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.

Aims. In the framework of the search for extrasolar planets and brown dwarfs around early-type main-sequence stars, we present the results obtained on the early F-type star θCygni.

We report on the discovery of a substellar companion or a massive Jupiter orbiting the G5V star HD 16760 using the spectrograph SOPHIEinstalled on the OHP 1.93-m telescope. Characteristics and performances of the spectrograph are presented, as well as the SOPHIEexoplanet consortium program. With a minimum mass of 14.3 ${M}_{\rm Jup}$, an orbital period of 465 days and an eccentricity of 0.067, HD 16760b seems to be located just at the end of the mass distribution of giant planets, close to the planet/brown-dwarf transition. Its quite circular orbit supports a formation in a gaseous protoplanetary disk.

We measured the radii of 7 low and very low-mass stars using long baseline interferometry with the VLTI interferometer and its VINCI and AMBER near-infrared recombiners. We use these new data, together with literature measurements, to examine the luminosity-radius and mass-radius relations for K and M dwarfs. The precision of the new interferometric radii now competes with what can be obtained for double-lined eclipsing binaries. Interferometry provides access to much less active stars, as well as to stars with much better measured distances and luminosities, and therefore complements the information obtained from eclipsing systems. The radii of magnetically quiet late-K to M dwarfs match the predictions of stellar evolution models very well, providing direct confirmation that magnetic activity explains the discrepancy that was recently found for magnetically active eclipsing systems. The radii of the early K dwarfs are reproduced well for a mixing length parameter that approaches the solar value, as qualitatively expected.

We recently reported the photometric and spectroscopic detection of the primary transit of the 111-day-period, eccentric extra-solar planet HD 80606b, at Observatoire de Haute-Provence, France. The whole egress of the primary transit and a section of its central part were observed, allowing the measurement of the planetary radius, and evidence for a spin-orbit misalignment through the observation of the Rossiter-McLaughlin anomaly. The ingress not having been observed for this long-duration transit, uncertainties remained in the parameters of the system. We present here a refined, combined analysis of our photometric and spectroscopic data, together with further published radial velocities, ground-based photometry, and Spitzerphotometry around the secondary eclipse, as well as new photometric measurements of HD 80606 acquired at Mount Hopkins, Arizona, just before the beginning of the primary transit. Although the transit is not detected in those new data, they provide an upper limit for the transit duration, which narrows down the possible behaviour of the Rossiter-McLaughlin anomaly in the unobserved part of the transit. We analyse the whole data with a Bayesian approach using a Markov-chain Monte Carlo integration on all available information. We find $R_{\rm p} = 0.98 \pm 0.03 \,{R}_{\rm Jup}$for the planetary radius, and a total primary transit duration of $11.9 \pm 1.3$h from first to fourth contact. Our analysis reinforces the hypothesis of spin-orbit misalignment in this system (alignment excluded at >95% level), with a positive projected angle between the planetary orbital axis and the stellar rotation (median solution $\lambda \sim 50^\circ$). As HD 80606 is a component of a binary system, the peculiar orbit of its planet could result from a Kozai mechanism.

We report the detection of the primary transit of the extra-solar planet HD 80 606 b, thanks to photometric and spectroscopic observations performed at the Observatoire de Haute-Provence, simultaneously with the CCD camera at the 120-cm telescope and the SOPHIEspectrograph on the 193-cm telescope. We observed the whole egress of the transit and partially its central part, in both datasets with the same timings. The ingress occurred before sunset so was not observed. The full duration of the transit was between 9.5 and 17.2 h. The data allows the planetary radius to be measured ($R_{\mathrm{p}} = 0.9 \pm 0.10\,{R}_{\rm Jup}$) and other parameters of the system to be refined. Radial velocity measurements show the detection of a prograde Rossiter-McLaughlin effect, and provide a hint of a spin-orbit misalignment. If confirmed, this misalignment would corroborate the hypothesis that HD 80 606 b owes its unusual orbital configuration to Kozai migration. HD 80 606 b is by far the transiting planet on the longest period detected today. Its unusually small radius reinforces the observed relationship between the planet radius and the incident flux received from the star and opens new questions for theory. Orbiting a bright star ($V=9$), it opens opportunities for numerous follow-up studies.

