Search

We present the re-detection of a compact source in the face-on protoplanetary disc surrounding HD 169142, using VLT/SPHERE data in YJH bands. The source is found at a separation of 0.''319 ($\sim$37 au) from the star. Three lines of evidence argue in favour of the signal tracing a protoplanet: (i) it is found in the annular gap separating the two bright rings of the disc, as predicted by theory; (ii) it is moving at the expected Keplerian velocity for an object at $\sim$37 au in the 2015, 2017 and 2019 datasets; (iii) we also detect a spiral-shaped signal whose morphology is consistent with the expected outer spiral wake triggered by a planet in the gap, based on dedicated hydrodynamical simulations of the system. The YJH colours we extracted for the object are consistent with tracing scattered starlight, suggesting that the protoplanet is enshrouded in a significant amount of dust, as expected for a circumplanetary disc or envelope surrounding a gap-clearing Jovian-mass protoplanet., Comment: Accepted for publication in MNRAS Letters. 5 pages, 5 figures

Observing dynamical interactions between planets and disks is key to understanding their formation. Two protoplanets have recently been observed within PDS 70's transition disk, along with an extended signal towards the north-west of the star. In this contribution, I will present a temporal analysis of the PDS 70 disk morphology with the aim of assessing whether it could trace a spiral arm caused by the dynamical interaction between the planet PDS 70 c and the disk - or rather be the footprint of a vortex, which can mimic a spiral-arm in an inclined disk. I will show the PDI and ADI images obtained with SPHERE-IRDIS spanning 6 years of observations. We reduced PDI datasets through the IRDAP polarimetric data reduction pipeline (for PDI data) and a novel algorithm that we developed (MUSTARD, for ADI data). I will explain the principle of our inverse-problem based MUSTARD algorithm. I will then show the trace of the potential spiral that we inferred by identifying local radial maxima in azimuthal slices of the disc in each dataset. I will then compare the measured traces with the expected motion of a spiral launched by planet c - i.e. in rigid-body motion. I will show how the traces seem to perfectly align in all datasets, and will finally discuss the implications of our results on the nature of this extended feature.

With its large sub-mm continuum cavity, asymmetric clumps and spiral arms, the disc of MWC 758 is an ideal test laboratory to search for embedded planets at an early stage of formation and study their dynamical interplay with the disc. As such, two protoplanet candidates have been proposed in this disc by independent teams based on thermal IR high-contrast imaging data, which both require confirmation. In this contribution, I will compare three novel algorithms that we designed to alleviate current shortcomings stemming from the application of state-of-the-art Angular Differential Imaging (ADI)-based algorithms - namely geometric biases induced to azimuthally extended signals from the aggressive modeling and subtraction of the stellar halo. The first algorithm relies on an iterative approach, while the other two rely on an inverse-problem approach, with and without regularisation terms, respectively, to recover the unbiased circumstellar intensity distribution. I will show the images obtained from the application of these algorithms to the case of MWC 758, for which we considered the SPHERE (H23) and NIRC2 (L’) datasets obtained in the best observing conditions for this study. I will then compare these images to predictions from hydro-dynamical simulations testing the hypotheses of a single (internal) eccentric companion, and two giant (internal+external) planets on circular orbits, respectively, and will discuss the likelihood of each scenario based on the similarity to our new images.

Planet-disc interactions build up local pressure maxima that may halt the radial drift of protoplanetary dust, and pile it up in rings and crescents. ALMA observations of the HD135344B disc revealed two rings in the thermal continuum stemming from ~mm-sized dust. At higher frequencies the inner ring is brighter relative to the outer ring, which is also shaped as a crescent rather than a full ring. In near-IR scattered light images, the disc is modulated by a 2-armed grand-design spiral originating inside the ALMA inner ring. Such structures may be induced by a massive companion evacuating the central cavity, and by a giant planet in the gap separating both rings, that channels the accretion of small dust and gas through its filamentary wakes while stopping the larger dust from crossing the gap. Here we present ALMA observations in the J=(2-1)CO isotopologue lines and in the adjacent continuum, with up to 12km baselines. Angular resolutions of 0.03" reveal the tentative detection of a filament connecting both rings, and which coincides with a local discontinuity in the pitch angle of the IR spiral, proposed previously as the location of the protoplanet driving this spiral. Line diagnostics suggest that turbulence, or superposed velocity components, is particularly strong in the spirals. The 12CO(2-1) 3-D rotation curve points at stellocentric accretion at radii within the inner dust ring, with a radial velocity of up to ~6%+-0.5% Keplerian, which corresponds to an excessively large accretion rate of ~2E-6M_sun/yr if all of the CO layer follows the 12CO(2-1) kinematics. This suggests that only the surface layers of the disc are undergoing accretion, and that the line broadening is due to superposed laminar flows., accepted to MNRAS

We present ALMA observations of the $^{12}$CO, $^{13}$CO, C$^{18}$O J=2-1 transitions and the 1.3\,mm continuum emission for the circumbinary disc around HD 142527, at an angular resolution of $\approx$\,0\farcs3. We observe multiple spiral structures in intensity, velocity and velocity dispersion for the $^{12}$CO and $^{13}$CO gas tracers. A newly detected $^{12}$CO spiral originates from the dust horseshoe, and is rotating at super-Keplerian velocity or vertically ascending, whilst the inter-spiral gas is rotating at sub-Keplerian velocities. This new spiral possibly connects to a previously identified spiral, thus spanning > 360$^\circ$. A spatial offset of ~30 au is observed between the $^{12}$CO and $^{13}$CO spirals, to which we hypothesize that the gas layers are propagating at different speeds (``surfing'') due to a non-zero vertical temperature gradient. Leveraging the varying optical depths between the CO isotopologues, we reconstruct temperature and column density maps of the outer disc. Gas surface density peaks at r\,$\approx$\,180\,au, coincident with the peak of continuum emission. Here the dust grains have a Stokes number of $\approx$\,1, confirming radial and azimuthal trapping in the horseshoe. We measure a cavity radius at half-maximum surface density of $\approx$\,100\,au, and a cavity eccentricity between 0.3 and 0.45.

