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Direct imaging has just started the inventory of the population of gas giant planets on wideorbits around young stars in the solar neighborhood. Following this approach, we carried out a deep imaging survey in the near-infrared using VLT/NaCo to search for substellar companions. We report here the discovery in L ' (3.8 µm) images of a probable companion orbiting at 56 AU the young (10 − 17 Myr), dusty, and early-type (A8) star HD 95086. This discovery is based on observations with more than a year-time-lapse. Our first epoch clearly revealed the source at ≃ 10 σ while our second epoch lacked good observing conditions hence yielding a ≃ 3 σ detection. Various tests were thus made to rule out possible artifacts. This recovery is consistent with the signal at the first epoch but requires cleaner confirmation. Nevertheless, our astrometric precision suggests the companion to be comoving with the star, with a 3 σ confidence level. The planetary nature of the source is reinforced by a non-detection in Ks-band (2.18 µm) images according to its possible extremely red Ks -L ' color. Conversely, background contamination is rejected with good confidence level. The luminosity yields a predicted mass of about 4 − 5 M Jup (at 10 − 17 Myr) using "hot-start" evolutionary models, making HD 95086 b the exoplanet with the lowest mass ever imaged around a star.

Understanding the formation and evolution of giant planets (≥1 M Jup ) at wide orbital separation (≥5 AU) is one of the goals of direct imaging. Over the past 15 yr, many surveys have placed strong constraints on the occurrence rate of wide-orbit giants, mostly based on non-detections, but very few have tried to make a direct link with planet formation theories. In the present work, we combine the results of our previously published VLT/NaCo large program with the results of 12 past imaging surveys to constitute a statistical sample of 199 FGK stars within 100 pc, including three stars with sub-stellar companions. Using Monte Carlo simulations and assuming linear flat distributions for the mass and semi-major axis of planets, we estimate the sub-stellar companion frequency to be within 0.75-5.70% at the 68% confidence level (CL) within 20-300 AU and 0.5-75 M Jup , which is compatible with previously published results. We also compare our results with the predictions of state-of-the-art population synthesis models based on the gravitational instability (GI) formation scenario with and without scattering. We estimate that in both the scattered and non-scattered populations, we would be able to detect more than 30% of companions in the 1-75 M Jup range (95% CL). With the three sub-stellar detections in our sample, we estimate the fraction of stars that host a planetary system formed by GI to be within 1.0-8.6% (95% CL). We also conclude that even though GI is not common, it predicts a mass distribution of wide-orbit massive companions that is much closer to what is observed than what the core accretion scenario predicts. Finally, we associate the present paper with the release of the Direct Imaging Virtual Archive (DIVA), a public database that aims at gathering the results of past, present, and future direct imaging surveys.

Context. Young, nearby stars are ideal targets for direct imaging searches for giant planets and brown dwarf companions. After the first-imaged planet discoveries, vast efforts have been devoted to the statistical analysis of the occurence and orbital distributions of giant planets and brown dwarf companions at wide (≥5-6 AU) orbits. Aims. In anticipation of the VLT/SPHERE planet-imager, guaranteed-time programs, we have conducted a preparatory survey of 86 stars between 2009 and 2013 to identify new faint comoving companions to ultimately analyze the occurence of giant planets and brown dwarf companions at wide (10-2000 AU) orbits around young, solar-type stars. Methods. We used NaCo at VLT to explore the occurrence rate of giant planets and brown dwarfs between typically 0.1 and 8 . Diffraction-limited observations in H-band combined with angular differential imaging enabled us to reach primary star-companion brightness ratios as small as 10 −6 at 1.5 . Repeated observations at several epochs enabled us to discriminate comoving companions from background objects. Results. During our survey, twelve systems were resolved as new binaries, including the discovery of a new white dwarf companion to the star HD 8049. Around 34 stars, at least one companion candidate was detected in the observed field of view. More than 400 faint sources were detected; 90% of them were in four crowded fields. With the exception of HD 8049 B, we did not identify any new comoving companions. The survey also led to spatially resolved images of the thin debris disk around HD 61005 that have been published earlier. Finally, considering the survey detection limits, we derive a preliminary upper limit on the frequency of giant planets for the semi-major axes of [10, 2000] AU: typically less than 15% between 100 and 500 AU and less than 10% between 50 and 500 AU for exoplanets that are more massive than 5 M Jup and 10 M Jup respectively, if we consider a uniform input distribution and a confidence level of 95%. Conclusions. The results from this survey agree with earlier programs emphasizing that massive, gas giant companions on wide orbits around solar-type stars are rare. These results will be part of a broader analysis of a total of ∼210 young, solar-type stars to bring further statistical constraints for theoretical models of planetary formation and evolution.

Context. The high number of planet discoveries made in the last years provides a good sample for statistical analysis, leading to some clues on the distributions of planet parameters, such as masses and periods, at least in close proximity to the host star. We likely need to wait for the extremely large telescopes (ELTs) to have an overall view of the extrasolar planetary systems. Those facilities will finally ensure an overlap of the discovery space of direct and indirect techniques, which is desirable to completely understand the nature of the discovered objects, obtaining both orbital parameters and physical characterization. Aims. In this context it would be useful to have a tool that can be used for the interpretation of the present results that are obtained with various observing techniques, and also to predict what the outcomes would be of the future instruments. Methods. For this reason we built MESS: a Monte Carlo simulation code that uses either the results of the statistical analysis of the properties of discovered planets or the results of the planet formation theories to build synthetic planet populations that are fully described in terms of frequency, orbital elements and physical properties. These synthetic planets can then be used to either test the consistency of their properties with the observed ones given different detection techniques (radial velocity, imaging and astrometry) or to predict the expected number of planets for future surveys, as well as to optimize the future multi-technique observations for their characterization down to telluric masses. Results. In addition to the code description, we present here some of its applications to probe the physical and orbital properties of a putative companion within the circumstellar disk of a given star and to test or constrain the orbital distribution properties of a potential planet population around the members of the TW Hydrae association. Finally, we investigated the synergy of future space and ground-based telescopes instrumentation with the predictive mode of the code, to identify the mass-period parameter space that will be probed in future surveys for giant and rocky planets.