Search

Planets with radii between that of the Earth and Neptune (hereafter referred to as ‘sub-Neptunes’) are found in close-in orbits around more than half of all Sun-like stars1,2. However, their composition, formation and evolution remain poorly understood3. The study of multiplanetary systems offers an opportunity to investigate the outcomes of planet formation and evolution while controlling for initial conditions and environment. Those in resonance (with their orbital periods related by a ratio of small integers) are particularly valuable because they imply a system architecture practically unchanged since its birth. Here we present the observations of six transiting planets around the bright nearby star HD 110067. We find that the planets follow a chain of resonant orbits. A dynamical study of the innermost planet triplet allowed the prediction and later confirmation of the orbits of the rest of the planets in the system. The six planets are found to be sub-Neptunes with radii ranging from 1.94R⊕to 2.85R⊕. Three of the planets have measured masses, yielding low bulk densities that suggest the presence of large hydrogen-dominated atmospheres.

Planetary rings are observed not only around giant planets1, but also around small bodies such as the Centaur Chariklo2and the dwarf planet Haumea3. Up to now, all known dense rings were located close enough to their parent bodies, being inside the Roche limit, where tidal forces prevent material with reasonable densities from aggregating into a satellite. Here we report observations of an inhomogeneous ring around the trans-Neptunian body (50000) Quaoar. This trans-Neptunian object has an estimated radius4of 555 km and possesses a roughly 80-km satellite5(Weywot) that orbits at 24 Quaoar radii6,7. The detected ring orbits at 7.4 radii from the central body, which is well outside Quaoar’s classical Roche limit, thus indicating that this limit does not always determine where ring material can survive. Our local collisional simulations show that elastic collisions, based on laboratory experiments8, can maintain a ring far away from the body. Moreover, Quaoar’s ring orbits close to the 1/3 spin–orbit resonance9with Quaoar, a property shared by Chariklo’s2,10,11and Haumea’s3rings, suggesting that this resonance plays a key role in ring confinement for small bodies.

Aims. We report the discovery of very shallow ($\Delta F/F \approx 3.4\times 10^{-4}$), periodic dips in the light curve of an active $V = 11.7$G9V star observed by the CoRoT  satellite, which we interpret as caused by a transiting companion. We describe the 3-colour CoRoT data and complementary ground-based observations that support the planetary nature of the companion.

We report on an intensive observational campaign carried out with HARPS at the 3.6 m telescope at La Silla on the star CoRoT-7. Additional simultaneous photometric measurements carried out with the Euler Swiss telescope have demonstrated that the observed radial velocity variations are dominated by rotational modulation from cool spots on the stellar surface. Several approaches were used to extract the radial velocity signal of the planet(s) from the stellar activity signal. First, a simple pre-whitening procedure was employed to find and subsequently remove periodic signals from the complex frequency structure of the radial velocity data. The dominant frequency in the power spectrum was found at 23  days, which corresponds to the rotation period of CoRoT-7. The 0.8535 day period of CoRoT-7b planetary candidate was detected with an amplitude of 3.3 m s-1. Most other frequencies, some with amplitudes larger than the CoRoT-7b signal, are most likely associated with activity. A second approach used harmonic decomposition of the rotational period and up to the first three harmonics to filter out the activity signal from radial velocity variations caused by orbiting planets. After correcting the radial velocity data for activity, two periodic signals are detected: the CoRoT-7b  transit period and a second one with a period of 3.69 days and an amplitude of 4 m s-1. This second signal was also found in the pre-whitening analysis. We attribute the second signal to a second, more remote planet CoRoT-7c . The orbital solution of both planets is compatible with circular orbits. The mass of CoRoT-7b is $4.8\pm0.8$($M_{\oplus}$) and that of CoRoT-7c is $8.4\pm 0.9$($M_{\oplus}$), assuming both planets are on coplanar orbits. We also investigated the false positive scenario of a blend by a faint stellar binary, and this may be rejected by the stability of the bisector on a nightly scale. According to their masses both planets belong to the super-Earth planet category. The average density of CoRoT-7b is $\rho=5.6\pm 1.3\mathrm{\,g\,cm^{-3}}$, similar to the Earth. The CoRoT-7 planetary system provides us with the first insight into the physical nature of short period super-Earth planets recently detected by radial velocity surveys. These planets may be denser than Neptune and therefore likely made of rocks like the Earth, or a mix of water ice and rocks.

We present VLT eclipse photometry for the giant planet CoRoT-1b. We observed a transit in the R-band filter and an occultation in a narrow filter centered on 2.09 μm. Our analysis of this new photometry and published radial velocities, in combination with stellar-evolutionary modeling, leads to a planetary mass and radius of 1.07$^{+0.13}_{-0.18}$MJupand 1.45$^{+0.07}_{-0.13}$RJup, confirming the very low density previously deduced from CoRoT photometry. The large occultation depth that we measure at 2.09 μm (0.278$^{+0.043}_{-0.066}\%$) is consistent with thermal emission and is better reproduced by an atmospheric model with no redistribution of the absorbed stellar flux to the night side of the planet.

