to the 3.6-m Canada-France-Hawaii, the 2-m Bernard Lyot, and the 8-m Gemini-North Telescopes. Using Zeeman-Doppler Imaging, we characterize the surface brightness distributions, magnetic topologies, and surface differential rotation of V830 Tau at the time of our observations, and demonstrate that both distributions evolve with time beyond what is expected from differential rotation. We also report that near the end of our observations, V830 Tau triggered one major flare and two weaker precursors, showing up as enhanced redshifted emission in multiple spectral activity proxies. With three different filtering techniques, we model the radial velocity (RV) activity jitter (of semi-amplitude 1.2 km s-1) that V830 Tau generates, successfully retrieve the 68 ± 11 m s-1 RV planet signal hiding behind the jitter, further confirm the existence of V830 Tau b, and better characterize its orbital parameters. We find that the method based on Gaussian-process regression performs best thanks to its higher ability at modelling not only the activity jitter, but also its temporal evolution over the course of our observations, and succeeds at reproducing our RV data down to an rms precision of 35 m s-1. Our result provides new observational constraints on scenarios of star/planet formation and demonstrates the scientific potential of large-scale searches for close-in giant planets around T Tauri stars. [ABSTRACT FROM AUTHOR]

Sirius has always attracted a lot of scientific interest, especially after the discovery of a companion white dwarf at the end of the 19th century.Very early on, the existence of a potential third bodywas put forward to explain some of the observed properties of the system.We present new coronagraphic observations obtained with VLT/SPHERE (Very Large Telescope/Spectro- Polarimetric High-contrast Exoplanet REsearch) that explore, for the very first time, the innermost regions of the system down to 0.2 arcsec(0.5 au) from Sirius A. Our observations cover the near-infrared from 0.95 to 2.3 µmand they offer the best on-sky contrast ever reached at these angular separations. After detailing the steps of our SPHERE/IRDIFS data analysis, we present a robust method to derive detection limits for multispectral data from high-contrast imagers and spectrographs. In terms of raw performance, we report contrasts of 14.3 mag at 0.2 arcsec, ˜16.3 mag in the 0.4-1.0 arcsec range and down to 19 mag at 3.7 arcsec. In physical units, our observations are sensitive to giant planets down to 11 MJup at 0.5 au, 6-7 MJup in the 1-2 au range and ˜4 MJup at 10 au. Despite the exceptional sensitivity of our observations, we do not report the detection of additional companions around Sirius A. Using a Monte Carlo orbital analysis, we show that we can reject, with about 50 per cent probability, the existence of an 8 MJup planet orbiting at 1 au. [ABSTRACT FROM AUTHOR]

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 ms-1 precision in radial velocity mea- surements 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 M&#7609 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. [ABSTRACT FROM AUTHOR]

Exoplanets in extremely close-in orbits are immersed in a local interplanetary medium (i.e. the stellar wind) much denser than the local conditions encountered around the Solar system planets. The environment surrounding these exoplanets also differs in terms of dynamics (slower stellar winds, but higher Keplerian velocities) and ambient magnetic fields (likely higher for host stars more active than the Sun). Here, we quantitatively investigate the nature of the interplanetary media surrounding the hot Jupiters HD 46375b, HD 73256b, HD 102195b, HD 130322b and HD 179949b. We simulate the three-dimensional winds of their host stars, in which we directly incorporate their observed surface magnetic fields. With that, we derive mass-loss rates (1.9-8.0 × 10-13 M☉ yr-1) and the wind properties at the position of the hot Jupiters' orbits (temperature, velocity, magnetic field intensity and pressure). We show that these exoplanets' orbits are supermagnetosonic, indicating that bow shocks are formed surrounding these planets. Assuming planetary magnetic fields similar to Jupiter's, we estimate planetary magnetospheric sizes of 4.1-5.6 planetary radii. We also derive the exoplanetary radio emission released in the dissipation of the stellar wind energy. We find radiofluxes ranging from 0.02 to 0.13 mJy, which are challenging to be observed with present-day technology, but could be detectable with future higher sensitivity arrays (e.g. Square Kilometre Array). Radio emission from systems having closer hot Jupiters, such as from τ Boo b or HD 189733b, or from nearby planetary systems orbiting young stars, are likely to have higher radiofluxes, presenting better prospects for detecting exoplanetary radio emission. [ABSTRACT FROM AUTHOR]