Companions at sub-arcsecond separation from young stars are difficult to image. However their presence can be inferred from the perturbations they create in the dust and gas of protoplanetary disks. Here we present a new interpretation of SPHERE polarised observations that reveal the previously detected inner spiral in the disk of HD 100546. The spiral coincides with a newly detected 12CO inner spiral and the previously reported CO emission Doppler-flip, which has been interpreted as the signature of an embedded protoplanet. Comparisons with hydrodynamical models indicate that this Doppler-flip is instead the kinematic counterpart of the spiral, which is likely generated by an inner companion inside the disk cavity., Comment: Accepted to ApJL, 14 pages, 10 figures

We present the highest fidelity spectrum to date of a planetary-mass object. VHS 1256 b is a $, Comment: Accepted ApJL Iterations of spectra reduced by the ERS team are hosted at this link: https://github.com/bemiles/JWST_VHS1256b_Reduction/tree/main/reduced_spectra

International audience

(abridged) Context. The origin of hot exozodiacal dust and its connection with outer dust reservoirs remains unclear. Aims. We aim to explore the possible connection between hot exozodiacal dust and warm dust reservoirs (> 100 K) in asteroid belts. Methods. We use precision near-infrared interferometry with VLTI/PIONIER to search for resolved emission at H band around a selected sample of nearby stars. Results. Our observations reveal the presence of resolved near-infrared emission around 17 out of 52 stars, four of which are shown to be due to a previously unknown stellar companion. The 13 other H-band excesses are thought to originate from the thermal emission of hot dust grains. Taking into account earlier PIONIER observations, and after reevaluating the warm dust content of all our PIONIER targets through spectral energy distribution modeling, we find a detection rate of 17.1(+8.1)(-4.6)% for H-band excess around main sequence stars hosting warm dust belts, which is statistically compatible with the occurrence rate of 14.6(+4.3)(-2.8)% found around stars showing no signs of warm dust. After correcting for the sensitivity loss due to partly unresolved hot disks, under the assumption that they are arranged in a thin ring around their sublimation radius, we however find tentative evidence at the 3{\sigma} level that H-band excesses around stars with outer dust reservoirs (warm or cold) could be statistically larger than H-band excesses around stars with no detectable outer dust. Conclusions. Our observations do not suggest a direct connection between warm and hot dust populations, at the sensitivity level of the considered instruments, although they bring to light a possible correlation between the level of H-band excesses and the presence of outer dust reservoirs in general., Comment: Accepted for publication in A&A

Tidal encounters in star clusters perturb discs around young protostars. In Cuello et al. (2019a, Paper I) we detailed the dynamical signatures of a stellar flyby in both gas and dust. Flybys produce warped discs, spirals with evolving pitch angles, increasing accretion rates, and disc truncation. Here we present the corresponding observational signatures of these features in optical/near-infrared scattered light and (sub-) millimeter continuum and CO line emission. Using representative prograde and retrograde encounters for direct comparison, we post-process hydrodynamical simulations with radiative transfer methods to generate a catalogue of multi-wavelength observations. This provides a reference to identify flybys in recent near-infrared and sub-millimetre observations (e.g., RW Aur, AS 205, HV Tau & DO Tau, FU Ori, V2775 Ori, and Z CMa)., 11 pages, 5 figures, accepted for publication in MNRAS

Understanding how giant planets form requires observational input from directly imaged protoplanets. We used VLT/NACO and VLT/SPHERE to search for companions in the transition disc of 2MASS J19005804-3645048 (hereafter CrA-9), an accreting M0.75 dwarf with an estimated age of 1-2 Myr. We found a faint point source at $\sim$0.7'' separation from CrA-9 ($\sim$108 au projected separation). Our 3-epoch astrometry rejects a fixed background star with a $5\sigma$ significance. The near-IR absolute magnitudes of the object point towards a planetary-mass companion. However, our analysis of the 1.0-3.8$\mu$m spectrum extracted for the companion suggests it is a young M5.5 dwarf, based on both the 1.13-$\mu$m Na index and comparison with templates of the Montreal Spectral Library. The observed spectrum is best reproduced with high effective temperature ($3057^{+119}_{-36}$K) BT-DUSTY and BT-SETTL models, but the corresponding photometric radius required to match the measured flux is only $0.60^{+0.01}_{-0.04}$ Jovian radius. We discuss possible explanations to reconcile our measurements, including an M-dwarf companion obscured by an edge-on circum-secondary disc or the shock-heated part of the photosphere of an accreting protoplanet. Follow-up observations covering a larger wavelength range and/or at finer spectral resolution are required to discriminate these two scenarios., Comment: 24 pages, 14 figures, 4 tables, to be published in MNRAS

Aims.We aim to demonstrate that the presence and mass of an exoplanet can now be effectively derived from the astrometry of another exoplanet.Methods.We combined previous astrometry ofβPictoris b with a new set of observations from the GRAVITY interferometer. The orbital motion ofβPictoris b is fit using Markov chain Monte Carlo simulations in Jacobi coordinates. The inner planet,βPictoris c, was also reobserved at a separation of 96 mas, confirming the previous orbital estimations.Results.From the astrometry of planet b only, we can (i) detect the presence ofβPictoris c and (ii) constrain its mass to 10.04−3.10+4.53MJup. If one adds the astrometry ofβPictoris c, the mass is narrowed down to 9.15−1.06+1.08MJup. The inclusion of radial velocity measurements does not affect the orbital parameters significantly, but it does slightly decrease the mass estimate to 8.89−0.75+0.75MJup. With a semimajor axis of 2.68 ± 0.02 au, a period of 1221 ± 15 days, and an eccentricity of 0.32 ± 0.02, the orbital parameters ofβPictoris c are now constrained as precisely as those ofβPictoris b. The orbital configuration is compatible with a high-order mean-motion resonance (7:1). The impact of the resonance on the planets’ dynamics would then be negligible with respect to the secular perturbations, which might have played an important role in the eccentricity excitation of the outer planet.