Aims. We present here the list of planetary transit candidates detected in the first long run observed by CoRoT: LRc01, towards the galactic center in the direction of Aquila, which lasted from May to October 2007.

Aims. The CoRoT space mission continues to photometrically monitor about 12 000 stars in its field-of-view for a series of target fields to search for transiting extrasolar planets ever since 2007. Deep transit signals can be detected quickly in the “alarm-mode” in parallel to the ongoing target field monitoring. CoRoT's first planets have been detected in this mode.

With the release of CoRoT lightcurves of the Initial Run IRa01, 50 transiting planetary candidates have been published in a companion paper. About twenty of them were identified as binary stars from the CoRoT lightcurve itself. Complementary observations were conducted for 29 candidates, including ground-based photometry and radial-velocity measurements. Two giant planets were identified and fully characterized. Nineteen binaries are recognized, from which 10 are background eclipsing binaries in the CoRoT mask or triple systems, diluted by the main CoRoT target. Eight cases remain of unclear origin, one of them still being a planetary candidate. Comparison with simulations shows that the actual threshold of confirmed planet detection in this field does not yet fulfill the expectations, and a number of reasons are invoked, like the ranking process based on lightcurve analyses, and the strategy and limits of follow-up observations for targets fainter than magnitude 15.

Context. The CoRoT satellite searches for planets by applying the transit method, monitoring up to 12 000 stars in the galactic plane for 150 days in each observing run. This search is contaminated by a large fraction of false positives, caused by different eclipsing binary configurations that might be confused with a transiting planet.

The motivation, techniques and performance of the ground-based photometric follow-up of transit detections by the CoRoT space mission are presented. Its principal raison d'êtrearises from the much higher spatial resolution of common ground-based telescopes in comparison to CoRoT's cameras. This allows the identification of many transit candidates as arising from eclipsing binaries that are contaminating CoRoT's lightcurves, even in low-amplitude transit events that cannot be detected with ground-based obervations. For the ground observations, “on” – “off” photometry is now largely employed, in which only a short timeseries during a transit and a section outside a transit is observed and compared photometrically. CoRoTplanet candidates' transits are being observed by a dedicated team with access to telescopes with sizes ranging from 0.2 to 2 m. As an example, the process that led to the rejection of contaminating eclipsing binaries near the host star of the Super-Earth planet CoRoT-7b is shown. Experiences and techniques from this work may also be useful for other transit-detection experiments, when the discovery instrument obtains data with a relatively low angular resolution.

Context. The CoRoTspace mission routinely provides high-precision photometric measurements of thousands of stars that have been continuously observed for months.

Aims. The CoRoT satellite has announced its fourth transiting planet (Aigrain et al. 2008, A&A, 488, L43) with space photometry. We describe and analyse complementary observations of this system performed to establish the planetary nature of the transiting body and to estimate the fundamental parameters of the planet and its parent star.

CoRoT, the first space-based transit search, provides ultra-high-precision light curves with continuous time-sampling over periods of up to 5 months. This allows the detection of transiting planets with relatively long periods, and the simultaneous study of the host star's photometric variability. In this Letter, we report the discovery of the transiting giant planet CoRoT-Exo-4b and use the CoRoT light curve to perform a detailed analysis of the transit and determine the stellar rotation period. The CoRoT light curve was pre-processed to remove outliers and correct for orbital residuals and artefacts due to hot pixels on the detector. After removing stellar variability about each transit, the transit light curve was analysed to determine the transit parameters. A discrete autocorrelation function method was used to derive the rotation period of the star from the out-of-transit light curve. We determine the periods of the planetary orbit and star's rotation of 9.20205 ±0.00037 and 8.87 ±1.12 days respectively, which is consistent with this being a synchronised system. We also derive the inclination, $i = 90.00_{\rm -0.085}^{+0.000}$in degrees, the ratio of the orbital distance to the stellar radius, $a/R_{\rm s} = 17.36_{-0.25}^{+0.05}$, and the planet-to-star radius ratio $R_{\rm p}/R_{\rm s}=0.1047_{-0.0022}^{+0.0041}$. We discuss briefly the coincidence between the orbital period of the planet and the stellar rotation period and its possible implications for the system's migration and star-planet interaction history.

By re-processing the data of the second season of the OGLE survey for planetary transits and adding new mesurements on the same fields gathered in subsequent years with the OGLE telescope, we have identified 23 new transit candidates, recorded as OGLE-TR-178 to OGLE-TR-200. We studied the nature of these objects with the FLAMES/UVES multi-fiber spectrograph on the VLT. One of the candidates, OGLE-TR-182, was confirmed as a transiting gas giant planet on a 4-day orbit. We characterised it with further observations using the FORS1 camera and UVES spectrograph on the VLT. OGLE-TR-182b is a typical “hot Jupiter” with an orbital period of 3.98 days, a mass of $1.01 \pm 0.15~M_{\rm Jup}$and a radius of 1.13$^{+0.24}_{-0.08}~R_{\rm Jup}$. Confirming this transiting planet required a large investment in telescope time with the best instruments available, and we comment on the difficulty of the confirmation process for transiting planets in the OGLE survey. We delineate the zone were confirmation is difficult or impossible, and discuss the implications for the CoRoT space mission in its quest for transiting telluric planets.