Radial-velocity observations of Kepler candidates obtained with the SOPHIE and HARPS-N spectrographs have permitted unveiling the nature of the five giant planets Kepler-41b, Kepler-43b, Kepler-44b, Kepler-74b, and Kepler-75b, the massive companion Kepler-39b, and the brown dwarf KOI-205b. These companions were previously characterized with long-cadence (LC) Kepler data. Here we aim at refining the parameters of these transiting systems by i) modelling the published radial velocities and Kepler short-cadence (SC) data that provide a much better sampling of the transits; ii) performing new spectral analyses of the SOPHIE and ESPaDOnS spectra, after improving our procedure for selecting and co-adding the SOPHIE spectra of faint stars (Kp ≳ 14); and iii) improving stellar rotation periods hence stellar age estimates through gyrochronology, when possible, by using all the available LC data up to quarter Q17. Posterior distributions of the system parameters were derived with a differential evolution Markov chain Monte Carlo approach. Our main results are as follows: a) Kepler-41b is significantly larger and less dense than previously found because a lower orbital inclination is favoured by SC data. This also affects the determination of the geometric albedo that is lower than previously derived: Ag < 0:135; b) Kepler-44b is moderately smaller and denser than reported in the discovery paper, as a consequence of the slightly shorter transit duration found with SC data; c) good agreement was achieved with published Kepler-43, Kepler-75, and KOI-205 system parameters, although the host stars Kepler-75 and KOI-205 were found to be slightly richer in metals and hotter, respectively; d) the previously reported non-zero eccentricities of Kepler-39b and Kepler-74b might be spurious. If their orbits were circular, the two companions would be smaller and denser than in the eccentric case. The radius of Kepler-39b is still larger than predicted by theoretical isochrones. Its parent star is hotter and richer in metals than previously determined. [ABSTRACT FROM AUTHOR]

Context. The new planet finder for the Very Large Telescope (VLT), the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE), just had its first light in Paranal. A dedicated instrument for the direct detection of planets, SPHERE, is composed of a polametric camera in visible light, the Zurich IMager POLarimeter (ZIMPOL), and two near-infrared sub-systems: the Infra-Red Dual-beam Imager and Spectrograph (IRDIS), a multi-purpose camera for imaging, polarimetry, and long-slit spectroscopy, and the integral field spectrograph (IFS), an integral field spectrograph. Aims. We present the results obtained from the analysis of data taken during the laboratory integration and validation phase, after the injection of synthetic planets. Since no continuous field rotation could be performed in the laboratory, this analysis presents results obtained using reduction techniques that do not use the angular di erential imaging (ADI) technique. Methods. To perform the simulations, we used the instrumental point spread function (PSF) and model spectra of L and T-type objects scaled in contrast with respect to the host star.We evaluated the expected error in astrometry and photometry as a function of the signal to noise of companions, after spectral di erential imaging (SDI) reduction for IRDIS and spectral deconvolution (SD) or principal component analysis (PCA) data reductions for IFS. Results. We deduced from our analysis, for example, that βPicb, a 12 Myr old planet of ∼10 MJup and semi-major axis of 9-10 AU, would be detected with IRDIS with a photometric error of 0.16 mag and with a relative astrometric position error of 1.1 mas.With IFS, we could retrieve a spectrum with error bars of about 0.15 mag on each channel and astrometric relative position error of 0.6 mas. For a fainter object such as HR8799d, a 13 MJup planet at a distance of 27 AU, IRDIS could obtain a relative astrometric error of 3 mas. [ABSTRACT FROM AUTHOR]

