arXiv subjects

Mark Wyatt

Publications and source records attributed to Mark Wyatt.

At least 19 recordsLinked to original sources

arXiv2026

A radially broad collisional cascade in the debris disk of $\gamma$ Ophiuchi observed by JWST

The A1V star $\gamma$ Oph, at a distance of 29.7 pc, is known from Spitzer imaging to host a debris disk with a large radial extent and from its spectral energy distribution to host inner warm dust. We imaged $\gamma$ Oph with JWST/MIRI at 15 and 25.5 $\mu$m, revealing smooth and radially broad emission that extends to a radius of at least 250 au at 25.5 $\mu$m. In contrast to JWST findings of an inner small-grain component with distinct ringed structures in Fomalhaut and Vega, the mid-infrared radial profile combined with prior ALMA imaging suggests a radially broad steady-state collisional cascade with the same grain size distribution throughout the disk. This further suggests that the system is populated by a radially broad planetesimal belt from tens of au or less to well over 200 au, rather than a narrow planetesimal belt from which the observed dust is displaced to appear broad. The disk is also found to be asymmetric, which could be modelled by a stellocentric offset corresponding to a small eccentricity of $\sim$0.03. Such a disk eccentricity could be induced by a mildly eccentric $<10\,M_\mathrm{Jup}$ giant planet outside 10 au, or a more eccentric companion up to stellar mass at a few au, without producing a resolvable radial gap in the disk.

astro-ph.EP↗

arXiv2025

The SPace-based InterFerometer Feasibility (SPIFF) Project: Enabling Future High-Resolution Astronomy Across the EM Spectrum

A plethora of astronomical science cases can only be achieved with high angular resolution observations, and we can expect the number of these to grow as astronomers are constrained by the size limitations of single-aperture space telescopes, making space-based interferometry inevitable. However, the enabling technologies do not have flight heritage at the system level, and the concept remains immature to much of the community, meaning no direct-detection synthetic-aperture space-based interferometer has yet flown and an opportunity exists for the UK to take a world leading role. Here we propose the SPace-based InterFerometry Feasibility (SPIFF) Project as a program to address both issues simultaneously by: 1) completing a thorough survey of the science cases across the EM spectrum that would directly benefit from, or be impossible without, space-based interferometry; 2) down selecting key requirements via a Science Traceability Matrix mapping exercise; 3) host a workshop for the UK astronomical community to consolidate these findings; 4) build a technology demonstration mission to raise TRL and achieve flight heritage of critical technologies. Such a program positions the UK as the partner of choice for any future NASA or ESA space-based interferometry mission, allowing the UK to lead groundbreaking scientific discoveries, while also directly benefiting the UK industrial base by advancing domestic exportable technologies and building direct synergy with other UK space priorities. Indeed, the UK is uniquely positioned to lead in space-based interferometry, possessing a rare trifecta of domestic strengths: world-class expertise in ground-based interferometry and space-based instrumentation; commercial entities developing mission-critical technologies; and scientists whose research spans the full range of science cases that would benefit directly from space-based interferometry.

astro-ph.IM↗

arXiv2025

Re-accretion of Giant Impact Ejecta Can Drive Significant Atmospheric Erosion on Terrestrial Planets

Giant impacts, the collisions between planetary embryos, play a crucial role in sculpting the planets and their orbital architectures. Numerical simulations have advanced our understanding of these events, enabling estimations of mass and atmospheric loss during the primary impacts. However, high computational costs have restricted investigations to the immediate aftermath, limiting our understanding of the longer-term consequences. In this study, we investigate the effect of re-accretion of giant impact debris, a process previously overlooked, on the atmospheres of terrestrial planets. Following the collisional and dynamical evolution of the debris ejected during the primary impacts, we quantify the amount of debris that would be re-accreted by the progenitor. We find that $\sim 0.003\ M_{\oplus}$ would be re-accreted over a wide range of Earth-like planet properties, assuming $1\%$ of their mass is ejected as non-vaporised debris. Over a prolonged period, the secondary impacts during re-accretion drive enhanced atmospheric loss. Notably, the impacts from the debris of the canonical Moon-forming impact would have gradually eroded an atmosphere similar to present-day Earth's in $\sim 30$ Myr. More generally, any planet growing via giant impacts within $2$ au is likely to experience significant post-impact atmospheric erosion unless the initial atmosphere was at least $5$ times more massive than Earth's. Our results highlight the crucial role secondary impacts from giant-impact ejecta could have in driving the long-term atmospheric evolution of Earth-like planets, and demonstrate that giant impacts can be significantly more effective at eroding such atmospheres than previously thought, when re-accretion of debris is considered.