Protoplanetary disks with large inner dust cavities are thought to host massive planetary or substellar companions. These disks show asymmetries and rings in the millimeter continuum, caused by dust trapping in pressure bumps, and potentially vortices or horseshoes. The origin of the asymmetries and their diversity remains unclear. We present a comprehensive study of 16 disks for which the gas surface density profile has been constrained by CO isotopologue data. We compare the azimuthal extents of the dust continuum profiles with the local gas surface density in each disk, and find that the asymmetries correspond to higher Stokes numbers or low gas surface density. We discuss which asymmetric structures can be explained by a horseshoe, a vortex or spiral density waves. Second, we reassess the gas gap radii from the $^{13}$CO maps, which are about a factor 2 smaller than the dust ring radii, suggesting that companions in these disks are in the brown dwarf mass regime ($\sim 15-50 M_{\rm Jup}$) or in the Super-Jovian mass regime ($\sim 3-15 M_{\rm Jup}$) on eccentric orbits. This is consistent with the estimates from contrast curves on companion mass limits. These curves rule out (sub)stellar companions ($q>$0.05) for the majority of the sample at the gap location, but it remains possible at even smaller radii. Third, we find that spiral arms in scattered light images are primarily detected around high luminosity stars with disks with wide gaps, which can be understood by the dependence of the spiral arm pitch angle on disk temperature and companion mass., 36 pages, 16 figures. Accepted by the Astronomical Journal. Version 2 has fixed Figure 11 for which the subplots got mixed up

New instruments such as the ALMA interferometer and SPHERE on VLT allowed to obtain a large number of high-resolution images of protoplanetary discs. In these images, substructures such as gaps and rings can be clearly resolved and appear to be very common (see eg. Andrews et al. 2018). A natural explanation for the origin of such structures is the dynamical interaction of the gas and dust in the disc with one or more planets embedded in the parental disc (e.g. Lin & Papaloizou 1979, Dipierro et al. 2015, Rosotti et al. 2017, ..). Detections of planets embedded in disks are rare (e.g. Quanz et al. 2013, Keppler et al. 2018) and are mostly related to giant planets at wide orbits. However, the observed structures can be due to the interaction between the disc and low-mass planets. Planet-disc interaction can be studied with a synergy between observational results, current theoretical model and numerical simulations. In particular, theoretical models can find “signatures” to spot the presence of planets in discs, such as dusty or gaseous features due to the presence of circumplanetary discs or accretion streams (Bae et al. 2019, Toci et al. 2020) to be compared with real observations (Isella et al. 2019). I will present an analysis of several 3D SPH numerical simulations devised to analyze planet-disc interaction in presence of two giant planets. I will then compare my results with two observed systems: (1) HD169142 (Fedele et al.2017, Perez et al. 2019), a well studied source with two prominent rings in dust and gas; (2) PDS 70, the first source where protoplanets have been directly observed (Keppler et al. 2018). We initialise the system containing two giant planets in the disc (hereafter planet b and planet c respectively), studying the initial conditions that lead to the formation of a cavity in the gas distribution and rings in the dust. I will present the results about the dynamics of these discs (gap width, ring size and shape, cavity shape) and the properties of the planets (Toci et al., ApJL 2020, Toci et al. 2020, in prep.). My results show that the presence of two giant planets in a 5:1 resonance can be responsible of a long-lived dust ring between them, while at the same time creating a large gas cavity. However, the dust ring is absent when the giant planets end up in a closer resonance (3:1 or 2:1). I will also show how important it is to consider the migration and the accretion of planets for modelling observational results. Indeed, the interaction between the planets and the disc can give signatures both in the dust and gas components, leading to detectable features. In particular, our results suggest that the spur in the observed 1.3 mm continuum images of Perez et al. 2019 can be due to the interaction between the inner giant and the inner dust ring (see Fig. 1 and Fig. 2). If so, the spur should move according to the orbital motion of the planet. This theoretical prediction will be testable in a few years with new ALMA observations. Similarly, in the case of PDS70, the structures observed in Keppler et al. 2018 and Isella et al. 2019 can be explained with an accretion stream from the disc to the planet and the presence of a dusty circumplanetary disc (see Fig. 3 and Fig. 4).

Recent high resolution and high fidelity observations of protoplanetary discs are showing us peculiar substructures such as spirals, gaps, rings and horseshoes. In particular recent surveys have shown that the majority of these discs are characterised by rings and gaps. What can we learn from these features? Are these discs hiding planets? I will present the results we have obtained in order to model one specific disc orbiting around DS Tau, an M-type star, in the Taurus star-forming region located at a distance of 159 pc. This disc is showing a wide gap (∼30 au) in the continuum at 1.3 mm (Long et al. 2018) and at 2.9 mm (Long et al. 2020) (left panels of Fig. 1). We performed 3D-hydrodynamical (PHANTOM, Price et al. 2018) and radiative transfer (MCFOST, Pinte et al. 2006, 2009) simulations in order to reproduce the observed gap shape at 1.3 mm. In this modeling, we assumed that the observed gap is carved by a planet between one and five Jupiter masses. We fit the shape of the radial intensity profile along the disc major axis varying the planet mass, the dust disc mass, and the evolution time of the system. In the central panels of Fig. 1 we show the synthetic images, that have been computed for our best fit model (performed on the 1.3 mm case) parameters: Mp=3.5 MJup, Mdust=9.6*10-5 Msun and t=145 orbits. The right panels compare radial cuts of the flux intensity profile along the disc major axis obtained from the synthetic image at 1.3 and 2.9 mm (top and bottom center panel of Fig. 1) with the ALMA data (top and bottom left panel). The left (blue) and right (red) side of the radial cut correspond to the left and right side of the disc major axis. Dot markers represent the data, while the models are in dashed lines. We also computed the CO-isotopologues channel maps for the best model fitting the dust continuum (see Fig. 2 for an example), in order to study the expected signature of the planet in the gas kinematics. We found that the planet mass fitting the ALMA image is 3.5 Mjup and that this planet would be able to produce a kink detectable by ALMA with a reasonable beam size and velocity resolution. Figure 1. First row: ALMA observation (left panel) and continuum mock image (center panel) of the DS Tau disc at 1.3 mm. The synthetic image has been computed for our best fit model Mp=3.5 MJup and Mdust=9.6*10-5 Msun). The Gaussian beam we take to convolve the full resolution image has been chosen to reproduce the observations reported by Long et al. (2018) and Long et al. (2020), respectively 0.14''x0.1'' and 0.13''x0.09''. In the 1.3 mm image we highlight in blue the left side of the major axis and in red the right side. Right panel shows the comparison between the left (blue) - right (red) side of the radial cut along the disc major axis for the data (dot marker) and the modeling (dashed line). Second row: Same as first row but for the 2.9 mm continuum image. Figure 2: Channel maps for C18O isotopologue with a velocity resolution of 0.2 km/s and a beam size of [30,40,50,70] mas (from left to right). The azimuthal position of the planet is φ=225°. We show two velocity channels, Δv=2.7 km/s, where a kink is visible, and the opposite one at Δv=-2.7 km/s.