We report high-precision transit photometry for the recently detected planet HD 17156b. Using these new data with previously published transit photometry and radial velocity measurements, we perform a combined analysis based on a Markov Chain Monte Carlo approach. The resulting mass $M_{\rm p} = 3.09^{+0.22}_{-0.17}~M_{\rm Jup}$and radius $R_{\rm p} = 1.23^{+0.17}_{-0.20}$RJupfor the planet places it at the outer edge of the density distribution of known transiting planets with $\rho_{\rm p} = 1.66^{+1.37}_{-0.60}$$\rho_{\rm Jup}$. The obtained transit ephemeris is $T_{\rm Tr} = 2\,454\,438.48271^{+0.00077}_{-0.00057} + N \times 21.21747^{+0.00070}_{-0.00067}$BJD. The derived plausible tidal circularization time scales for HD 17156b are larger than the age of the host star. The measured high orbital eccentricity $e = 0.6719^{+0.0052}_{-0.0063}$can thus not be interpreted as the clear sign of the presence of another body in the system.

Context. The CoRoT mission, a pioneer in exoplanet searches from space, has completed its first 150 days of continuous observations of ~12 000 stars in the galactic plane. An analysis of the raw data identifies the most promising candidates and triggers the ground-based follow-up.

Context. The pioneer space mission for photometric planet searches, CoRoT, steadily monitors about 12 000 stars in each of its fields of view. Transit candidates can be detected early in the processing of the data and before the end of a run of observation.

We present Spitzer Space Telescopeinfrared photometry of a secondary eclipse of the hot Neptune GJ 436 b. The observations were obtained using the 8-μm band of the InfraRed Array Camera (IRAC). The data spanning the predicted time of secondary eclipse show a clear flux decrement with the expected shape and duration. The observed eclipse depth of 0.58 mmag allows us to estimate a blackbody brightness temperature of Tp= 717 ±35 K at 8 μm. We compare this infrared flux measurement to a model of the planetary thermal emission, and show that this model reproduces properly the observed flux decrement. The timing of the secondary eclipse confirms the non-zero orbital eccentricity of the planet, while also increasing its precision (e= 0.14 ±0.01). Additional new spectroscopic and photometric observations allow us to estimate the rotational period of the star and to assess the potential presence of another planet.

Context.How planet properties depend on stellar mass is a key diagnostic of planetary formation mechanisms.

We present SpitzerSpaceTelescopeinfrared photometry of a primary transit of the hot Neptune GJ 436b. The observations were obtained using the 8 μm band of the InfraRed Array Camera (IRAC). The high accuracy of the transit data and the weak limb-darkening in the 8 μm IRAC band allow us to derive (assuming M= 0.44 ±0.04 $M_\odot$for the primary) a precise value for the planetary radius (4.19$^{+0.21}_{-0.16}$$R_\oplus$), the stellar radius (0.463$^{+0.022}_{-0.017}$$R_\odot$), the orbital inclination (85.90°$^{+0.19^\circ}_{-0.18^\circ}$) and transit timing (2454280.78186$^{+0.00015}_{-0.00008}$HJD). Assuming current planet models, an internal structure similar to that of Neptune with a small H/He envelope is necessary to account for the measured radius of GJ 436b.

This Letter reports on the photometric detection of transits of the Neptune-mass planet orbiting the nearby M-dwarf star GJ 436. It is by far the closest, smallest, and least massive transiting planet detected so far. Its mass is slightly larger than Neptune's at $M = 22.6 \pm 1.9~M_\oplus $. The shape and depth of the transit lightcurves show that it is crossing the host star disc near its limb (impact parameter $0.84 \pm 0.03$) and that the planet size is comparable to that of Uranus and Neptune, $R = 25\,200 \pm 2200$km = $3.95 \pm 0.35~R_\oplus$. Its main constituant is therefore very likely to be water ice. If the current planet structure models are correct, an outer layer of H/He constituting up to ten percent in mass is probably needed on top of the ice to account for the observed radius.

OGLE-TR-132b transits a very metal-rich F dwarf about 2000 pc from the Sun, in the Galactic disc towards Carina. It orbits very close to its host star ($a = 0.03$AU) and has an equilibrium temperature of nearly 2000 K. Using rapid-cadence transit photometry from the FORS2 camera on the VLT and SUSI2 on the NTT, and high-resolution spectroscopy with UVES on the VLT, we refine the shape of the transit light curve and the parameters of the system. In particular, we improve the planetary radius estimate, R= 1.18 ±0.07 RJand provide very precise ephemeris, Ttr= 2 453 142.59123 ±0.0003 BJD and P= 1.689868 ±0.000003 days. The obtained planetary mass is 1.14 ±0.12 MJ. Our results give a slightly smaller and lighter star, and bigger planet, than previous values. As the VLT/FORS2 light curve obtained in this analysis with the deconvolution photometry algorithm DECPHOT shows a transit depth in disagreement with the one obtained by a previous study using the same data, we analyze them with two other reduction methods (aperture and image subtraction). The light curves obtained with the three methods are in good agreement, though deconvolution-based photometry is significantly more precise. It appears from these results that the smaller transit depth obtained in the previous study was due to a normalisation problem inherent to the reduction procedure used.