The characterization 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 MJup. They are located in the low-mass range of known transiting, giant planets. KOI-192b has a similar mass (0.29 MJup) but a longer orbital period of 10.3 days. This places it in a domain where only a few planets are known. KOI-830b, finally, with a mass of 1.27 MJup 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 RJup, 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 the 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 datasets allow us tofully characterize the four planetary systems. These new objects increase the number of well-characterized 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 instead a false positive. [ABSTRACT FROM AUTHOR]

The CoRoT satellite has provided high-precision photometric light curves for more than 163 000 stars and found several hundreds of transiting systems compatible with a planetary scenario. If ground-based velocimetric observations are the best way to identify the actual planets among many possible configurations of eclipsing binary systems, recent transit surveys have shown that it is not always within reach of the radial-velocity detection limits. In this paper, we present a transiting exoplanet candidate discovered by CoRoT whose nature cannot be established from ground-based observations, and where extensive analyses are used to validate the planet scenario. They are based on observing constraints from radial-velocity spectroscopy, adaptive optics imaging and the CoRoT transit shape, as well as from priors on stellar populations, planet and multiple stellar systems frequency. We use the fully Bayesian approach developed in the pastis (Planet Analysis and Small Transit Investigation Software) analysis software, and conclude that the planet scenario is at least 1400 times more probable than any other false-positive scenario. The primary star is a metallic solar-like dwarf, with Ms = 1.099 ± 0.049 M⊙ and Rs = 1.136$^{+0.038}_{-0.090}$ R⊙. The validated planet has a radius of Rp = 4.88$^{+0.17}_{-0.39}$ R⊕ and mass less than 49 M⊕. Its mean density is smaller than 2.56 g cm−3 and orbital period is 9.7566 ± 0.0012 d. This object, called CoRoT-22 b, adds to a large number of validated Kepler planets. These planets do not have a proper measurement of the mass but allow statistical characterization of exoplanets population. [ABSTRACT FROM AUTHOR]

Since the discovery of the transiting super-Earth CoRoT-7b, several investigations have yielded different results for the number and masses of planets present in the system, mainly owing to the star's high level of activity. We re-observed CoRoT-7 in 2012 January with both HARPS and CoRoT, so that we now have the benefit of simultaneous radial-velocity and photometric data. This allows us to use the off-transit variations in the star's light curve to estimate the radial-velocity variations induced by the suppression of convective blueshift and the flux blocked by starspots. To account for activity-related effects in the radial velocities which do not have a photometric signature, we also include an additional activity term in the radial-velocity model, which we treat as a Gaussian process with the same covariance properties (and hence the same frequency structure) as the light curve. Our model was incorporated into a Monte Carlo Markov Chain in order to make a precise determination of the orbits of CoRoT-7b and CoRoT-7c. We measure the masses of planets b and c to be 4.73 ± 0.95 and 13.56 ± 1.08 M⊕, respectively. The density of CoRoT-7b is (6.61 ± 1.72)(Rp/1.58 R⊕)−3 g cm−3, which is compatible with a rocky composition. We search for evidence of an additional planet d, identified by previous authors with a period close to 9 d. We are not able to confirm the existence of a planet with this orbital period, which is close to the second harmonic of the stellar rotation at ∼7.9 d. Using Bayesian model selection, we find that a model with two planets plus activity-induced variations is most favoured. [ABSTRACT FROM PUBLISHER]

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]