Aims. Extra-solar planet search programs require high-precision velocity measurements. They need to determine how to differentiate between radial-velocity variations due to Doppler motion and the noise induced by stellar activity.

The transiting extrasolar planet XO-3b is remarkable, with a high mass and eccentric orbit. These unusual characteristics make it interesting to test whether its orbital plane is parallel to the equator of its host star, as it is observed for other transiting planets. We performed radial velocity measurements of XO-3 with the SOPHIEspectrograph at the 1.93 m telescope of Haute-Provence Observatory during a planetary transit and at other orbital phases. This allowed us to observe the Rossiter-McLaughlin effect and, together with a new analysis of the transit light curve, to refine the parameters of the planet. The unusual shape of the radial velocity anomaly during the transit provides a hint of a nearly transverse Rossiter-McLaughlin effect. The sky-projected angle between the planetary orbital axis and the stellar rotation axis should be λ= 70° ±15° to be compatible with our observations. This suggests that some close-in planets might result from gravitational interaction between planets and/or stars rather than migration due to interaction with the accretion disk. This surprising result requires confirmation by additional observations, especially at lower airmass, to fully exclude the possibility that the signal is due to systematic effects.

We present the detection of a 0.47 $M_{{\rm Jup}}$planet in a 44-day period eccentric trajectory (e= 0.39) orbiting the metal-rich star HD 45652. This planet, the seventh giant planet discovered in the context of the ELODIE metallicity-biased planet search program, is also confirmed using higher precision radial-velocities obtained with the CORALIE and SOPHIE spectrographs. The orbital period of HD 45652b places it in the middle of the “gap” in the period distribution of extra-solar planets.

We report the detection of two very eccentric planets orbiting HD 4113and HD 156846with the CORALIE Echelle spectrograph mounted on the 1.2-m Euler Swiss telescope at La Silla. The first planet, HD 4113b, has minimum mass of $m\sin{i}=1.6$±$0.2~M_{\rm Jup}$, a period of $P=526.59$±0.21 days and an eccentricity of $e=0.903$±0.02. It orbits a metal rich G5V star at $a=1.28$AU, which displays an additional radial velocity drift of 28 m s-1yr-1observed during 8 years. The combination of the radial-velocity data and the non-detection of any main sequence stellar companion in our high contrast images, taken at the VLT with NACO/SDI, characterizes the companion as a probable brown dwarf or as a faint white dwarf. The second planet, HD 156846 b, has minimum mass of $m\sin{i}=10.45$±$0.05~M_{\rm Jup}$, a period of $P=359.51$±0.09 days, an eccentricity of $e=0.847$±0.002 and is located at $a=1.0$AU from its parent star. HD 156846is a metal rich G0 dwarf and is also the primary of a wide binary system ($a>250$AU, $P>4000$years). Its stellar companion, IDS 17147-1914 B, is a M4 dwarf. The very high eccentricities of both planets can be explained by Kozai oscillations induced by the presence of a third object.

Context.Although it is commonly agreed that the presence of a close stellar companion is likely to affect planet formation and evolution, the precise effects and their actual impact on planet occurrence are still debated. Different conclusions have been reached on the theoretical side, while observational constraints are sparse, a consequence of the discrimination against close binaries in Doppler planet searches. Accordingly, basic questions such as how hospitable binaries are to planets and how binary separation and mass ratio impact on planet formation, remain poorly known.

We report here the discovery of two planet candidates as a result of our planet-search programme biased in favour of high-metallicity stars, using the ELODIE spectrograph at the Observatoire de Haute Provence. One candidate has a minimum mass $m_2\sin{i} = 2.5$MJupand is orbiting the metal-rich star HD 43691with period $P = 40$days and eccentricity $e=0.14$. The other planet has a minimum mass $m_2\sin{i} = 5.6$MJupand orbits the slightly metal-rich star HD 132406with period $P=974$days and eccentricity e= 0.34. Additional observations for both stars were performed using the new SOPHIE spectrograph that replaces the ELODIE instrument, allowing an improved orbital solution for the systems.

Context.Because of the lack of precise masses, the coverage of the main-sequence empirical mass-luminosity relation for stars in the mass range from 0.6 $\mathcal{M}_{\odot}$to 0.9 $\mathcal{M}_{\odot}$is incomplete. The nearby K-type visual and spectroscopic binary GJ 765.2 = MLR 224 is a good candidate for new reliable points in this significant part of the relation.