Context.Methods used to detect giant exoplanets can be broadly divided into two categories: indirect and direct. Indirect methods are more sensitive to planets with a small orbital period, whereas direct detection is more sensitive to planets orbiting at a large distance from their host star. This dichotomy makes it difficult to combine the two techniques on a single target at once.Aims.Simultaneous measurements made by direct and indirect techniques offer the possibility of determining the mass and luminosity of planets and a method of testing formation models. Here, we aim to show how long-baseline interferometric observations guided by radial-velocity can be used in such a way.Methods.We observed the recently-discovered giant planetβPictoris c with GRAVITY, mounted on the Very Large Telescope Interferometer.Results.This study constitutes the first direct confirmation of a planet discovered through radial velocity. We find that the planet has a temperature ofT = 1250 ± 50 K and a dynamical mass ofM = 8.2 ± 0.8 MJup. At 18.5 ± 2.5 Myr, this putsβPic c close to a ‘hot start’ track, which is usually associated with formation via disk instability. Conversely, the planet orbits at a distance of 2.7 au, which is too close for disk instability to occur. The low apparent magnitude (MK = 14.3 ± 0.1) favours a core accretion scenario.Conclusions.We suggest that this apparent contradiction is a sign of hot core accretion, for example, due to the mass of the planetary core or the existence of a high-temperature accretion shock during formation.

Massive stars like company. However, low-mass companions have remained extremely difficult to detect at angular separations ($\rho$) smaller than 1" (~1000-3000 au considering typical distance to nearby massive stars) given the large brightness contrast between the companion and the central star. Constraints on the low-mass end of the companions mass-function for massive stars are however needed, for example to help distinguishing between various scenarios for the formation of massive stars. To obtain statistically significant constraint on the presence of low-mass companions beyond the typical detection limit of current surveys ($\Delta \mathrm{mag} \lesssim 5$ at $\rho \lesssim 1$"), we initiated a survey of O and Wolf-Rayet stars in the Carina region using the SPHERE coronagraphic instrument on the VLT. In this first paper, we aim to introduce the survey, to present the methodology and to demonstrate the capability of SPHERE for massive stars using the multiple system QZ~Car. High-contrast imaging techniques, such as angular- and spectral-differential imaging techniques as well as PSF-fitting, were applied to detect and measure the relative flux of companions in each spectral channel of the instrument. We detected 19 sources around the QZ~Car system with detection limits of 9~mag at $\rho > 200$~mas for IFS and as faint as 13~mag at $\rho$ > 1".8 for IRDIS (corresponding to sub-solar masses for potential companions). All but two are reported here for the first time. Based on this proof of concept, we showed that VLT/SPHERE allows us to reach the sub-solar mass regime of the companion mass function. This paves the way for this type of observation with a large sample of massive stars to provide novel constraints on the multiplicity of massive stars in a region of the parameter space that has remained inaccessible so far., Comment: Submitted and accepted by A&A. 17 pages, 10 figures

Recent mm-wavelength surveys performed with the Atacama Large Millimeter Array (ALMA) have revealed protoplanetary discs characterized by rings and gaps. A possible explanation for the origin of such rings is the tidal interaction with an unseen planetary companion. The protoplanetary disc around DS Tau shows a wide gap in the ALMA observation at 1.3 mm. We construct a hydrodynamical model for the dust continuum observed by ALMA assuming the observed gap is carved by a planet between one and five Jupiter masses. We fit the shape of the radial intensity profile along the disc major axis varying the planet mass, the dust disc mass, and the evolution time of the system. The best fitting model is obtained for a planet with $M_{\rm p}=3.5\,M_{\rm Jup}$ and a disc with $M_{\rm dust}= 9.6\cdot10^{-5}\,M_{\odot}$. Starting from this result, we also compute the expected signature of the planet in the gas kinematics, as traced by CO emission. We find that such a signature (in the form of a "kink" in the channel maps) could be observed by ALMA with a velocity resolution between $0.2-0.5\,\rm{kms}^{-1}$ and a beam size between 30 and 50 mas., 16 pages, 15 figures, accepted for publication on MNRAS