Aims. In the context of the search for extrasolar planets and brown dwarfs around early-type main-sequence stars we present the detection of a giant planet around the young F-type star HD113337. We estimated the age of the system to be 150-50+100 Myr. Interestingly, an infrared excess attributed to a cold debris disk was previously detected around this star. Methods. We used the SOPHIE spectrograph on the 1.93m telescope at Observatoire de Haute-Provence to obtain ~300 spectra over six years. We used our tool dedicated to the spectra analysis of A and F stars to derive the radial velocity variations. Results. The data reveal a period of 324.0-3.3+1.7 days that we attribute to a giant planet with a minimum mass of 2.83 ± 0.24 MJup in an eccentric orbit with e = 0.46 ± 0.04. A long-term quadratic drift, which we assign to be probably of stellar origin, is superimposed on the Keplerian solution. [ABSTRACT FROM AUTHOR]

We report the discovery of a long-period brown-dwarf transiting companion of the solar-type star KOI-415. The transits were detected by the Kepler space telescope. We conducted Doppler measurements using the SOPHIE spectrograph at the Observatoire de Haute- Provence. The photometric and spectroscopic signals allow us to characterize a 62.14 ± 2.69 MJup brown-dwarf companion of an evolved 0.94 ± 0.06 M☉ star in a highly eccentric orbit of P = 166.78805 ± 0.00022 days and e = 0.698 ± 0.002. The radius of KOI-415 b is 0.79+0.12 -0.07RJup, a value that is compatible with theoretical predictions for a 10 Gyr, low-metallicity and non-irradiated object. [ABSTRACT FROM AUTHOR]

Context. Studies of transiting extrasolar planets are of key importance for understanding the nature of planets outside our solar system because their masses, diameters, and bulk densities can be measured. An important part of transit-search programmes is the removal of false-positives. In the case of the CoRoT space mission, the majority of the false-positives are removed by a detailed analysis of the light curves and by seeing-limited imaging in- and out-of-transit. However, the critical question is how many of the candidates that passed all these tests are false-positives. Such false-positives can be caused by eclipsing binaries, which are either related or unrelated to the targets. Aims. For our study we selected 25 CoRoT candidates that have already been screened against false-positives using detailed analysis of the light curves and seeing-limited imaging, which has transits that are between 0.7 and 0.05% deep. Our aim is to search for companion candidates that had not been recognized in previous observations. Methods. We observed 20 candidates with the adaptive optics imager NaCo and 18 with the high-resolution infrared spectrograph CRIRES. Results. We found previously unknown stars within 2″ of the targets in seven of the candidates. All of these are too faint and too close to the targets to have been previously detected with seeing-limited telescopes in the optical. Our study thus leads to the surprising results that if we remove all candidates excluded by the sophisticated analysis of the light-curve, as well as carrying out deep imaging with seeing-limited telescopes, still 28-35% of the remaining candidates are found to possess companions that are bright enough to be false-positives. Conclusions. Given that the companion candidates cluster around the targets and that the J - K colours are consistent with physical companions, we conclude that the companion candidates are more likely to be physical companions rather than unrelated field stars. [ABSTRACT FROM AUTHOR]

The meter-per-second precision achieved by today's velocimeters enables us to search for 1-10 M⊕ planets in the habitable zone of cool stars. This paper reports on the detection of three planets orbiting GJ 163 (HIP 19394), a M3 dwarf monitored by our ESO/HARPS search for planets. We made use of the HARPS spectrograph to collect 150 radial velocities of GJ 163 over a period of eight years. We searched the radial-velocity time series for coherent signals and found five distinct periodic variabilities. We investigated the stellar activity and called into question the planetary interpretation for two signals. Before more data can be acquired we concluded that at least three planets are orbiting GJ 163. They have orbital periods of Pb = 8:632 ± 0:002, Pc = 25:63 ± 0:03, and Pd = 604 ± 8 days and minimum masses m sin i = 10:6 ± 0:6, 6:8 ± 0:9, and 29 ± 3 M⊕, respectively. We hold our interpretations for the two additional signals with periods P(e) = 19:4 and P(f) = 108 days. The inner pair presents an orbital period ratio of 2:97, but a dynamical analysis of the system shows that it lays outside the 3:1 mean motion resonance. The planet GJ 163c, in particular, is a super-Earth with an equilibrium temperature of Teq = (302 ± 10)(1 - A)1/4 K and may lie in the so-called habitable zone for albedo values (A = 0:34-0:89) moderately higher than that of Earth (A⊕ = 0:2-0:3). [ABSTRACT FROM AUTHOR]