We report the discovery of companions to 5 nearby late M dwarfs (>M5), LHS1901, LHS4009, LHS6167, LP869-26 and WT460, and we confirm that the recently discovered mid-T brown dwarf companion to SCR1845-6357 is physically bound to that star. These discoveries result from our adaptive optics survey of all M dwarfs within 12 pc. The new companions have spectral types M5 to L1, and orbital separations between 1 and 10 AU. They add significantly to the number of late M dwarfs binaries in the immediate solar neighbourhood, and will improve the multiplicity statistics of late M dwarfs. The expected periods range from 3 to 130 years. Several pairs thus have good potential for accurate mass determination in this poorly sampled mass range.

We report the discovery of a new planet candidate orbiting the subgiant star HD 118203with a period of P= 6.1335 days. The best Keplerian solution yields an eccentricity e= 0.31 and a minimum mass $m_2\sin{i}$= 2.1 MJupfor the planet. This star has been observed with the ELODIE fiber-fed spectrograph as one of the targets in our planet-search programme biased toward high-metallicity stars, on-going since March 2004 at the Haute-Provence Observatory. An analysis of the spectroscopic line profiles using line bisectors revealed no correlation between the radial velocities and the line-bisector orientations, indicating that the periodic radial-velocity signal is best explained by the presence of a planet-mass companion. A linear trend is observed in the residuals around the orbital solution that could be explained by the presence of a second companion in a longer-period orbit. We also present here our orbital solution for another slightly evolved star in our metal-richsample, HD 149143, recently proposed to host a 4-d period Hot Jupiter by the N2K consortium. Our solution yields a period P= 4.09 days, a marginally significant eccentricity e= 0.08 and a planetary minimum mass of 1.36 MJup. We checked that the shape of the spectral lines does not vary for this star as well.

For the nearby dwarf star αCen B (K1 V), we present limb-darkening predictions from a 3D hydrodynamical radiative transfer model of its atmosphere. We first compared the results of this model to a standard Kurucz's atmosphere. Then we used both predictions to fit the new interferometric visibility measurements of αCen B obtained with the VINCI instrument of the VLT Interferometer. Part of these new visibility measurements were obtained in the second lobe of the visibility function, which is sensitive to stellar limb-darkening. The best agreement is found for the 3D atmosphere limb-darkening model and a limb-darkened angular diameter of $\theta_{\rm 3D} = 6.000\pm 0.021$mas, corresponding to a linear radius of $0.863 \pm 0.003\,R_\odot$(assuming $\pi = 747.1 \pm 1.2$mas). Our new linear radius agrees well with the asteroseismic value predicted by Thévenin et al. (2002, A&A, 392, L9). In view of future observations of this star with the VLTI/AMBER instrument, we also present limb-darkening predictions in the J, H, and Kbands.

We report the discovery of three new planets, detected through Doppler measurements with the instrument harpsinstalled on the ESO 3.6 m telescope, La Silla, Chile. These planets are orbiting the main-sequence stars HD 2638, HD 27894, and HD 63454. The orbital characteristics that best fit the observed data are depicted in this paper, as well as the stellar and planetary parameters. The planets' minimum mass is 0.48, 0.62, and 0.38 $M_{\mathrm{Jup}}$for respectively HD 2638, HD 27894, and HD 63454; the orbital periods are 3.4442, 17.991, and 2.817822 days, corresponding to semi-major axis of 0.044, 0.122, and 0.036 AU, respectively. The observational data are carefully analysed for activity-induced effects and we conclude on the reliability of the observed radial-velocity variations as of exoplanetary origin. These three planets support the correlation between the star metallicity and the presence of planets (especially at short orbital distances), pointing towards the peculiar scenario of formation and migration of hot Jupiters.

We present the discovery of a tight M8V binary, with a separation of only 1.2 astronomical units, obtained with the PUEO and NACO adaptive optics systems, respectively at the CFHT and VLT telescopes. The estimated period of LP 349-25 is approximately 5 years, and this makes it an excellent candidate for a precise mass measurement.