Spiral arms in protoplanetary discs are thought to be linked to the presence of companions. We test the hypothesis that the double spiral arm morphology observed in the transition disc MWC 758 can be generated by an $\approx 10$ M$_{\rm Jup}$ companion on an eccentric orbit internal to the spiral arms. Previous studies on MWC 758 have assumed an external companion. We compare simulated observations from three dimensional hydrodynamics simulations of disc-companion interaction to scattered light, infrared and CO molecular line observations, taking into account observational biases. The inner companion hypothesis is found to explain the double spiral arms, as well as several additional features seen in MWC 758 -- the arc in the northwest, substructures inside the spiral arms, the cavity in CO isotopologues, and the twist in the kinematics. Testable predictions include detection of fainter spiral structure, detection of a point source south-southeast of the primary, and proper motion of the spiral arms., Comment: 13 pages, 6 figures, resubmitted to MNRAS

We present $L^\prime$-band Keck/NIRC2 imaging and $H$-band Subaru/AO188+HiCIAO polarimetric observations of CQ Tau disk with a new spiral arm. Apart from the spiral feature our observations could not detect any companion candidates. We traced the spiral feature from the $r^2$-scaled HiCIAO polarimetric intensity image and the fitted result is used for forward modeling to reproduce the ADI-reduced NIRC2 image. We estimated the original surface brightness after throughput correction in $L^\prime$-band to be $\sim126$ mJy/arcsec$^2$ at most. We suggest that the grain temperature of the spiral may be heated up to $\sim$200 K in order to explain both of the $H$- and $L^{\prime}$-bands results. The $H$-band emission at the location of the spiral originates from the scattering from the disk surface while both scattering and thermal emission may contribute to the $L^{\prime}$-band emission. If the central star is only the light source of scattered light, the spiral emission at $L^\prime$-band should be thermal emission. If an inner disk also acts as the light source, the scattered light and the thermal emission may equally contribute to the $L^\prime$-band spiral structure., Comment: accepted for publication in AJ

We present results from a near-infrared (NIR) adaptive optics (AO) survey of pre-main-sequence stars in the Lupus Molecular Cloud with VLT/NACO to identify (sub)stellar companions down to $\sim$20 au separation and investigate the effects of multiplicity on circumstellar disc properties. We observe for the first time in the NIR with AO a total of 47 targets and complement our observations with archival data for another 58 objects previously observed with the same instrument. All 105 targets have millimetre ALMA data available, which provide constraints on disc masses and sizes. We identify a total of 13 multiple systems, including 11 doubles and 2 triples. In agreement with previous studies, we find that the most massive (M$_{\rm dust}$ $>$ 50 M$_{\oplus}$) and largest ($R_{\rm dust}>$ 70 au) discs are only seen around stars lacking visual companions (with separations of 20-4800 au) and that primaries tend to host more massive discs than secondaries. However, as recently shown in a very similar study of $>$200 PMS stars in the Ophiuchus Molecular Cloud, the distribution of disc masses and sizes are similar for single and multiple systems for M$_{\rm dust} < 50$ M$_{\oplus}$ and radii $R_{\rm dust}$20 au mostly affect discs in the upper 10$\%$ of the disc mass and size distributions., Comment: 11 pages, 15 figures, accepted for publication in MNRAS

Context. The mechanisms of planet formation are still under debate. We know little about how planets form, even if more than 4000 exoplanets have been detected to date. Recent investigations target the cot of newly born planets: the protoplanetary disk. At the first stages of their life, exoplanets still accrete material from the gas-rich disk in which they are embedded. Transitional disks are indeed disks that show peculiarities, such as gaps, spiral arms, and rings, which can be connected to the presence of substellar companions. Aims. To investigate what is responsible for these features, we selected all the known transitional disks in the solar neighborhood (, Astronomy & Astrophysics, 633, ISSN:0004-6361, ISSN:1432-0746

We report the discovery of a low-mass stellar companion around the young Herbig Be star MWC 297. We performed multi-epoch high-contrast imaging in the near infrared (NIR) with the Very Large Telescope (VLT)/Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument. The companion is found at projected separation of 244.7$\pm$13.2 au and a position angle of 176.4$\pm$0.1 deg. The large separation supports formation via gravitational instability. From the spectrum, we estimate a mass of 0.1-0.5 M$_{\odot}$, the range conveying uncertainties in the extinction of the companion and in evolutionary models at young ages. The orbit coincides with a gap in the dust disk inferred from the Spectral Energy Distribution (SED). The young age ($\lesssim$ 1 Myr) and mass ratio with the central star ($\sim 0.01$) makes the companion comparable to PDS 70~b, suggesting a relation between formation scenarios and disk dynamics., Comment: 4 figures

The disc surrounding PDS 70, with two directly imaged embedded giant planets, is an ideal laboratory to study planet-disc interaction. We present three-dimensional smoothed particle hydrodynamics simulations of the system. In our simulations, planets, which are free to migrate and accrete mass, end up in a locked resonant configuration that is dynamically stable. We show that features observed at infrared (scattered light) and millimetre (thermal continuum) wavelengths are naturally explained by the accretion stream onto the outer planet, without requiring a circumplanetary disc around planet c. We post-processed our near-infrared synthetic images in order to account for observational biases known to affect high-contrast images. Our successful reproduction of the observations indicates that planet-disc dynamical interactions alone are sufficient to explain the observations of PDS 70., 15 pages, 11 figures

We still do not understand how planets form, or why extra-solar planetary systems are so different from our own solar system. But the last few years have dramatically changed our view of the discs of gas and dust around young stars. Observations with the Atacama Large Millimeter/submillimeter Array (ALMA) and extreme adaptive-optics systems have revealed that most --- if not all --- discs contain substructure, including rings and gaps, spirals, azimuthal dust concentrations, and shadows cast by misaligned inner discs. These features have been interpreted as signatures of newborn protoplanets, but the exact origin is unknown. Here we report the kinematic detection of a few Jupiter-mass planet located in a gas and dust gap at 130 au in the disc surrounding the young star HD 97048. An embedded planet can explain both the disturbed Keplerian flow of the gas, detected in CO lines, and the gap detected in the dust disc at the same radius. While gaps appear to be a common feature in protoplanetary discs, we present a direct correspondence between a planet and a dust gap, indicating that at least some gaps are the result of planet-disc interactions., preprint Nature Astronomy, 4 figures, 1 table, 8 suplementary figures