Since the discovery of the transiting Super-Earth CoRoT-7b, several investigations have been made of the number and precise masses of planets present in the system, but they all yield different results, owing to the star's high level of activity. Radial velocity (RV) variations induced by stellar activity therefore need to be modelled and removed to allow a reliable detection of all planets in the system. We re-observed CoRoT-7 in January 2012 with both HARPS and the CoRoT satellite, so that we now have the benefit of simultaneous RV and photometric data. We fitted the off-transit variations in the CoRoT lightcurve using a harmonic decomposition similar to that implemented in Queloz et al. (2009). This fit was then used to model the stellar RV contribution, according to the methods described by Aigrain et al. (2011). This model was incorporated into a Monte Carlo Markov Chain in order to make a precise determination of the orbits of CoRoT-7b and CoRoT-7c. We also assess the evidence for the presence of one or two additional planetary companions. [ABSTRACT FROM PUBLISHER]

We report the discovery by the WASP transit survey of a highly-irradiated, massive (2.242 ± 0.080 MJup) planet which transits a bright (V = 10.6), evolved F8 star every 2.9 days. The planet, WASP-71b, is larger than Jupiter (1.46 ± 0.13 RJup), but less dense (0.71 ± 0.16 ρJup). We also report spectroscopic observations made during transit with the CORALIE spectrograph, which allow us to make a highly-significant detection of the Rossiter-McLaughlin effect. We determine the sky-projected angle between the stellar-spin and planetary-orbit axes to be λ = 20.1 ± 9.7 degrees, i.e. the system is “aligned”, according to the widely-used alignment criteria that systems are regarded as misaligned only when λ is measured to be greater than 10 degrees with 3-σ confidence. WASP-71, with an effective temperature of 6059 ± 98 K, therefore fits the previously observed pattern that only stars hotter than 6250 K are host to planets in misaligned orbits. We emphasise, however, that λ is merely the sky-projected obliquity angle; we are unable to determine whether the stellar-spin and planetary-orbit axes are misaligned along the line-of-sight. With a mass of 1.56 ± 0.07 M⊙, WASP-71 was previously hotter than 6250 K, and therefore might have been significantly misaligned in the past. If so, the planetary orbit has been realigned, presumably through tidal interactions with the cooling star’s growing convective zone. [ABSTRACT FROM AUTHOR]

The vast diversity of planetary systems detected to date is defying our capability of understanding their formation and evolution. Well-defined volume-limited surveys are the best tool at our disposal to tackle the problem, via the acquisition of robust statistics of the orbital elements. We are using the HARPS spectrograph to conduct our survey of ≈850 nearby solar-type stars, and in the course of the past nine years we have monitored the radial velocity of HD 103774, HD 109271, and BD-061339. In this work we present the detection of five planets orbiting these stars, with msin (i) between 0.6 and 7 Neptune masses, four of which are in two multiple systems, comprising one super-Earth and one planet within the habitable zone of a late-type dwarf. Although for strategic reasons we chose efficiency over precision in this survey, we have the capability to detect planets down to the Neptune and super-Earth mass range as well as multiple systems, provided that enough data points are made available. [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]