Transiting planets are essential to study the structure and evolution of extra-solar planets. For that purpose, it is important to measure precisely the radius of these planets. Here we report new high-accuracy photometry of the transits of OGLE-TR-10 and OGLE-TR-56 with VLT/FORS1. One transit of each object was covered in Bessel Vand Rfilters, and treated with the deconvolution-based photometry algorithm DECPHOT, to ensure accurate millimagnitude light curves. Together with earlier spectroscopic measurements, the data imply a radius of $1.22\rm{^{+0.12}_{-0.07}}$RJfor OGLE-TR-10band 1.30 ±0.05 RJfor OGLE-TR-56b. A re-analysis of the original OGLE photometry resolves an earlier discrepancy about the radius of OGLE-TR-10. The transit of OGLE-TR-56 is almost grazing, so that small systematics in the photometry can cause large changes in the derived radius. Our study confirms both planets as inflated hot Jupiters, with large radii comparable to that of HD 209458band at least two other recently discovered transiting gas giants.

A new method is presented for determining the point spread function (PSF) of images that lack bright and isolated stars. It is based on the same principles as the MCS image deconvolution algorithm. It uses the information contained in all stellar images to achieve the double task of reconstructing the PSFs for single or multiple exposures of the same field and to extract the photometry of all point sources in the field of view. The use of the full information available allows us to construct an accurate PSF. The possibility to simultaneously consider several exposures makes it well suited to the measurement of the light curves of blended point sources from data that would be very difficult or even impossible to analyse with traditional PSF fitting techniques. The potential of the method for the analysis of ground-based and space-based data is tested on artificial images and illustrated by several examples, including HST/NICMOS images of a lensed quasar and VLT/ISAAC images of a faint blended Mira star in the halo of the giant elliptical galaxy NGC 5128 (Cen A).

A high accuracy photometry algorithm is needed to take full advantage of the potential of the transit method for the characterization of exoplanets, especially in deep crowded fields. It has to reduce to the lowest possible level the negative influence of systematic effects on the photometric accuracy. It should also be able to cope with a high level of crowding and with large-scale variations of the spatial resolution from one image to another. A recent deconvolution-based photometry algorithm fulfills all these requirements, and it also increases the resolution of astronomical images, which is an important advantage for the detection of blends and the discrimination of false positives in transit photometry. We made some changes to this algorithm to optimize it for transit photometry and used it to reduce NTT/SUSI2 observations of two transits of OGLE-TR-113b. This reduction has led to two very high precision transit light curves with a low level of systematic residuals, used together with former photometric and spectroscopic measurements to derive new stellar and planetary parameters in excellent agreement with previous ones, but significantly more precise.

Context.One of the main goals of the COROT mission is to get precise photometric observations of selected bright stars in order to allow the modelling of their interior through asteroseismology. However, in order to interpret the asteroseismological data, the effective temperature, surface gravity, and chemical composition of the stars must be known with sufficient accuracy.Aims.To carry out this task, we have developed a spectroscopic method called APASS (Atmospheric Parameters and Abundances from Synthetic Spectra) which allows precise analysis of stars with a moderate to high rotational velocity, which is the case for most primary COROT targets.Methods.Our method is based on synthetic spectra in which individual lines are replaced by analysis units(isolated lines or line blends, depending on the crowding of the spectral region and on the rotational broadening). It works differentially with respect to the Sun and allows the atmospheric parameters and chemical abundances to be determined by considering analysis units with different sensitivities to these various parameters.Results.Using high signal-to-noise spectra and the APASS method, we determined the atmospheric parameters and chemical abundances of 13 primary COROT targets. Our results agree well with those obtained by Bruntt using his software VWA and with those obtained with the software TEMPLOGG. However, in both cases, our error bars are significantly smaller than those of other methods. Our effective temperatures are also in excellent agreement with those obtained with the IR photometry method. For five stars with relatively low rotational velocity, we also performed an analysis with a classical equivalent–width method to test agreement with APASS results. We show that equivalent–width measurements by Gaussian or Voigt profile–fitting are sensitive to the rotational broadening, leading to systematic errors whenever the projected rotation velocity is non–negligible. The APASS method appears superior in all cases and should thus be preferred.