We report in this paper the direct interferometric measurement of the angular diameter of five nearby Vega-like stars: αPsA, βLeo, βPic, ϵEri and τCet. The near-infrared (Kand Hbands) observations were conducted at the VLTI during the commissioning period with the VINCI instrument and three different baselines ranging from 66 m to 140 m. The five stellar photospheres are resolved and we derive their angular diameters with a 1 to 2% accuracy, except for βPic (14%). We discuss the detectability and the influence of a possible small amount of warm circumstellar dust on our measurements. In addition, we have used the stellar evolution code CESAM (Morel [CITE]) to compare the computed fundamental parameters to the observed values (linear diameter, luminosity, temperature and chemical abundance). As a result of the simulation, the age of the stars is inferred and found to be in good agreement with previous estimates from various other methods.

We present the discovery of an L0 companion to the nearby M1.5 dwarf G 239-25, at a projected distance of 31 AU. It is the faintest companion discovered so far in our adaptive optics survey of all known M dwarfs within 12 pc, and it lies at the stellar/substellar limit. Given the assumed age of the primary star, the companion is likely an extremely low mass star. The long orbital period of G 239-25 AB (≈100 years) precludes a direct mass determination, but the relatively wide angular separation will allow detailed analyses of its near infrared and visible spectra.

The availability of a number of new interferometric measurements of Main Sequence and subgiant stars makes it possible to calibrate the surface brightness relations of these stars using exclusively direct angular diameter measurements. These empirical laws make it possible to predict the limb darkened angular diameters $\theta_{\rm LD}$of dwarfs and subgiants using their dereddened Johnson magnitudes, or their effective temperature. The smallest intrinsic dispersions of $\sigma \le 1\%$in $\theta_{\rm LD}$are obtained for the relations based on the Kand Lmagnitudes, for instance $\log \theta_{\rm LD} = 0.0502\,(B-L) + 0.5133 - 0.2\,L$or $\log \theta_{\rm LD} = 0.0755\,(V-K) + 0.5170 - 0.2\rm \,K$. Our calibrations are valid between the spectral types A0 and M2 for dwarf stars (with a possible extension to later types when using the effective temperature), and between A0 and K0 for subgiants. Such relations are particularly useful for estimating the angular sizes of calibrators for long-baseline interferometry from readily available broadband photometry.

We present some results of a CFHT adaptive optics search for companions to nearby dwarfs. We identify 21 new components in solar neighbourhood systems, of which 13 were found while surveying a volume-limited sample of M dwarfs within 12 pc. We are obtaining complete observations for this subsample, to derive unbiased multiplicity statistics for the very-low-mass disk population. Additionally, we resolve for the first time 6 known spectroscopic or astrometric binaries, for a total of 27 newly resolved companions. A significant fraction of the new binaries has favourable parameters for accurate mass determinations. The newly resolved companion of Gl 120.1C was thought to have a spectroscopic minimum mass in the brown-dwarf range (Duquennoy & Mayor [CITE]), and it contributed to the statistical evidence that a few percent of solar-type stars might have close-in brown-dwarf companions. We find that Gl 120.1C actually is an unrecognised double-lined spectroscopic pair. Its radial-velocity amplitude had therefore been strongly underestimated by Duquennoy & Mayor ([CITE]), and it does not truly belong to their sample of single-lined systems with minimum spectroscopic mass below the substellar limit. 
We also present the first direct detection of Gl 494B, an astrometric brown-dwarf candidate. Its luminosity straddles the substellar limit, and it is a brown dwarf if its age is less than ~300 Myr. A few more years of observations will ascertain its mass and status from first principles.

The interferometric data processing methods that we describe in this paper use a number of innovative techniques. In particular, the implementation of the wavelet transform allows us to obtain a good immunity of the fringe processing to false detections and large amplitude perturbations by the atmospheric piston effect, through a careful, automated selection of the interferograms. To demonstrate the data reduction procedure, we describe the processing and calibration of a sample of stellar data from the VINCI beam combiner. Starting from the raw data, we derive the angular diameter of the dwarf star αCen A. Although these methods have been developed specifically for VINCI, they are easily applicable to other single-mode beam combiners, and to spectrally dispersed fringes.

