Context. Young circumstellar disks are the birthplaces of planets. Their study is of prime interest to understand the physical and chemical conditions under which planet formation takes place. Only very few detections of planet candidates within these disks exist, and most of them are currently suspected to be disk features. Aims. In this context, the transition disk around the young star PDS 70 is of particular interest, due to its large gap identified in previous observations, indicative of ongoing planet formation. We aim to search for the presence of an embedded young planet and search for disk structures that may be the result of disk-planet interactions and other evolutionary processes. Methods. We analyse new and archival near-infrared (NIR) images of the transition disk PDS 70 obtained with the VLT/SPHERE, VLT/NaCo and Gemini/NICI instruments in polarimetric differential imaging (PDI) and angular differential imaging (ADI) modes. Results. We detect a point source within the gap of the disk at about 195 mas (∼22 au) projected separation. The detection is confirmed at five different epochs, in three filter bands and using different instruments. The astrometry results in an object of bound nature, with high significance.The comparison of the measured magnitudes and colours to evolutionary tracks suggests that the detection is a companion of planetary mass. The luminosity of the detected object is consistent with that of an L-type dwarf, but its IR colours are redder, possibly indicating the presence of warm surrounding material. Further, we confirm the detection of a large gap of ∼54 au in size within the disk in our scattered light images, and detect a signal from an inner disk component. We find that its spatial extent is very likely smaller than ∼17 au in radius, and its position angle is consistent with that of the outer disk. The images of the outer disk show evidence of a complex azimuthal brightness distribution which is different at different wavelengths and may in part be explained by Rayleigh scattering from very small grains. Conclusions. The detection of a young protoplanet within the gap of the transition disk around PDS 70 opens the door to a so far observationally unexplored parameter space of planetary formation and evolution. Future observations of this system at different wavelengths and continuing astrometry will allow us to test theoretical predictions regarding planet-disk interactions, planetary atmospheres and evolutionary models.Based on observations performed with ESO Telescopes at the Paranal Observatory under programmes 095.C-0298, 095.C-0404, 096.C-0333, 097.C-0206, 097.C-1001, 099.C-0891. are imprinted by the initial conditions of the disks and which develop through a variety of dynamical interactions is crucial for understanding the planet population. It is therefore of high importance to study planets and their environments at the stage during which these objects are formed. Transition disks (TDs) are of key interest in this context, as many of them are believed to bear direct ...

Context. Imaged in the gap of a transition disk and found at a separation of about 195 mas (∼22 au) from its host star at a position angle of about 155 o , PDS 70 b is the most robustly detected young planet to date. This system is therefore a unique laboratory for characterizing the properties of young planetary systems at the stage of their formation. Aims. We aim to trace direct and indirect imprints of PDS 70 b on the gas and dust emission of the circumstellar disk in order to study the properties of this ∼5 Myr young planetary system. Methods. We obtained ALMA band 7 observations of PDS 70 in dust continuum and 12 CO (3 − 2) and combined them with archival data. This resulted in an unprecedented angular resolution of about 70 mas (∼8 au). Results. We derive an upper limit on circumplanetary material at the location of PDS 70 b of ∼0.01 M ⊕ and find a highly structured circumstellar disk in both dust and gas. The outer dust ring peaks at 0.65 (74 au) and reveals a possible second unresolved peak at about 0.53 (60 au). The integrated intensity of CO also shows evidence of a depletion of emission at ∼0.2 (23 au) with a width of ∼0.1 (11 au). The gas kinematics show evidence of a deviation from Keplerian rotation inside 0.8 (91 au). This implies a pressure gradient that can account for the location of the dust ring well beyond the location of PDS 70 b. Farther in, we detect an inner disk that appears to be connected to the outer disk by a possible bridge feature in the northwest region in both gas and dust. We compare the observations to hydrodynamical simulations that include a planet with different masses that cover the estimated mass range that was previously derived from near-infrared photometry (∼5-9 M Jup ). We find that even a planet with a mass of 10 M Jup may not be sufficient to explain the extent of the wide gap, and an additional low-mass companion may be needed to account for the observed disk morphology.

Context. The observation of planets in their formation stage is a crucial, but very challenging step in understanding when, how and where planets form. PDS 70 is a young pre-main sequence star surrounded by a transition disk, in the gap of which a planetary-mass companion has been discovered recently. This discovery represents the first robust direct detection of such a young planet, possibly still at the stage of formation. Aims. We aim to characterize the orbital and atmospheric properties of PDS 70 b, which was first identified on May 2015 in the course of the SHINE survey with SPHERE, the extreme adaptive-optics instrument at the VLT. Methods. We obtained new deep SPHERE/IRDIS imaging and SPHERE/IFS spectroscopic observations of PDS 70 b. The astrometric baseline now covers 6 years which allows us to perform an orbital analysis. For the first time, we present spectrophotometry of the young planet which covers almost the entire near-infrared range (0.96 to 3.8 µm). We use different atmospheric models covering a large parameter space in temperature, log g, chemical composition, and cloud properties to characterize the properties of the atmosphere of PDS 70 b. Results. PDS 70 b is most likely orbiting the star on a circular and disk coplanar orbit at ∼22 au inside the gap of the disk. We find a range of models that can describe the spectrophotometric data reasonably well in the temperature range between 1000-1600 K and log g no larger than 3.5 dex. The planet radius covers a relatively large range between 1.4 and 3.7 R J with the larger radii being higher than expected from planet evolution models for the age of the planet of 5.4 Myr.Conclusions. This study provides a comprehensive dataset on the orbital motion of PDS 70 b, indicating a circular orbit and a motion coplanar with the disk. The first detailed spectral energy distribution of PDS 70 b indicates a temperature typical for young giant planets. The detailed atmospheric analysis indicates that a circumplanetary disk may contribute to the total planet flux.