Resolved ALMA and VLA observations indicate the existence of two dust traps in the protoplanetary disc MWC 758. By means of 2D gas+dust hydrodynamical simulations post-processed with 3D dust radiative transfer calculations, we show that the spirals in scattered light, the eccentric, asymmetric ring and the crescent-shaped structure in the (sub)millimetre can all be caused by two giant planets: a 1.5-Jupiter mass planet at 35 au (inside the spirals) and a 5-Jupiter mass planet at 140 au (outside the spirals). The outer planet forms a dust-trapping vortex at the inner edge of its gap (at ~85 au), and the continuum emission of this dust trap reproduces the ALMA and VLA observations well. The outer planet triggers several spiral arms which are similar to those observed in polarised scattered light. The inner planet also forms a vortex at the outer edge of its gap (at ~50 au), but it decays faster than the vortex induced by the outer planet, as a result of the disc's turbulent viscosity. The vortex decay can explain the eccentric inner ring seen with ALMA as well as the low signal and larger azimuthal spread of this dust trap in VLA observations. Finding the thermal and kinematic signatures of both giant planets could verify the proposed scenario., 18 pages, 8 figures, accepted for publication in MNRAS

The large crescents imaged by ALMA in transition disks suggest that azimuthal dust trapping concentrates the larger grains, but centimetre-wavelengths continuum observations are required to map the distribution of the largest observable grains. A previous detection at ~1cm of an unresolved clump along the outer ring of MWC758 (Clump1), and buried inside more extended sub-mm continuum, motivates followup VLA observations. Deep multiconfiguration integrations reveal the morphology of Clump 1 and additional cm-wave components which we characterize via comparison with a deconvolution of recent 342GHz data (~1mm). Clump1, which concentrates ~1/3 of the whole disk flux density at ~1cm, is resolved as a narrow arc with a deprojected aspect ratio Chi>5.6, and with half the azimuthal width than at 342 GHz. The spectral trends in the morphology of Clump1 are quantitatively consistent with the Lyra-Lin prescriptions for dust trapping in an anticyclonic vortex, provided with porous grains (f~0.2+-0.2) in a very elongated (Chi~14+-3) and cold (T~23+-2K) vortex. The same prescriptions constrain the turbulence parameter alpha and the gas surface density Sigma_g through log10( alpha x Sigma_g /g/cm2)~-2.3+-0.4, thus requiring values for Sigma_g larger than a factor of a few compared to that reported in the literature from the CO isotopologues, if alpha, Comment: accepted to MNRAS

We introduce the Ophiuchus DIsc Survey Employing ALMA (ODISEA), a project aiming to study the entire population of Spitzer-selected protoplanetary discs in the Ophiuchus Molecular Cloud (~300 objects) from both millimeter continuum and CO isotopologues data. Here we present 1.3 mm/230 GHz continuum images of 147 targets at 0.2" (28 au) resolution and a typical rms of 0.15 mJy. We detect a total of 133 discs, including the individual components of 11 binary systems and 1 triple system. Fifty-three of these discs are spatially resolved. We find clear substructures (inner cavities, rings, gaps, and/or spiral arms) in 8 of the sources and hints of such structures in another 4 discs. We construct the disc luminosity function for our targets and perform comparisons to other regions. A simple conversion between flux and dust mass (adopting standard assumptions) indicates that all discs detected at 1.3 mm are massive enough to form one or more rocky planets. In contrast, only ~50 discs (~1/3 of the sample) have enough mass in the form of dust to form the canonical 10 M_Earth core needed to trigger runaway gas accretion and the formation of gas giant planets, although the total mass of solids already incorporated into bodies larger than cm scales is mostly unconstrained. The distribution in continuum disc sizes in our sample is heavily weighted towards compact discs: most detected discs have radii < 15 au, while only 23 discs (~15% of the targets) have radii > 30 au., 19 pages, 13 figures. Accepted for publication by MNRAS

We test the hypothesis that the disc cavity in the `transition disc' Oph IRS 48 is carved by an unseen binary companion. We use 3D dust-gas smoothed-particle hydrodynamics simulations to demonstrate that marginally coupled dust grains concentrate in the gas over-density that forms in in the cavity around a low binary mass ratio binary. This produces high contrast ratio dust asymmetries at the cavity edge similar to those observed in the disc around IRS 48 and other transition discs. This structure was previously assumed to be a vortex. However, we show that the observed velocity map of IRS 48 displays a peculiar asymmetry that is not predicted by the vortex hypothesis. We show the unusual kinematics are naturally explained by the non-Keplerian flow of gas in an eccentric circumbinary cavity. We further show that perturbations observed in the isovelocity curves of IRS 48 may be explained as the product of the dynamical interaction between the companion and the disc. The presence of a $\sim$0.4 M$_{\odot}$ companion at a $\sim$10 au separation can qualitatively explain these observations. High spatial resolution line and continuum imaging should be able to confirm this hypothesis., Comment: 9 pages, 7 figures, accepted for publication in MNRAS

We present polarized light observations of the transitional disk around Sz 91 acquired with VLT/NaCo at $H$ (1.7$��$m) and $K_s$ (2.2$��$m) bands. We resolve the disk and detect polarized emission up to $\sim$0."5 ($\sim$80 au) along with a central cavity at both bands. We computed a radiative transfer model that accounts for the main characteristics of the polarized observations. We found that the emission is best explained by small, porous grains distributed in a disk with a $\sim$45 au cavity. Previous ALMA observations have revealed a large sub-mm cavity ($\sim$83 au) and extended gas emission from the innermost (, 14 pages, 8 figures, accepted for publication in MNRAS