We compare the first direct angular diameter measurements obtained on our closest stellar neighbour, αCentauri, to recent model diameters constrained by asteroseismic observations. Using the VINCI instrument installed at ESO's VLT Interferometer (VLTI), the angular diameters of the two main components of the system, αCen A and B, were measured with a relative precision of 0.2% and 0.6% respectively. Particular care has been taken in the calibration of these measurements, considering that VINCI is estimating the fringe visibility using a broadband K filter. We obtain uniform disk angular diameters for αCen A and B of $\rm \theta_{\rm UD}[A] = 8.314 \pm 0.016$mas and $\rm \theta_{\rm UD}[B] = 5.856 \pm 0.027$mas, and limb darkened angular diameters of $\rm \theta_{\rm LD}[A] = 8.511 \pm 0.020$mas and $\rm \theta_{\rm LD}[B] = 6.001 \pm 0.034$mas. Combining these values with the parallax from Söderhjelm (1999), we derive linear diameters of $D[{\rm A}] = 1.224 \pm 0.003\ D_{\odot}$and $D[{\rm B}] = 0.863 \pm 0.005\ D_{\odot}$. These values are compatible with the masses published by Thévenin et al. (2002) for both stars.

We present 4 very low mass stars radii measured with the VLTI using the 2.2 μm VINCI test instrument. The observations were carried out during the commissioning of the 104-meter-baseline with two 8-meter-telescopes. We measure angular diameters of 0.7–1.5 mas with accuracies of 0.04–0.11 mas, and for spectral type ranging from M0V to M5.5V. We determine an empirical mass-radius relation for M dwarfs based on all available radius measurements. The observed relation agrees well with theoretical models at the present accuracy level, with possible discrepancy around 0.5–0.8 $M_{\odot}$that needs to be confirmed. In the near future, dozens of M dwarfs radii will be measured with 0.1–1% accuracy, with the VLTI, thanks to the improvements expected from the near infrared instrument AMBER. This will bring strong observational constraints on both atmosphere and interior physics.

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.

We present new results of a search for extrasolar planets. The survey uses radial-velocity techniques and focuses on metal-rich stars. We used radial velocity measurements obtained with the echelle spectrograph ELODIE at the Observatoire de Haute Provence. New data have revealed a planetary companion to the slightly evolved star HD 185269. It belongs to the hot Jupiter class of planets, with a projected mass $M\sin\,i=1.0$MJupand period $P=6.84$days. We describe the measurements that led to this discovery and discuss the orbital solution.

A rich population of low‐mass planets orbiting solar‐type stars on tight orbits has been detected by Doppler spectroscopy. These planets have masses in the domain of super‐Earths and Neptune‐type objects, and periods less than 100 days. In numerous cases these planets are part of very compact multiplanetary systems. Up to seven planets have been discovered orbiting one single star. These low‐mass planets have been detected by the HARPS spectrograph around 30 % of solar‐type stars. This very high occurrence rate has been recently confirmed by the results of the Kepler planetary transit space mission. The large number of planets of this kind allows us to attempt a first characterization of their statistical properties, which in turn represent constraints to understand the formation process of these systems. The achieved progress in the sensitivity and stability of spectrographs have already led to the discovery of planets with masses as small as 1.5 M⊕(© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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 present results obtained with different adaptive optics systems (ADONIS, PUEO, NAOS), in either imaging or coronagraphic modes, in the frame of several surveys aimed at searching for very low mass stars and substellar objects around nearby M dwarfs as well as in young closeby associations. For the M dwarfs of the solar neighborhood, we have obtained a very accurate mass-luminosity relation that we can compare to the prediction of recent stellar structure models. We also present multiplicity statistics of M dwarfs (binary fraction, period and mass ratio distribution), which are crucial constraints for stellar formation scenarii. We also discuss results obtained on two young closeby associations, MBM12 and Tucana-Horologium.

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.