One of the goals of the ground-based support program for the corotand mons/rømersatellite missions is to characterize suitable target stars for the part of the missions dedicated to asteroseismology. We present the detailed abundance analysis of nine of the potential corotmain targets using the semi-automatic software vwa. For two additional corottargets we could not perform the analysis due to the high rotational velocity of these stars. For five stars with low rotational velocity we have also performed abundance analysis by a classical equivalent width method in order to test the reliability of the vwasoftware. The agreement between the different methods is good. We find that it is necessary to measure abundances extracted from each line relative to the abundances found from a spectrum of the Sun in order to remove systematic errors. We have constrained the global atmospheric parameters Teff, $\log g$, and [Fe/H] to within $70{-}100$K, $0.1{-}0.2$dex, and 0.1 dex for five stars which are slow rotators ($v\sin i < 15 {\rm km\,s}^{-1}$). For most of the stars we find good agreement with the parameters found from line depth ratios, H αlines, Strömgren indices, previous spectroscopic studies, and also $\log g$determined from the hipparcosparallaxes. For the fast rotators ($v\sin i > 60 {\rm km\,s}^{-1}$) it is not possible to constrain the atmospheric parameters.

We report the discovery of a transiting planet with an orbital period of 1.36 days orbiting the brighter component of the visual binary star BD -07 436. The host star, WASP-77 A, is a moderately bright G8 Vstar (V= 10.3) with a metallicity close to solar ([Fe/H] = 0.0 ± 0.1). The companion star, WASP-77 B, is a K-dwarf approximately 2 mag fainter at a separation of approximately 3?. The spectrum of WASP-77 A shows emission in the cores of the CaiiH and K lines, indicative of moderate chromospheric activity. The Wide Angle Search for Planets (WASP) light curves show photometric variability with a period of 15.3 days and an amplitude of about 0.3% that is probably due to the magnetic activity of the host star. We use an analysis of the combined photometric and spectroscopic data to derive the mass and radius of the planet (1.76 ± 0.06 MJup, 1.21 ± 0.02 RJup). The age of WASP-77 A estimated from its rotation rate (?1 Gyr) agrees with the age estimated in a similar way for WASP-77 B (?0.6 Gyr) but is in poor agreement with the age inferred by comparing its effective temperature and density to stellar models (?8 Gyr). Follow-up observations of WASP-77 Ab will make a useful contribution to our understanding of the influence of binarity and host star activity on the properties of hot Jupiters.

La section de l’assainissement de Paris (SAP) mène depuis 2002 l’élaboration d’un plan de protection contre les inondations destiné à lutter efficacement contre tous les risques liés à une crue de la Seine en vue de protéger ses installations et les Parisiens.Dans ce contexte, l’objet de la présente étude est d’améliorer la représentativité du modèle existant du réseau d’assainissement de Paris et de mettre en oeuvre des simulations combinées Modèle réseau (1D) – Modèle de surface (2D) pour calculer l’évolution des plans d’eau et des débits dans les principaux ouvrages parisiens pour la crue centennale de référence de la Seine. Les résultats obtenus ont permis de retrouver les limites du plan de prévention du risque d’inondation (PPRI) et les zones laissées volontairement inondables par la ville de Paris validant ainsi le modèle. D’autres simulations ont alors permis de tester divers scénarios en faisant varier les consignes de gestions des ouvrages, l’intrusion de la nappe… Cela a permis de localiser les zones de risques de résurgences des égouts sur la voie publique et donc de préconiser des actions de protection de surface à mettre en place.

From WASP photometry and SOPHIE radial velocities we report the discovery of WASP-40b (HAT-P-27b), a 0.6 MJupplanet that transits its 12th magnitude host star every 3.04 days. The host star is of late G-type or early K-type and likely has a metallicity greater than solar ([Fe/H] = 0.14 ± 0.11). The planet's mass and radius are typical of the known hot Jupiters, thus adding another system to the apparent pileup of transiting planets with periods near 3-4 days. Our parameters match those of the recent HATnet announcement of the same planet, thus giving confidence in the techniques used. We report a possible indication of stellar activity in the host star.

We report the discovery of a transiting planet with an orbital period of 3.05 days orbiting the star TYC 7247-587-1. The star, WASP-41, is a moderately bright G8 Vstar (V= 11.6) with a metallicity close to solar ([Fe/H] = -0.08 ± 0.09). The star shows evidence of moderate chromospheric activity, both from emission in the cores of the Ca iiH and K ines and photometric variability with a period of 18.4 days and an amplitude of about 1%. We use a new method to show quantitatively that this periodic signal has a low false-alarm probability. The rotation period of the star implies a gyrochronological age for WASP-41 of 1.8 Gyr with an error of about 15%. We have used a combined analysis of the available photometric and spectroscopic data to derive the mass and radius of the planet (0.92 ± 0.06 MJup, 1.20 ± 0.06 RJup). Further observations of WASP-41 can be used to explore the connections between the properties of hot Jupiter planets and the level of chromospheric activity in their host stars.

