Jean-Luc Beuzit

HD 80606 b, a planet on an extremely elongated orbit ?

We report the detection of a planetary companion orbiting the solar-type star HD 80606, the brighter component of a wide binary with a projected separation of about 2000 AU. Using high-signal spectroscopic observations of the two components of the visual binary, we show that they are nearly identical. The planet has an orbital period of 111.8 days and a minimum mass of 3:9MJup .W ithe = 0.927, this planet has the highest orbital eccentricity among the extrasolar planets detected so far. We nally list several processes this extreme eccentricity could result from.

The impact of stellar duplicity on planet occurrence and properties I. Observational results of a VLT/NACO search for stellar companions to 130 nearby stars with and without planets ,

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. Aims. In an effort to bring observational constraints on the occurrence and properties of planets in binaries and multiple stars, we have been conducting a dedicated investigation, the results of which will be presented in this series. Methods. Our investigation follows two different approaches, one based on radial-velocity monitoring, the other based on direct imaging. In this first paper, we present the observational results from our systematic adaptive optics search with VLT/NACO for close stellar companions to 130 nearby stars, 57 with planets and 73 without, for comparison. The inclusion of a control sub-sample is a unique feature of our program that will enable a meaningful and rigorous comparison between the properties of planet-host stars and the properties of field stars subject to the same selection effects against close binaries, but showing no evidence for planetary companions. Results. Our data reveal 95 companion candidates found in the vicinity of 33 of our targets. Nineteen of these candidates are true companions and 2 are likely bound objects. Among planet-host stars, we discovered a tight pair of very low mass companions to HD 65216 (projected separation of 255 AU), an early M companion to HD 177830 (projected separation of 97 AU), and we resolved the previously known companion to HD 196050 into a close pair of M dwarfs. Our data additionally confirm the bound nature of the companions to HD 142, HD 16141, and HD 46375. Among control stars, we detected true companions to HD 7895, HD 24331, HD 31412, HD 40397, HD 43834, HD 70923, HD 78351, HD 104263, HD 129642, HD 154682, and HD 223913, and likely bound companions to HD 82241 and HD 134180. Most of these objects are M dwarfs and have projected separations between 7 and 505 AU.

Extrasolar planets and brown dwarfs around A-F type stars - I. Performances of radial velocity measurements, first analyses of variations

We present the performances of a radial velocity measurement method that we developed for A-F type stars. These perfomances are evaluated through an extensive set of simulations, together with actual radial velocity observations of such stars using the ELODIE and HARPS spectrographs. We report the case of stars constant in radial velocity, the example of a binary detection on HDu200948097 (an A2V star, with

The ELODIE survey for northern extra-solar planets - III. Three planetary candidates detected with ELODIE

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Dissecting the Moth: discovery of an off-centered ring in the HD 61005 debris disk with high-resolution imaging

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New neighbours - III. 21 new companions to nearby dwarfs, discovered with adaptive optics

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The ELODIE survey for northern extra-solar planets - IV. HD 196885, a close binary star with a 3.7-year planet

) and a confirmation of the existence of a 3.9xa0 M Jup planet orbiting around HDu2009120136 (Tau Boo). The instability strip problem is also discussed. We show that with this method, it is in principle possible to detect planets and brown dwarfs around A-F type stars, thus allowing further study of the impact of stellar masses on planetary system formation over a wider range of stellar masses than is currently done.

The ELODIE survey for northern extra-solar planets. I. Six new extra-solar planet candidates

We present our ELODIE radial-velocity measurements of HD 74156 and 14 Her (HD 145675). These stars ex- hibit low-amplitude radial-velocity variations induced by the presence of low-mass companions. The radial-velocity data of HD 74156 reveal the presence of two planetary companions: a 1.86 MJup planet on a 51.64-d orbit and a 6.2 MJup planet on a long-period (� 5.5 yr) orbit. Both orbits are fairly eccentric (e = 0.64 and 0.58). The 4.7 MJup companion to 14 Her has a long period (4.9 yr) and a moderately eccentric orbit (e = 0.34). We detect an additional linear radial-velocity trend superimposed on the periodic signal for this star. We also compute updated orbital solutions for HD 209458 and 51 Peg (HD 217014). Finally, we present our ELODIE radial-velocity data and orbital solutions for 5 stars known to host planetary companions: Ups And (HD 9826), 55 Cnc (HD 75732), 47 UMa (HD 95128), 70 Vir (HD 117176) and HD 187123. We confirm the previously pub- lished orbital solutions for Ups And, 70 Vir and HD 187123. Our data are not sufficient to fully confirm the orbital solutions for 55 Cnc and 47 UMa.

Extrasolar planets and brown dwarfs around A-F type stars. IV. A candidate brown dwarf around the A9V pulsating star HD 180777

The debris disk known as “The Moth” is named after its unusually asymmetric surface brightness distribution. It is locat ed around the � 90 Myr old G8V star HD 61005 at 34.5 pc and has previously been imaged by the HST at 1.1 and 0.6� m. Polarimetric observations suggested that the circumstellar material consists of two d istinct components, a nearly edge-on disk or ring, and a swept-back feature, the result of interaction with the interstellar medium. We r esolve both components at unprecedented resolution with VLT/NACO Hband imaging. Using optimized angular differential imaging techniques to remove the light of the star, we reveal the disk component as a distinct narrow ring at inclination i = 84: 3�1: 0 � . We determine a semi-major axis of a = 61: 25�0: 85 AU and an eccentricity of e = 0: 045�0: 015, assuming that periastron is located along the apparent disk major axis. Therefore, the ring center is offset from the star by at least 2: 75�0: 85 AU. The offset, together with a relatively steep inner rim, could indic ate a planetary companion that perturbs the remnant planetesimal belt. From our imaging data we set upper mass limits for companions that exclude any object above the deuterium-burning limit for separations down to 0: 00 3. The ring shows a strong brightness asymmetry along both the major and minor axis. A brighter front side could indicate forward-scattering grains, while the brightness difference between the NE and SW components can be only partly explained by the ring center offset, suggesting additional density enhancements on one side of the ring. The swept-back component appears as two streamers originating near the NE and SW edges of the debris ring.

Extrasolar planets and brown dwarfs around A–F type stars - II. A planet found with ELODIE around the F6V star HD 33564

Received ; accepted Abstract. 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 fair fraction of the new binaries has favourable parameters for accurate mass determinations. The newly resolved companion of Gl 120.1C had an apparent spectroscopic minimum mass in the brown-dwarf range (Duquennoy & Mayor 1991), 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 (1991), 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 does straddle 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.