astro-ph.EP↗

arXiv2025

High Resolution ALMA Data of the Fomalhaut Debris Disk Confirms Apsidal Width Variation

We present long-baseline observations of the Fomalhaut outer debris disk at 223 GHz (1.3 mm) from ALMA Cycle 5, which we use along with archival short-baseline observations to produce a 0".57 resolution mosaic of the disk at a sensitivity of 7 $\mu$Jy/bm. We use radial profiles to measure the disk at the ansae and find that the southeast (SE) side of the disk is 4 AU wider than the northwest (NW) side as observed by ALMA. We also find that the peak brightness of the NW ansa is $21\pm1\%$ brighter than the SE ansa. We perform MCMC fits of the ALMA visibilities using two analytical, eccentric disk models. Our results suggest that the model including a dispersion parameter for the proper eccentricity ($\sigma_{e_p}$), which accounts for additional scatter in the eccentricity of individual orbits, is preferred over the model without one. Such a model implies that self-gravitation, particle collisions, and close-packing could play a role in shaping the overall structure of the Fomalhaut disk as is seen in eccentric planetary rings. Crucially, neither model can reproduce the brightness or width asymmetry near the NW ansa. No emission from the Intermediate Belt is detected, allowing us to place a 3-$\sigma$ upper limit of 396 $\mu$Jy at 1.3 mm. We also discover a spectral line in archival Cycle 3 data centered at $\nu_{\rm obs}\approx230.25$ GHz at the location of the ``Great Dust Cloud," whose redshift from the expected CO line for Fomalhaut confirms the source is a background galaxy.

astro-ph.EP↗

arXiv2025

Worlds Next Door: A Candidate Giant Planet Imaged in the Habitable Zone of $\alpha$ Cen A. II. Binary Star Modeling, Planet and Exozodi Search, and Sensitivity Analysis

JWST observed our closest solar twin, $\alpha$ Cen A, with the MIRI coronagraph in F1550C (15.5 $\mu$m) at three distinct epochs between August 2024 and April 2025. For the first time with JWST, we demonstrate the application of reference star differential imaging to simultaneously subtract the coronagraphic image of a primary star and the point spread function (PSF) of its binary companion to conduct a deep search for exoplanets and dust emission. We achieve a typical 5$\sigma$ point source contrast sensitivity between $\sim$$10^{-5}$-$10^{-4}$ at separations $\gtrsim$ 1" and an exozodiacal disk (coplanar with $\alpha$ Cen AB) sensitivity of $\sim$5-8$\times$ the Solar System's zodiacal cloud around $\alpha$ Cen A. The latter is an extraordinary limit, representing the deepest sensitivity to exozodiacal disks achieved for any stellar system to date. Post-processing with the PCA-KLIP algorithm reveals a point source, called $S1$, in August 2024, detected at S/N $=$ 4-6 (3.3-4.3$\sigma$), a separation of $\approx$1.5" (2 au), and with a F1550C flux (contrast) of $\approx$3.5 mJy ($\approx 5.5 \times 10^{-5}$). Various tests conducted with the data show that $S1$ is unlikely to be a detector or PSF subtraction artifact and confirm that it is neither a background nor a foreground object. $S1$ is not re-detected in the two follow-up observations (February and April 2025). If $S1$ is astrophysical in nature, the only explanation is that it has moved to a region of poor sensitivity due to orbital motion. We perform PSF injection-recovery tests and provide 2D sensitivity maps for each epoch to enable orbital completeness calculations. Additional observations are necessary to re-detect candidate $S1$ and confirm its nature as a planet orbiting our nearest solar-type neighbor.

astro-ph.EP↗

arXiv2025

Worlds Next Door: A Candidate Giant Planet Imaged in the Habitable Zone of $\alpha$ Cen A. I. Observations, Orbital and Physical Properties, and Exozodi Upper Limits