Context. With now more than 20 exoplanets discovered by CoRoT, it has often been considered strange that so many of them are orbiting F-stars, and so few of them K- or M-stars. Up to now, studies of the relation between the frequency of extrasolar planets and the spectral types, or masses of their host stars has been the realm of radial velocity surveys. Although transit search programs are mostly sensitive to short-period planets, they are ideal for verifying these results. This is because transit search programs have different selection biases than radial velocity surveys. To determine the frequency of planets as a function of stellar mass, we also have to characterize the sample of stars that was observed. Aims. We study the stellar content of the CoRoT-fields IRa01, LRa01 (=LRa06), and LRa02 by determining the spectral types of 11?466 stars. Nine planet-host stars have already been identified in these fields. Determing the spectral types of thousands of stars of which CoRoT obtained high-precision light-curves also makes a wide variety of other research projects possible. Methods. We used spectra obtained with the multi-object spectrograph AAOmega and derived the spectral types by using template spectra with well-known parameters. Results. We find that 34.8 ± 0.7% of the stars observed by CoRoT in these fields are F-dwarfs, 15.1 ± 0.5% G-dwarfs, and 5.0 ± 0.3% K-dwarfs. We conclude that the apparent lack of exoplanets of K- and M-stars is explained by the relatively small number of these stars in the observed sample. We also show that the apparently large number of planets orbiting F-stars is similarly explained by the large number of such stars in these fields. Given the number of F-stars, we would have expected to find even more F-stars with planets. Our study also shows that the difference between the sample of stars that CoRoT observes and a sample of randomly selected stars is relatively small, and that the yield of CoRoT specifically is the detection one hot Jupiter amongst 2100 ± 700 stars. Conclusions. We conclude that transit search programs can be used to study the relation between the frequency of planets and the mass of the host stars, and that the results obtained so far generally agree with those of radial velocity programs. [ABSTRACT FROM AUTHOR]

Context. The mass domain where massive extrasolar planets and brown dwarfs lie is still poorly understood. Indeed, not even a clear dividing line between massive planets and brown dwarfs has been established yet. This is partly because these objects are very scarce in close orbits around solar-type stars, the so-called brown dwarf desert. Owing to this, it has proven difficult to set up a strong observational base with which to compare models and theories of formation and evolution. Aims. We search to increase the current sample of massive sub-stellar objects with precise orbital parameters, and to constrain the true mass of detected sub-stellar candidates. Methods. The initial identification of sub-stellar candidates was made using precise radial velocity measurements obtained with the SOPHIE spectrograph at the 1.93-m telescope of the Haute-Provence Observatory. Subsequent characterisation of these candidates, with the principal aim of identifying stellar companions in low-inclination orbits, was made by means of different spectroscopic diagnostics such as the measurement of the bisector velocity span and the study of the correlation mask effect. With this objective, we also employed astrometric data from the Hipparcos mission, and a novel method of simulating stellar cross-correlation functions. Results. Seven new objects with minimum masses between ∼10 MJup and ∼90 MJup are detected. Out of these, two are identified as low-mass stars in low-inclination orbits, and two others have masses below the theoretical deuterium-burning limit, and are therefore planetary candidates. The remaining three are brown dwarf candidates; the current upper limits for their the masses do not allow us to conclude on their nature. Additionally, we have improved the parameters of an already-known brown dwarf (HD 137510b), confirmed by astrometry. [ABSTRACT FROM AUTHOR]