We report the discovery of a transiting planet orbiting the star TYC 2-1155-1. The star, WASP-32, is a moderately bright (V= 11.3) solar-type star (Teff= 6100 ± 100 K, [Fe/H] = -0.13 ± 0.10). The light curve of the star obtained with the WASP-South and WASP-North instruments shows periodic transitlike features with a depth of about 1% and a duration of 0.10 day every 2.72 days. The presence of a transitlike feature in the light curve is confirmed using z-band photometry obtained with Faulkes Telescope North. High-resolution spectroscopy obtained with the Coralie spectrograph confirms the presence of a planetary mass companion. From a combined analysis of the spectroscopic and photometric data, assuming that the star is a typical main-sequence star, we estimate that the planet has a mass Mpof 3.60 ± 0.07 MJupand a radius Rp= 1.19 ± 0.06 RJup. WASP-32 is one of a small group of hot Jupiters with masses greater than 3 MJup. We find that some stars with hot Jupiter companions and with masses M?? 1.2 M?, including WASP-32, are depleted in lithium and that the majority of these stars have lithium abundances similar to field stars.

We report on an intensive observational campaign carried out with HARPS at the 3.6?m telescope at La Silla on the star CoRoT-7. Additional simultaneous photometric measurements carried out with the Euler Swiss telescope have demonstrated that the observed radial velocity variations are dominated by rotational modulation from cool spots on the stellar surface. Several approaches were used to extract the radial velocity signal of the planet(s) from the stellar activity signal. First, a simple pre-whitening procedure was employed to find and subsequently remove periodic signals from the complex frequency structure of the radial velocity data. The dominant frequency in the power spectrum was found at 23??days, which corresponds to the rotation period of CoRoT-7. The 0.8535?day period of CoRoT-7b?planetary candidate was detected with an amplitude of 3.3?m?s-1. Most other frequencies, some with amplitudes larger than the CoRoT-7b signal, are most likely associated with activity. A second approach used harmonic decomposition of the rotational period and up to the first three harmonics to filter out the activity signal from radial velocity variations caused by orbiting planets. After correcting the radial velocity data for activity, two periodic signals are detected: the CoRoT-7b? transit period and a second one with a period of 3.69?days and an amplitude of 4?m?s-1. This second signal was also found in the pre-whitening analysis. We attribute the second signal to a second, more remote planet CoRoT-7c?. The orbital solution of both planets is compatible with circular orbits. The mass of CoRoT-7b?is 4.8?0.8 (M) and that of CoRoT-7c?is 8.4?0.9 (M), assuming both planets are on coplanar orbits. We also investigated the false positive scenario of a blend by a faint stellar binary, and this may be rejected by the stability of the bisector on a nightly scale. According to their masses both planets belong to the super-Earth planet category. The average density of CoRoT-7b?is ?=5.6?1.3gcm-3, similar to the Earth. The CoRoT-7?planetary system provides us with the first insight into the physical nature of short period super-Earth planets recently detected by radial velocity surveys. These planets may be denser than Neptune and therefore likely made of rocks like the Earth, or a mix of water ice and rocks.

The gaseous giant planets WASP-4b and WASP-5b are transiting 12-magnitude solar-type stars in the Southern hemisphere. The aim of the present work is to refine the parameters of these systems using high cadence VLT/FORS2 z-band transit photometry and high-resolution VLT/UVES spectroscopy. For WASP-4, the new estimates for the planet radius and mass from a combined analysis of our VLT?data with previously published transit photometry and radial velocities are Rp= 1.30+0.05-0.04?RJand Mp= 1.21+0.13-0.08?MJ, resulting in a density ?p= 0.55+0.04-0.02??J. The radius and mass for the host star are R*= 0.87+0.04-0.03?R?and M*= 0.85+0.11-0.07?M?. Our ground-based photometry reaches 550?ppm at time sampling of ~50?s. Nevertheless, we also report the presence of an instrumental effect on the VLT that degraded our photometry for the WASP-5 observations. This effect could be a major problem for similar programs. Our new estimates for the parameters of the WASP-5 system are Rp= 1.09?? 0.07?RJ, Mp= 1.58+0.13-0.10?MJ, ?p= 1.23 +0.26-0.16??J, R*= 1.03+0.06-0.07?R?, and M*= 0.96+0.13-0.09?M?. The measured size of WASP-5b agrees well with the basic models of irradiated planets, while WASP-4b is clearly an ?anomalously? large planet.

A 10.24-day Neptune-mass planet was recently announced as orbiting the nearby M2 dwarf Gl?176, based on 28?radial velocities measured with the HRS?spectrograph on the Hobby-Heberly Telescope. We obtained 57?radial velocities of Gl?176 with the ESO?3.6?m telescope and the HARPS spectrograph, which is known for its sub-m?s-1stability. The median photon-noise standard error of our measurements is 1.1?m?s-1, significantly lower than the 4.7?m?s-1of the HET?velocities, and the 4-year period over which they were obtained overlaps considerably with the epochs of the HET?measurements. The HARPS?measurements show no evidence of a signal at the period of the putative HET?planet, suggesting that its detection was spurious. We do find, on the other hand, strong evidence of a lower mass 8.4?MEarthplanet, in a quasi-circular orbit and at the different period of 8.78?days. The host star has moderate magnetic activity and rotates on a 39-day period, which we confirm through modulation of both contemporaneous photometry and chromospheric indices. We detect that period, as well, in the radial velocities, but it is well removed from the orbital period and offers no cause for confusion. This new detection of a super-Earth (2?MEarth?