We present the discovery of four new long-period planets within the HARPS high-precision sample: HD 137388b (Msini= 0.22 MJ), HD 204941b (Msini= 0.27 MJ), HD 7199b (Msini= 0.29 MJ), HD 7449b (Msini= 1.04 MJ). A long-period companion, probably a second planet, is also found orbiting HD 7449. Planets around HD 137388, HD 204941, and HD 7199 have rather low eccentricities (less than 0.4) relative to the 0.82 eccentricity of HD 7449b. All these planets were discovered even though their hosting stars have clear signs of activity. Solar-like magnetic cycles, characterized by long-term activity variations, can be seen for HD 137388, HD 204941 and HD 7199, whereas the measurements of HD 7449 reveal a short-term activity variation, most probably induced by magnetic features on the stellar surface. We confirm that magnetic cycles induce a long-term radial velocity variation and propose a method to reduce considerably the associated noise. The procedure consists of fitting the activity index and applying the same solution to the radial velocities because a linear correlation between the activity index and the radial velocity is found. Tested on HD 137388, HD 204941, and HD 7199, this correction reduces considerably the stellar noise induced by magnetic cycles and allows us to derive precisely the orbital parameters of planetary companions.

We report the discovery of WASP-43b, a hot Jupiter transiting a K7V star every 0.81 d. At 0.6-M⊙the host star has the lowest mass of any star currently known to host a hot Jupiter. It also shows a 15.6-d rotation period. The planet has a mass of 1.8 MJup, a radius of 0.9 RJup, and with a semi-major axis of only 0.014 AU has the smallest orbital distance of any known hot Jupiter. The discovery of such a planet around a K7V star shows that planets with apparently short remaining lifetimes owing to tidal decay of the orbit are also found around stars with deep convection zones.

We report the detection of four new extrasolar planets in orbit around the moderately active stars HD 63765, HD 104067, HIP 70849, and HD 125595with the HARPS Echelle spectrograph mounted on the ESO 3.6-m telescope at La Silla. The first planet, HD 63765b, has a minimum mass of 0.64 MJup, a period of 358 days, and an eccentricity of 0.24. It orbits a G9 dwarf at 0.94 AU. The second planet, HD 104067b, is a 3.6 Neptune-mass-planet with a 55.8-day-period. It orbits its parent K2 dwarf, in a circular orbit with a semi-major axis of a= 0.26 AU. Radial velocity measurements present a  ≈ 500-day-oscillation that reveals significant magnetic cycles. The third planet is a 0.77 Neptune-mass-planet in circular orbit around the K4 dwarf, HD 12595, with a 9.67-day-period. Finally, HIP 7849 bis a long-period (5  <  P<  75 years) and massive planet of msin i≈  3.5−15 MJupthat orbits a late K7 dwarf.

Context.In 2009 we started an intense radial-velocity monitoring of a few nearby, slowly-rotating and quiet solar-type stars within the dedicated HARPS-Upgrade GTO program.

We report on the detection of a transit of the super-Earth 55 Cnc e with warm Spitzer in IRAC’s 4.5 μm band. Our MCMC analysis includes an extensive modeling of the systematic effects affecting warm Spitzer photometry, and yields a transit depth of 410 ± 63 ppm, which translates to a planetary radius of \hbox{$2.08^{+0.16}_{-0.17}\: R_\oplus$}as measured in IRAC 4.5 μm channel. A planetary mass of \hbox{$7.81_{-0.53}^{+0.58}\: M_\oplus$}is derived from an extensive set of radial-velocity data, yielding a mean planetary density of \hbox{$4.78_{-1.20}^{+1.31}$}g cm-3. Thanks to the brightness of its host star (V= 6, K= 4), 55 Cnc e is a unique target for the thorough characterization of a super-Earth orbiting around a solar-type star.

We report the measurement of the spin-orbit angle of the extra-solar planets HAT-P-8 b, HAT-P-9 b, HAT-P-16 b, and HAT-P-23 b, based on spectroscopic observations performed at the Observatoire de Haute-Provence with the SOPHIE spectrograph on the 1.93-m telescope. Radial velocity measurements of the Rossiter-McLaughlin effect show the detection of an apparent prograde, aligned orbit for all systems. The projected spin-orbit angles are found to be λ= −17°\hbox{$^{+9.2}_{-11.5}$}, −16° ± 8°, –10° ± 16°, and +15° ± 22° for HAT-P-8, HAT-P-9, HAT-P-16, and HAT-P-23, respectively, with corresponding projected rotational velocities of 14.5 ± 0.8, 12.5 ± 1.8, 3.9 ± 0.8, and 7.8 ± 1.6  km s-1. These new results increase to 37 the number of accurately measured spin-orbit angles in transiting extrasolar systems. We conclude by drawing a tentative picture of the global behaviour of orbital alignement, involving the complexity and diversity of possible mechanisms.