We report on coronagraphic observations of the nearest solar-type star, $\alpha$ Cen A, using the MIRI instrument on the James Webb Space Telescope. With three epochs of observation (August 2024, February 2025, and April 2025), we achieve a sensitivity sufficient to detect $T_{\rm eff}\approx$ 225-250 K (1-1.2 $R_{\rm Jup}$) planets between 1"-2" and exozodiacal dust emission at the level of $>$5-8$\times$ the brightness of our own zodiacal cloud. The lack of exozodiacal dust emission sets an unprecedented limit of a few times the brightness of our own zodiacal cloud$-$a factor of $\gtrsim$10 more sensitive than measured toward any other stellar system to date. In August 2024, we detected a F$_\nu$(15.5 $\mu$m) = 3.5 mJy point source, called $S1$, at a separation of 1.5" from $\alpha$ Cen A. Because the August 2024 epoch had only one successful observation at a single roll angle, it is not possible to unambiguously confirm $S1$ as a bona fide planet. Our analysis confirms that $S1$ is neither a background nor a foreground object. $S1$ is not recovered in the February and April 2025 epochs. However, if $S1$ is the counterpart of the object, $C1$, seen by the VLT/NEAR program in 2019, we find that there is a 52% chance that the $S1+C1$ candidate was missed in both follow-up JWST/MIRI observations due to orbital motion. Incorporating constraints from the non-detections, we obtain families of dynamically stable orbits for $S1+C1$ with periods between 2-3 years. These suggest that the planet candidate is on an eccentric ($e \approx 0.4$) orbit significantly inclined with respect to $\alpha$ Cen AB orbital plane ($i_{\rm mutual} \approx 50^\circ$, or $\approx 130^\circ$). Based on the photometry and orbital properties, the planet candidate could have a temperature of 225 K, a radius of $\approx$1-1.1 $R_{\rm Jup}$ and a mass between 90-150 $M_{\rm Earth}$, consistent with RV limits.

astro-ph.EP↗

arXiv2025

Exozodiacal dust as a limitation to exoplanet imaging and spectroscopy

In addition to planets and other small bodies, stellar systems will likely also host exozodiacal dust, or exozodi. This warm dust primarily resides in or near the habitable zone of a star, and scatters stellar light in visible to NIR wavelengths, possibly acting as a spatially inhomogeneous fog that can impede our ability to detect and characterize Earth-like exoplanets. By improving our knowledge of exozodi in the near term with strategic precursor observations and model development, we may be able to mitigate these effects to support a future search for signs of habitability and life with a direct imaging mission. This white paper introduces exozodi, summarizes its impact on directly imaging Earth-like exoplanets, and outlines several key knowledge gaps and near-term solutions to maximize the science return of future observations.

astro-ph.IM↗

arXiv2025

A PR drag origin for the Fomalhaut disk's pervasive inner dust: constraints on collisional strengths, icy composition, and embedded planets

Recent JWST observations of the Fomalhaut debris disk have revealed a significant abundance of dust interior to the outer planetesimal belt, raising questions about its origin and maintenance. In this study, we apply an analytical model to the Fomalhaut system, that simulates the dust distribution interior to a planetesimal belt, as collisional fragments across a range of sizes are dragged inward under Poynting-Robertson (PR) drag. We generate spectral energy distributions and synthetic JWST/MIRI images of the model disks, and perform an extensive grid search for particle parameters -- pertaining to composition and collisional strength -- that best match the observations. We find that a sound fit can be found for particle properties that involve a substantial water ice component, around 50%--80% by total volume, and a catastrophic disruption threshold, $Q_D^\star$, at a particle size of $D\!\approx\!30\,$um of 2--4$\,\times\,10^6\,$erg/g. Based on the expected dynamical depletion of migrating dust by an intervening planet we discount planets with masses $>1\,M_\mathrm{Saturn}$ beyond $\sim50\,$au in the extended disk, though a planet shepherding the inner edge of the outer belt of up to $\sim2\,M_\mathrm{Saturn}$ is reconcilable with the PR-drag-maintained disk scenario, contingent upon higher collisional strengths. These results indicate that PR drag transport from the outer belt alone can account for the high interior dust contents seen in the Fomalhaut system, which may thus constitute a common phenomenon in other belt-bearing systems. This establishes a framework for interpreting mid-planetary system dust around other stars, with our results for Fomalhaut providing a valuable calibration of the models.

astro-ph.EP↗

arXiv2024

A JWST MIRI MRS View of the $η$ Tel Debris Disk and its Brown Dwarf Companion

We report JWST MIRI MRS observations of the $β$ Pictoris moving group member, $η$ Telescopii ($η$ Tel) A and its brown dwarf binary companion, $η$ Tel B. Following PSF subtraction, we recover the spatially resolved flux from the debris disk around $η$ Tel A, along with the position of the companion exterior to the disk. We present a new 5-26 $μ$m epoch of spectroscopy for the disk, in which we discover a 20 $μ$m silicate feature. We also present the first ever 11-21 $μ$m spectrum of $η$ Tel B, which indicates a bare photosphere. We derive a new epoch of relative astrometry for the companion, extending the baseline of measurements to 25 years, and find that its current location is consistent with the apocentre of an eccentric, long-period orbit. The companion's orbit is close enough to the disk that it should significantly perturb the planetesimals within it, resulting in a detectable mid-IR pericentre glow and near-alignment with the companion. Contrary to expectations, however, we find that the disk appears to be axisymmetric and potentially misaligned with the companion in the MIRI MRS data. We posit that this may be due to the presence of an additional, yet-undetected 0.7-30 $M_J$ planet orbiting interior to the disk with a semi-major axis of 3-19 au.