Aims. The SHINE program is a high-contrast near-infrared survey of 600 young, nearby stars aimed at searching for and characterizing new planetary systems using VLT/SPHERE's unprecedented high-contrast and high-angular-resolution imaging capabilities. It is also intended to place statistical constraints on the rate, mass and orbital distributions of the giant planet population at large orbits as a function of the stellar host mass and age to test planet-formation theories. Methods. We used the IRDIS dual-band imager and the IFS integral field spectrograph of SPHERE to acquire high-contrast coronagraphic differential near-infrared images and spectra of the young A2 star HIP 65426. It is a member of the ∼ 17 Myr old Lower Centaurus-Crux association. Results. At a separation of 830 mas (92 au projected) from the star, we detect a faint red companion. Multi-epoch observations confirm that it shares common proper motion with HIP 65426. Spectro-photometric measurements extracted with IFS and IRDIS between 0.95 and 2.2 µm indicate a warm, dusty atmosphere characteristic of young low-surface-gravity L5-L7 dwarfs. Hot-start evolutionary models predict a luminosity consistent with a 6 − 12 M Jup , T eff = 1300 − 1600 K and R = 1.5 ± 0.1 R Jup giant planet. Finally, the comparison with Exo-REM and PHOENIX BT-Settl synthetic atmosphere models gives consistent effective temperatures but with slightly higher surface gravity solutions of log(g) = 4.0−5.0 with smaller radii (1.0 − 1.3 R Jup ). Conclusions. Given its physical and spectral properties, HIP 65426 b occupies a rather unique placement in terms of age, mass, and spectral-type among the currently known imaged planets. It represents a particularly interesting case to study the presence of clouds as a function of particle size, composition, and location in the atmosphere, to search for signatures of non-equilibrium chemistry, and finally to test the theory of planet formation and evolution.

Context. 51 Eridani b is an exoplanet around a young (20 Myr) nearby (29.4 pc) F0-type star, recently discovered by direct imaging. It is one of the closest direct imaging planets in angular and physical separation (∼0.5 , ∼13 au) and is well suited for spectroscopic analysis using integral field spectrographs. Aims. We aim to refine the atmospheric properties of the known giant planet and to further constrain the architecture of the system by searching for additional companions. Methods. We use the extreme adaptive optics instrument SPHERE at the VLT to obtain simultaneous dual-band imaging with IRDIS and integral field spectra with IFS, extending the spectral coverage of the planet to the complete Y-to H-band range and provide additional photometry in the K12-bands (2.11, 2.25 µm). The object is compared to other known cool and peculiar dwarfs. Furthermore, the posterior probability distributions for parameters of cloudy and clear atmospheric models are explored using MCMC. We verified our methods by determining atmospheric parameters for the two benchmark brown dwarfs Gl 570D and HD 3651B. For probing the innermost region for additional companions, archival VLT-NACO (L') Sparse Aperture Masking data is used. Results. We present the first spectrophotometric measurements in the Y-and K-bands for the planet and revise its J-band flux to values 40% fainter than previous measurements. Cloudy models with uniform cloud coverage provide a good match to the data. We derive the temperature, radius, surface gravity, metallicity and cloud sedimentation parameter f sed . We find that the atmosphere is highly super-solar ([Fe/H] = 1.0 ± 0.1 dex), and the low f sed = 1.26 +0.36 −0.29 value is indicative of a vertically extended, optically thick cloud cover with small sized particles. The model radius and surface gravity estimates suggest higher planetary masses of M gravity = 9.1 +4.9 −3.3 M J . The evolutionary model only provides a lower mass limit of > 2 M J (for pure hot-start). The cold-start model cannot explain the planet's luminosity. The SPHERE and NACO/SAM detection limits probe the 51 Eri system at solar system scales and exclude brown-dwarf companions more massive than 20 M J beyond separations of ∼2.5 au and giant planets more massive than 2 M J beyond 9 au. A recent dynamical mass estimate of the distant binary M-dwarf companion GJ 3305 predict an older age of the GJ 3305 AB system of 37 ± 9 Myr. An astrometric follow-up paper by De Rosa et al. (2015) confirmed that the planet is co-moving with 51 Eri. The tentative orbital solutions (semimajor axis a = 14 +7 −3 au, orbital period T = 41 +35 −13 years, inclination i = 138 +15 −13 ) suggest that the planet does not share the inclination of the distant M-dwarf companion GJ 3305 (Montet et al. 2015). The host star also has an infrared excess that can be modeled by two components corresponding to a warm belt of debris at 5.5 AU and another colder one at 82 AU (Patel et al. 2014;Riviere-Marichalar et al. 2014). As such, the architecture of 51 Eri is reminiscent of o...