We report the discovery of two new transiting hot Jupiters, KOI-135b and KOI-204b, which were previously identified as planetary candidates by the Kepler team, and independently confirm the planetary nature of Kepler-17b, recently announced by Désert et al. (2011, ApJS, 197, 14). Radial-velocity measurements, taken with the SOPHIE spectrograph at the Observatoire de Haute-Provence (France), and Kepler photometry (Q1 and Q2 data) were used to derive the orbital, stellar, and planetary parameters. KOI-135b and KOI-204b orbit their parent stars in ∼3.02 and 3.25 days, respectively. They have approximately the same radius, Rp = 1.20 ± 0.06 RJup and 1.24 ± 0.07 RJup, but different masses Mp = 3.23 ± 0.19 MJup and 1.02 ± 0.07 MJup. As a consequence, their bulk densities differ by a factor of four, ρp = 2.33 ± 0.36 g cm-3 (KOI-135b) and 0.65 ± 0.12 g cm-3 (KOI-204b), meaning that their interior structures are different. All three planets orbit metal-rich stars with [Fe/H] ∼ 0.3 dex. Our SOPHIE spectra of Kepler-17 were used both to measure the radial-velocity variations and to determine the stellar atmospheric parameters, allowing us to refine the characterisation of the planetary system. In particular we found the radial-velocity semi-amplitude and the stellar mass to be respectively slightly smaller and larger than in Désert et al. These two quantities, however, compensate and lead to a fully consistent planetary mass. Our analysis gives Mp = 2.47 ± 0.10 MJup and Rp = 1.33 ± 0.04 RJup. We found evidence of a younger age for this planetary system, t < 1.8 Gyr, which is supported by both evolutionary tracks and gyrochronology. Finally, we confirm the detection of the optical secondary eclipse by Désert et al. and also find the brightness phase variation with the Q1 and Q2 Kepler data. The latter indicates a low redistribution of stellar heat to the night side (<16% at 1-σ), if the optical planetary occultation comes entirely from thermal flux. The geometric albedo is Ag < 0.12 (1-σ). [ABSTRACT FROM AUTHOR]

We report the detection of CoRoT-23b, a hot Jupiter transiting in front of its host star with a period of 3.6314 ± 0.0001 days. This planet was discovered thanks to photometric data secured with the CoRoT satellite, combined with spectroscopic radial velocity (RV) measurements. A photometric search for possible background eclipsing binaries conducted at CFHT and OGS concluded with a very low risk of false positives. The usual techniques of combining RV and transit data simultaneously were used to derive stellar and planetary parameters. The planet has a mass of Mp = 2.8±0.3 MJup, a radius of Rpl= 1.05 ± 0.13 RJup, a density of ≈3 gcm-3. RV data also clearly reveal a nonzero eccentricity of e = 0.16 ± 0.02. The planet orbits a mature G0 main sequence star of V = 15.5 mag, with a mass M⋆ = 1.14 ± 0.08 M☉, a radius R⋆ = 1. 61 ± 0.18 R☉ and quasi-solar abundances. The age of the system is evaluated to be 7 Gyr, not far from the transition to subgiant, in agreement with the rather large stellar radius. The two features of a significant eccentricity of the orbit and of a fairly high density are fairly uncommon for a hot Jupiter. The high density is, however, consistent with a model of contraction of a planet at this mass, given the age of the system. On the other hand, at such an age, circularization is expected to be completed. In fact, we show that for this planetary mass and orbital distance, any initial eccentricity should not totally vanish after 7 Gyr, as long as the tidal quality factor Qp is more than a few 105, a value that is the lower bound of the usually expected range. Even if CoRoT-23b features a density and an eccentricity that are atypical of a hot Jupiter, it is thus not an enigmatic object. [ABSTRACT FROM AUTHOR]

HD 189733 is a K2 dwarf, orbited by a giant planet at 8.8 stellar radii. In order to study magnetospheric interactions between the star and the planet, we explore the large-scale magnetic field and activity of the host star. We collected spectra using the ESPaDOnS and the NARVAL spectropolarimeters, installed at the 3.6-m Canada–France–Hawaii telescope and the 2-m Telescope Bernard Lyot at Pic du Midi, during two monitoring campaigns (2007 June and 2008 July). HD 189733 has a mainly toroidal surface magnetic field, having a strength that reaches up to 40 G. The star is differentially rotating, with latitudinal angular velocity shear of , corresponding to equatorial and polar periods of and , respectively. The study of the stellar activity shows that it is modulated mainly by the stellar rotation (rather than by the orbital period or the beat period between the stellar rotation and the orbital periods). We report no clear evidence of magnetospheric interactions between the star and the planet. We also extrapolated the field in the stellar corona and calculated the planetary radio emission expected for HD 189733b, given the reconstructed field topology. The radio flux we predict in the framework of this model is time variable and potentially detectable with LOFAR. [ABSTRACT FROM AUTHOR]