Transition discs are prime targets to look for protoplanets and study planet-disc interactions. We present VLT/SINFONI observations of PDS~70, a transition disc with a recently claimed embedded protoplanet. We take advantage of the angular and spectral diversity present in our data for an optimal PSF modeling and subtraction using principal component analysis (PCA). We report the redetection of PDS 70 b, both the front and far side of the outer disc edge, and the detection of several extended features in the annular gap. We compare spectral differential imaging applied before (PCA-SADI), and after (PCA-ASDI) angular differential imaging. Our tests suggest that PCA-SADI better recovers extended features, while PCA-ASDI is more sensitive to point sources. We adapted the negative fake companion (NEGFC) technique to infer the astrometry of the companion, and derived $r = 193.5 \pm 4.9 \mathrm{mas}$ and PA = 158.7deg $\pm$ 3.0deg. We used both NEGFC and ANDROMEDA to infer the $K$-band spectro-photometry of the protoplanet, and found results consistent with recent VLT/SPHERE observations, except for their 2018/02 epoch measurement in the $K2$ filter. Finally, we derived an upper limit of $\dot{M_b} < 1.26 \times 10^{-7} \big[ \frac{5 M_{\rm Jup}}{M_b} \big] \big[ \frac{R_b}{R_{\rm Jup}}\big] M_{\rm Jup} $ yr$^{-1}$ for the accretion rate of the companion based on an adaptation of PCA-SADI/PCA-ASDI around the Br$\gamma$ line., Comment: 20 pages, 12 figures. This is a pre-copyedited, author-produced PDF of an article accepted for publication in MNRAS on 2019 April 29

We present Subaru/SCExAO+CHARIS broadband ($JHK$-band) integral field spectroscopy of HD 34700 A. CHARIS data recover HD 34700 A's disk ring and confirm multiple spirals discovered in Monnier et al. (2019). We set limits on substellar companions of $\sim12\ M_{\rm Jup}$ at $0\farcs3$ (in the ring gap) and $\sim5\ M_{\rm Jup}$ at $0\farcs75$ (outside the ring). The data reveal darkening effects on the ring and spiral, although we do not identify the origin of each feature such as shadows or physical features related to the outer spirals. Geometric albedoes converted from the surface brightness suggests a higher scale height and/or prominently abundant sub-micron dust at position angle between $\sim45^\circ$ and $90^\circ$. Spiral fitting resulted in very large pitch angles ($\sim30-50^\circ$) and a stellar flyby of HD 34700 B or infall from a possible envelope is perhaps a reasonable scenario to explain the large pitch angles., 17 pages, 14 figures, accepted for publication in ApJ

We present evidence for localised deviations from Keplerian rotation, i.e., velocity "kinks", in 8 of 18 circumstellar disks observed by the DSHARP program: DoAr 25, Elias 2-27, GW Lup, HD 143006, HD 163296, IM Lup, Sz 129 and WaOph 6. Most of the kinks are detected over a small range in both radial extent and velocity, suggesting a planetary origin, but for some of them foreground contamination prevents us from measuring their spatial and velocity extent. Because of the DSHARP limited spectral resolution and signal-to-noise in the 12CO J=2-1 line, as well as cloud contamination, the kinks are usually detected in only one spectral channel, and will require confirmation. The strongest circumstantial evidence for protoplanets in the absence of higher spectral resolution data and additional tracers is that, upon deprojection, we find that all of the candidate planets lie within a gap and/or at the end of a spiral detected in dust continuum emission. This suggests that a significant fraction of the dust gaps and spirals observed by ALMA in disks are caused by embedded protoplanets., Accepted for publication in ApJ letters, 10 pages, 3 figures

We present the most sensitive direct imaging and radial velocity (RV) exploration of $\epsilon$ Eridani to date. $\epsilon$ Eridani is an adolescent planetary system, reminiscent of the early Solar system. It is surrounded by a prominent and complex debris disk which is likely stirred by one or several gas giant exoplanets. The discovery of the RV signature of a giant exoplanet was announced 15 years ago, but has met with scrutiny due to possible confusion with stellar noise. We confirm the planet with a new compilation and analysis of precise RV data spanning 30 years, and combine it with upper limits from our direct imaging search, the most sensitive ever performed. The deep images were taken in the Ms band (4.7$\mu$m) with the vortex coronagraph recently installed in W.M. Keck Observatory's infrared camera NIRC2, which opens a sensitive window for planet searches around nearby adolescent systems. The RV data and direct imaging upper limit maps were combined in an innovative joint Bayesian analysis, providing new constraints on the mass and orbital parameters of the elusive planet. $\epsilon$ Eridani b has a mass of $0.78^{+0.38}_{-0.12}$ $M_{Jup}$ and is orbiting $\epsilon$ Eridani at about $3.48\pm 0.02$ AU with a period of $7.37 \pm 0.07$ years. The eccentricity of $\epsilon$ Eridani b's orbit is $0.07^{+0.06}_{-0.05}$, an order of magnitude smaller than early estimates and consistent with a circular orbit. We discuss our findings from the standpoint of planet-disk interactions and prospects for future detection and characterization with the James Webb Space Telescope., Comment: Accepted to AJ

We present observations of the nearby (D$\sim$100\,pc) Herbig star HD~163296 taken with the vortex coronograph at Keck/NIRC2 in the L' band (3.7~$\mu$m), to search for planetary mass companions in the ringed disc surrounding this pre-main sequence star. The images reveal an arc-like region of scattered light from the disc surface layers that is likely associated with the first bright ring detected with ALMA in the $\lambda$=1.3mm dust continuum at $\sim$65~au. We also detect a point-like source at $\sim$0\farcs5 projected separation in the North-East direction, close to the inner edge of the second gap in the millimetre images. Comparing the point source photometry with the atmospheric emission models of non-accreting giant planets, we obtain a mass of 6--7~M$_J$ for a putative protoplanet, assuming a system age of 5~Myr. Based on the contrast at a 95\% level of completeness calculated on the emission-free regions of our images, we set upper limits for the masses of giant planets of 8--15~M$_J$, 4.5--6.5~M$_J$ and 2.5-4.0~M$_J$ at the locations of the first, second and third gap in the millimetre dust continuum, respectively. Further deep, high resolution thermal IR imaging of the HD~163296 system are warranted, to confirm the presence and nature of the point source and to better understand the structure of the dust disc., Comment: 9 pages, 6 figures. Accepted by MNRAS