We report the discovery of the low-density, transiting giant planet WASP-31b. The planet is 0.48 Jupiter masses and 1.55 Jupiter radii. It is in a 3.4-day orbit around a metal-poor, late-F-type, V= 11.7 dwarf star, which is a member of a common proper motion pair. In terms of its low density, WASP-31b is second only to WASP-17b, which is a more highly irradiated planet of similar mass.

We report the discovery of a new transiting planet in the southern hemisphere. It was found by the WASP-south transit survey and confirmed photometrically and spectroscopically by the 1.2 m Swiss Euler telescope, LCOGT 2m Faulkes South Telescope, the 60 cm TRAPPIST telescope, and the ESO 3.6 m telescope. The orbital period of the planet is 2.94 days. We find that it is a gas giant with a mass of 0.88 ± 0.10   MJand an estimated radius of 0.96 ± 0.05   RJ. We obtained spectra during transit with the HARPS spectrograph and detect the Rossiter-McLaughlin effect despite its small amplitude. Because of the low signal-to-noise ratio of the effect and a small impact parameter, we cannot place a strong constraint on the projected spin-orbit angle. We find two conflicting values for the stellar rotation. We find, via spectral line broadening, that vsin   I= 2.2 ± 0.3 km s-1, while applying another method, based on the activity level using the index \hbox{$\log\,R'_{\rm HK}$}, gives an equatorial rotation velocity of only v= 1.35 ± 0.20 km s-1. Using these as priors in our analysis, the planet might be either misaligned or aligned. This result raises doubts about the use of such priors. There is evidence of neither eccentricity nor any radial velocity drift with time.

We examined six exoplanet host stars with non-standard Hipparcos astrometric solution, which may be indicative of unrecognised orbital motion. Using Hipparcos intermediate astrometric data, we detected the astrometric orbit of HD 5388 at a significance level of 99.4% (2.7   σ). HD 5388 is a metal-deficient star and hosts a planet candidate with a minimum mass of 1.96   MJdiscovered in 2010. We determined its orbit inclination to be \hbox{$i =178.3^{+0.4\,\circ}_{- 0.7}$}and the corresponding mass of its companion HD 5388 bto be M2= 69 ± 20   MJ. The orbit is seen almost face-on and the companion mass lies at the upper end of the brown-dwarf mass range. A mass lower than 13   MJwas excluded at the 3   σ-level. The astrometric motions of the five other stars had been investigated by other authors revealing two planetary companions, one stellar companion, and two statistically insignificant orbits. We conclude that HD 5388 b is not a planet but most likely a brown-dwarf companion. In addition, we find that the inclinations of the stellar rotation axis and the companion’s orbital axis differ significantly.

Context.Low-mass extrasolar planets are presently being discovered at an increased pace by radial velocity and transit surveys, which opens a new window on planetary systems.

We are conducting a planet search survey with HARPS since seven years. The volume-limited stellar sample includes all F2 to M0 main-sequence stars within 57.5 pc, where extrasolar planetary signatures are systematically searched for with the radial-velocity technics. In this paper, we report the discovery of new substellar companions of seven main-sequence stars and one giant star, detected through multiple Doppler measurements with the instrument HARPS installed on the ESO 3.6 m telescope, La Silla, Chile. These extrasolar planets orbit the stars HD 1690, HD 25171, HD 33473A, HD 89839, HD 113538, HD 167677, and HD 217786. The already-published giant planet around HD 72659 is also analysed here, and its elements are better determined by the addition of HARPS and Keck data. The other discoveries are giant planets in distant orbits, ranging from 0.3 to 29 MJupin mass and between 0.7 and 10 years in orbital period. The low metallicity of most of these new planet-hosting stars reinforces the current trend for long-distance planets around metal-poor stars.

We observed the transit of the HAT-P-6b exoplanet across its host star with the SOPHIE spectrograph (OHP, France). The resulting stellar radial velocities display the Rossiter-McLaughlin anomaly and reveal a retrograde orbit: the planetary orbital spin and the stellar rotational spin point in approximately opposite directions. A fit to the anomaly measures a sky-projected angle λ= 166° ± 10° between these two spin axes. All seven known retrograde planets are hot Jupiters with masses Mp< 3   MJup. About two thirds of the planets in this mass range, however, are prograde and aligned (λ≃ 0°). In contrast, most of the more massive planets (Mp> 4   MJup) are prograde but misaligned. Different mechanisms may therefore be responsible for planetary obliquities above and below  ~3.5   MJup.