We report the discovery of WASP-6b, an inflated sub-Jupiter mass planet transiting every 3.3610060+ 0.0000022 - 0.0000035 ?days a mildly metal-poor solar-type star of magnitude V = 11.9. A combined analysis of the WASP photometry, high-precision followup transit photometry and radial velocities yield a planetary mass Mp= 0.503+0.019-0.038MJand radius Rp= 1.224+0.051-0.052RJ, resulting in a density ?p= 0.27 ?0.05 ?J. The mass and radius for the host star are M*= 0.88+0.05-0.08M?and R*= 0.870+0.025-0.036R?. The non-zero orbital eccentricity e = 0.054+0.018-0.015that we measure suggests that the planet underwent a massive tidal heating ~1?Gyr ago that could have contributed to its inflated radius. High-precision radial velocities obtained during a transit allow us to measure a sky-projected angle between the stellar spin and orbital axis ?= 11+14-18?deg. In addition to similar published measurements, this result favors a dominant migration mechanism based on tidal interactions with a protoplanetary disk.

We present observations of two new single-lined eclipsing binaries, both consisting of an Am star and an M-dwarf, discovered by the Wide Angle Search for Planets transit photometry survey. Using WASP photometry and spectroscopic measurements we find that HD?186753B has an orbital period of P=1.9194 days, a mass of M=0.24?0.02?M?and radius of R=0.31+0.06-0.06?R?; and that TCY7096-222-1B has an orbital period of P=8.9582 days, a mass of between 0.29 and 0.54?M?depending on eccentricity and radius of R=0.263+0.02-0.07?R?. We find that the Am stars have relatively low rotational velocities that closely match the orbital velocities of the M-dwarfs, suggesting that they have been ?spun-down? by the M-dwarfs.

Context. TW?Hya is a classical T Tauri star that shows significant radial-velocity variations in the optical regime. These variations have been attributed to a 10?MJup planet orbiting the star at 0.04?AU. Aims. The aim of this letter is to confirm the presence of the giant planet around TW?Hya by (i) testing whether the observed RV?variations can be caused by stellar spots and (ii) analyzing new optical and infrared data to detect the signal of the planet companion. Methods. We fitted the RV?variations of TW?Hya using a cool spot model. In addition, we obtained new high-resolution optical & infrared spectra, together with optical photometry of TW?Hya and compared them with previous data. Results. Our model shows that a cold spot covering 7% of the stellar surface and located at a latitude of 54? can reproduce the reported RV?variations. The model also predicts a bisector semi-amplitude variation <10?m?s-1, which is less than the errors of the RV?measurements discussed in Setiawan et?al. (2008, Nature, 451, 38). The analysis of our new optical RV?data, with typical errors of?10?m?s-1, shows a larger RV?amplitude that varies depending on the correlation mask used. A slight correlation between the RV?variation and the bisector is also observed although not at a very significant level. The infrared H-band RV?curve is almost flat, showing a small variation (<35?m?s-1) that is not consistent with the published optical orbit. All these results support the spot scenario rather than the presence of a hot Jupiter. Finally, the photometric data shows a 20% (peak to peak) variability, which is much larger than the 4% variation expected for the modeled cool spot. The fact that the optical data are correlated with the surface of the cross-correlation function points towards hot spots as being responsible for the photometric variability. Conclusions. We conclude that the best explanation for the RV?signal observed in TW?Hya is the presence of a cool stellar spot and not an orbiting hot Jupiter.

We present results of the photometric campaign for planetary and low-luminosity object transits conducted by the OGLE survey in the 2005 season (Campaign #5). About twenty of the most promising candidates discovered in these data were subsequently verified spectroscopically with the VLT/FLAMES spectrograph. One of the candidates, OGLE-TR-211, reveals clear changes of radial velocity with a small amplitude of 82?m/s, varying in phase with photometric transit ephemeris. Further analysis confirms the planetary nature of this system. Follow-up precise photometry of OGLE-TR-211 with VLT/FORS, together with radial velocity spectroscopy, supplemented with high-resolution, high S/N VLT/UVES spectra allowed us to derive parameters of the planet and host star. OGLE-TR-211b is a hot Jupiter orbiting an F7-8 spectral type dwarf star with a period of 3.68?days. The mass of the planet is equal to 1.03?0.20 MJup, while its radius 1.36+0.18-0.09RJup. The radius is about 20% larger than the typical radius of hot Jupiters of similar mass. OGLE-TR-211b is, then, another example of inflated hot Jupiters ? a small group of seven exoplanets with large radii and unusually low densities ? objects that are a challenge to the current models of exoplanets.