Since its first light at the VLT in 2012, the Annular Groove Phase Mask (AGPM) has been used to implement vortex coronagraphy into AO-assisted infrared cameras at two additional world-leading observatories: the Keck Observatory and the LBT. In this paper, we review the status of these endeavors, and briefly highlight the main scientific results obtained so far. We explore the performance of the AGPM vortex coronagraph as a function of instrumental constraints, and identify the main limitations to the sensitivity to faint, off-axis companions in high-contrast imaging. These limitations include the AGPM itself, non-common path aberrations, as well as the data processing pipeline; we briefly describe our on-going efforts to further improve these various aspects. Based on the lessons learned from the first five years of on-sky exploitation of the AGPM, we are now preparing its implementation in a new generation of high-contrast imaging instruments. We detail the specificities of these instruments, and how they will enable the full potential of vortex coronagraphy to be unleashed in the future. In particular, we explain how the AGPM will be used to hunt for planets in the habitable zone of alpha Centauri A and B with a refurbished, AO-assisted version of the VISIR mid-infrared camera at the VLT (aka the NEAR project), and how this project paves the way towards mid-infrared coronagraphy on the ELT with the METIS instrument. We also discuss future LM-band applications of the AGPM with VLT/ERIS, ELT/METIS, and with a proposed upgrade of Keck/NIRC2, as well as future applications at shorter wavelengths, such as a possible upgrade of VLT/SPHERE with a K-band AGPM.

The circumstellar disk of the Herbig Fe star HD 142527 is host to several remarkable features including a warped inner disk, a 120 au-wide annular gap, a prominent dust trap and several spiral arms. A low-mass companion, HD 142527 B, was also found orbiting the primary star at $\sim$14 au. This study aims to better characterize this companion, which could help explain its impact on the peculiar geometry of the disk. We observed the source with VLT/SINFONI in $H$+$K$ band in pupil-tracking mode. Data were post-processed with several algorithms based on angular differential imaging (ADI). HD 142527 B is conspicuously re-detected in most spectral channels, which enables us to extract the first medium-resolution spectrum of a low-mass companion within 0.1'' from its central star. Fitting our spectrum with both template and synthetic spectra suggests that the companion is a young M2.5$\pm$1.0 star with an effective temperature of $3500\pm100$ K, possibly surrounded with a hot (1700 K) circum-secondary environment. Pre-main sequence evolutionary tracks provide a mass estimate of $0.34\pm0.06 M_{\odot}$, independent of the presence of a hot environment. However, the estimated stellar radius and age do depend on that assumption; we find a radius of $1.37 \pm 0.05 R_{\odot}$ (resp. $1.96 \pm 0.10 R_{\odot}$) and an age of $1.8^{+1.2}_{-0.5}$ Myr (resp. $0.75 \pm 0.25$ Myr) in the case of the presence (resp. absence) of a hot environment contributing in $H$+$K$. Our new values for the mass and radius yield a mass accretion rate of $\sim$5 $\times 10^{-9} M_{\odot}$ yr$^{-1}$ (2-3% that of the primary). Our results illustrate thus the potential for SINFONI+ADI to characterize faint close-in companions. The new spectral type makes HD 142527 B a twin of the well known TW Hya T-Tauri star, and the revision of its mass to higher values further supports its role in shaping the disk., Accepted for publication in A&A. 21 pages, 11 figures, 4 tables, 2 appendices

We present 3D hydrodynamical models of the HD142527 protoplanetary disc, a bright and well studied disc that shows spirals and shadows in scattered light around a 100 au gas cavity, a large horseshoe dust structure in mm continuum emission, together with mysterious fast radial flows and streamers seen in gas kinematics. By considering several possible orbits consistent with the observed arc, we show that all of the main observational features can be explained by one mechanism - the interaction between the disc and the observed binary companion. We find that the spirals, shadows and horseshoe are only produced in the correct position angles by a companion on an inclined and eccentric orbit approaching periastron - the 'red' family from Lacour et al. (2016). Dust-gas simulations show radial and azimuthal concentration of dust around the cavity, consistent with the observed horseshoe. The success of this model in the HD142527 disc suggests other mm-bright transition discs showing cavities, spirals and dust asymmetries may also be explained by the interaction with central companions., 16 pages, 12 figures, accepted to MNRAS. Movies at http://users.monash.edu.au/~dprice/pubs/HD142527/

Transition disks offer the extraordinary opportunity to look for newly born planets and investigate the early stages of planet formation. In this context we observed the Herbig A5 star MWC 758 with the L band vector vortex coronagraph installed in the near-infrared camera and spectrograph NIRC2 at the Keck II telescope, with the aim of unveiling the nature of the spiral structure by constraining the presence of planetary companions in the system. Our high-contrast imaging observations show a bright (delta L=7.0+/-0.3 mag) point-like emission, south of MWC 758 at a deprojected separation of about 20 au (r=0.111+/- 0. 004 arcsec) from the central star. We also recover the two spiral arms (south-east and north-west), already imaged by previous studies in polarized light, and discover a third one to the south-west of the star. No additional companions were detected in the system down to 5 Jupiter masses beyond 0.6 arcsec from the star. We propose that the bright L band emission could be caused by the presence of an embedded and accreting protoplanet, although the possibility of it being an asymmetric disk feature cannot be excluded. The spiral structure is probably not related to the protoplanet candidate, unless on an inclined and eccentric orbit, and it could be due to one (or more) yet undetected planetary companions at the edge of or outside the spiral pattern. Future observations and additional simulations will be needed to shed light on the true nature of the point-like source and its link with the spiral arms., Comment: 10 pages, 9 figures, Accepted for publication in Astronomy & Astrophysics