We observed VB 10 in August and September 2009 using the FORS2 camera of the VLT with the aim of measuring its astrometric motion and of probing for the presence of the announced planet VB  10b. We used the published STEPS astrometric positions of VB 10 over a timespan of 9 years, which allowed us to compare the expected motion of VB 10 due to parallax and proper motion with the observed motion and to compute precise deviations. The single-epoch precisions of our observations are about 0.1 mas, and the data showed no significant residual trend, while the presence of the planet should have induced an apparent proper motion greater than 10 mas yr-1. Subtraction of the predicted orbital motion from the observed data produces a strong trend in position residuals of VB 10. We estimated the probability that this trend is caused by random noise. After taking all the uncertainties into account and using Monte-Carlo resampling of the data, we are able to reject the existence of VB 10b with the announced mass of 6.4 MJwith a false alarm probability of only 5 × 10-4. A 3.2 MJplanet is also rejected with a false alarm probability of 0.023.

Searching for extrasolar planets around stars of different metallicity may provide strong constraints to the models of planet formation and evolution. In this paper we present the overall results of a HARPS (a high-precision spectrograph mostly dedicated to deriving precise radial velocities) program to search for planets orbiting a sample of 104 metal-poor stars (selected [Fe/H] below −0.5). Radial velocity time series of each star are presented and searched for signals using several statistical diagnostics. Stars with detected signals are presented, including 3 attributed to the presence of previously announced giant planets orbiting the stars HD 171028, HD 181720, and HD 190984. Several binary stars and at least one case of a coherent signal caused by activity-related phenomena are presented. One very promising new, possible giant planet orbiting the star HD 107094 is discussed, and the results are analyzed in light of the metallicity-giant planet correlation. We conclude that the frequency of giant planets orbiting metal-poor stars may be higher than previously thought, probably reflecting the higher precision of the HARPS survey. In the metallicity domain of our sample, we also find evidence that the frequency of planets is a steeply rising function of the stellar metal content, as found for higher metallicity stars.

We report the detection of three new extrasolar planets orbiting the solar type stars HD 85390, HD 90156and HD 103197with the HARPS spectrograph mounted on the ESO 3.6-m telescope at La Silla observatory. HD 85390has a planetary companion with a projected intermediate mass (42.0   M⊕) on a 788-day orbit (a= 1.52 AU) with an eccentricity of 0.41, for which there is no analog in the solar system. A drift in the data indicates the presence of another companion on a long-period orbit, which is however not covered by our measurements. HD 90156is orbited by a warm Neptune analog with a minimum mass of 17.98 M⊕(1.05  $M_{\neptune}$), a period of 49.8 days (a= 0.25 AU), and an eccentricity of 0.31. HD 103197has an intermediate-mass planet on a circular orbit (P= 47.8 d, Msini= 31.2   M⊕). We discuss the formation of planets of intermediate mass (~30–100 M⊕), which should be rare inside a few AU according to core accretion formation models.

The Keplermission has detected transits and occultations of a hot compact object around an early-type star, the Kepler Object of Interest KOI 74. The mass of this transiting object was photometrically assessed in a previous study using the presence of the relativistic beaming effect (so-called “Doppler boosting”) in the light curve. Our aim was to provide a spectroscopic validation of this pioneering approach. We measured the radial velocity variations of the A1V star KOI 74with the SOPHIE spectrograph at the 1.93-m telescope of the Observatoire de Haute-Provence (France). Radial velocity measurements of this star are challenging because of the high level of stellar pulsations and the few available spectral lines. Using a technique dedicated to early-type main-sequence stars, we measured radial velocity variations compatible with a companion of mass 0.252 ± 0.025 M⊙, in good agreement with the value derived from the Keplerlight curve. This work strengthens the scenario suggesting that KOI 74 is a blue straggler orbited by a stellar core despoiled of its envelope, the low-mass white dwarf KOI 74b.