1. Left or right cervical vagotomy caused elevated intakes of water after hypertonic saline, isoprenaline and polyethylene glycol compared with normal rats. In cervically vagotomized rats sodium nitrite caused a dose‐dependent water intake whereas in normal rats it produced a smaller, more variable response. The same procedure also reduced the extent to which drinking following overnight water deprivation was inhibited by plasma volume expansion. Drinking after diazoxide or in response to ligation of the abdominal inferior vena cava was not affected by cervical vagotomy. 2. The antidiuresis that followed isoprenaline treatment was greater in cervically vagotomized than normal rats; that which occurred after caval ligation was unaffected. 3. Subdiaphragmatic vagotomy did not alter water intake in response to hypertonic saline, isoprenaline or polyethylene glycol. 4. It is concluded that nerves within the supradiaphragmatic distribution of the vagi modify water intake in response to changes in the degree of vascular filling.

1. In order to investigate the mechanisms of hypovolaemic thirst and sodium appetite an inflatable balloon in the upper abdominal inferior vena cava was used to produce acute, graded and reversible reductions in venous return to the heart in conscious dogs. 2. Reducing venous return caused a fall in central venous, arterial and pulse pressures. Heart rate and venous pressure upstream from the point of inflation rose. 3. Within 6‐‐28 min of inflating the balloon the dogs started drinking. The amount drunk in a 1 h experiment was significantly correlated with the changes in central venous and arterial pressures. 4. More prolonged obstruction to venous return led to a sustained increase in water intake and the development of a sodium appetite. 5. Plasma renin activity and concentration rose following caval obstruction. 6. Drinking in response to reductions in venous return was reduced, but not abolished, by simultaneous infusion of the competitive angiotensin II antagonist saralasin acetate. 7. When the left vagosympathetic nerve was blocked at the same time as balloon inflation the response was enhanced. 8. Urine flow fell after partial obstruction of the vena cava. Therefore drinking led to the development of a positive fluid balance. 9. We have shown that hypovolaemia is a potent and quantitatively defined stimulus to drinking in the dog and that the renal renin‐angiotensin system makes an important contribution to it.

1. Inflation of a balloon implanted in the abdominal aorta above the level of the renal arteries was used to produce partial obstruction to aortic blood flow in trained, conscious mongrel dogs.

Background and objectives: Citrate reactions are uncomfortable and potentially dangerous to apheresis donors. Reduction of citrate increases comfort, but may lead to platelet clumping. Materials and methods: We describe a protocol for stepwise reduction of the volume of ACD-A injected during plateletpheresis. This protocol has been carried out in 45 healthy donors with the Cobe 2997 (Cobe) cell separator, and in 35 with the Fenwal-CS 3000 (CS). Results: Using this protocol, during the first hour of platelet collection, ionised calcium decreased on average by 18% for CS and by 18.4% for Cobe. During the second hour, Ca²⁺ and citrate ion concentration did not change with either Cobe or CS (about 65% of citrate ion load is eliminated). We observed mild signs of neuromuscular hyperexcitability in only 22% and 28% of donors with Cobe and CS, respectively. We also found a significant reduction of phosphate ions (p &lt; 0.0001) at the end of the procedures. Conclusions: With this stepdown citrate reduction protocol, we obtained a significant reduction of injected citrate without the complication of platelet clumps.

Because of its anatomy, the liver can be divided into two hemilivers suitable for use as two grafts for liver transplantation. The line of division is the main scissure, giving the right hemiliver (segments 5–8) and the left hemiliver (segments 2–4). Segment 1 (caudate lobe) has to be resected. The vessels are divided between the two grafts: the vena cava remains on the right; on the left, the left hepatic vein is sutured into the vena cava of the recipient, which is retained intact. The left graft retains only the left branch of the portal vein, the bile duct and the hepatic artery. The right graft retains the portal trunk, the common bile duct and the right branch of the hepatic artery. This procedure was used for emergency grafting of two patients with fulminant hepatitis when only one donor was available. Both recipients recovered from coma and regained normal liver function. However, both died from causes not specifically related to the operative technique, one from multiple organ failure on the 20th day and the other from diffuse cytomegalovirus infection on the 45th day.

We announce the discovery of the transiting hot Jupiter WASP-157b in a 3.95-d orbit around a V= 12.9 G2 main-sequence star. This moderately inflated planet has a Saturn-like density, with a mass of 0.57 ± 0.10 MJupand a radius of 1.06 ± 0.05 RJup. We do not detect any rotational or phase curve modulations, nor the secondary eclipse, with conservative semi-amplitude upper limits of 250 and 20 ppm, respectively.

We present the discovery by the WASP-South survey of three planets transiting moderately bright stars (V ? 11). WASP-120 b is a massive (4.85 MJup) planet in a 3.6-day orbit that we find likely to be eccentric () around an F5 star. WASP-122 b is a hot Jupiter (1.28 MJup, 1.74 RJup) in a 1.7-day orbit about a G4 star. Our predicted transit depth variation caused by the atmosphere of WASP-122 b suggests it is well suited to characterization. WASP-123 b is a hot Jupiter (0.90 MJup, 1.32 RJup) in a 3.0-day orbit around an old (?7 Gyr) G5 star.