astro-ph.EP↗

arXiv2024

Cosmic dust fertilization of glacial prebiotic chemistry on early Earth

Earth's surface is deficient in available forms of many elements considered limiting for prebiotic chemistry. In contrast, many extraterrestrial rocky objects are rich in these same elements. Limiting prebiotic ingredients may, therefore, have been delivered by exogenous material; however, the mechanisms by which exogeneous material may be reliably and non-destructively supplied to a planetary surface remains unclear. Today, the flux of extraterrestrial matter to Earth is dominated by fine-grained cosmic dust. Although this material is rarely discussed in a prebiotic context due to its delivery over a large surface area, concentrated cosmic dust deposits are known to form on Earth today due to the action of sedimentary processes. Here we combine empirical constraints on dust sedimentation with dynamical simulations of dust formation and planetary accretion to show that localized sedimentary deposits of cosmic dust could have accumulated in arid environments on early Earth, in particular glacial settings that today produce cryoconite sediments. Our results challenge the widely held assumption that cosmic dust is incapable of fertilizing prebiotic chemistry. Cosmic dust deposits may have plausibly formed on early Earth and acted to fertilize prebiotic chemistry.

astro-ph.EP↗

arXiv2023

The debris disc of HD 131488 -- Bringing together thermal emission and scattered light

We show the first SPHERE/IRDIS and IFS data of the CO-rich debris disc around HD 131488. We use N-body simulations to model both the scattered light images and the SED of the disc in a self-consistent way. We apply the Henyey-Greenstein approximation, Mie theory, and the Discrete Dipole Approximation to model the emission of individual dust grains. Our study shows that only when gas drag is taken into account can we find a model that is consistent with scattered light as well as thermal emission data of the disc. The models suggest a gas surface density of $2\times10^{-5}\,M_\oplus/$au$^2$ which is in agreement with estimates from ALMA observations. Thus, our modelling procedure allows us to roughly constrain the expected amount of gas in a debris disc without actual gas measurements. We also show that the shallow size distribution of the dust leads to a significant contribution of large particles to the overall amount of scattered light. The scattering phase function indicates a dust porosity of $\sim0.2\ldots 0.6$ which is in agreement with a pebble pile scenario for planetesimal growth.

astro-ph.EP↗

arXiv2023

Planetary system architectures with low-mass inner planets: Direct imaging exploration of mature systems beyond 1 au

The discovery of planets orbiting at less than 1 au from their host star and less massive than Saturn in various exoplanetary systems revolutionized our theories of planetary formation. The fundamental question is whether these close-in low-mass planets could have formed in the inner disk interior to 1 au, or whether they formed further out in the planet-forming disk and migrated inward. Exploring the role of additional giant planets in these systems may help us to pinpoint their global formation and evolution. We searched for additional substellar companions by using direct imaging in systems known to host close-in small planets. The use of direct imaging complemented by radial velocity and astrometric detection limits enabled us to explore the giant planet and brown dwarf demographics around these hosts to investigate the potential connection between both populations. We carried out a direct imaging survey with VLT/SPHERE to look for outer giant planets and brown dwarf companions in 27 systems hosting close-in low-mass planets discovered by radial velocity. Our sample is composed of very nearby (<20pc) planetary systems, orbiting G-, K-, and M-type mature (0.5-10Gyr) stellar hosts. We performed homogeneous direct imaging data reduction and analysis to search for and characterize point sources, and derived robust statistical detection limits. Of 337 point-source detections, we do not find any new bound companions. We recovered the emblematic very cool T-type brown dwarf GJ229B. Our typical sensitivities in direct imaging range from 5 to 30 MJup beyond 2 au. The non-detection of massive companions is consistent with predictions based on models of planet formation by core accretion. Our pilot study opens the way to a multi-technique approach for the exploration of very nearby exoplanetary systems with future ground-based and space observatories.

astro-ph.EP↗

arXiv2022

ALMA Observations of the HD~110058 debris disk

We present Atacama Large Millimeter Array (ALMA) observations of the young, gas-rich debris disk around HD110058 at 0.3-0.6\arcsec resolution. The disk is detected in the 0.85 and 1.3~mm continuum, as well as in the J=2-1 and J=3-2 transitions of $^{12}$CO and $^{13}$CO. The observations resolve the dust and gas distributions and reveal that this is the smallest debris disk around stars of similar luminosity observed by ALMA. The new ALMA data confirm the disk is very close to edge-on, as shown previously in scattered light images. We use radiative transfer modeling to constrain the physical properties of dust and gas disks. The dust density peaks at around 31~au and has a smooth outer edge that extends out to $\sim70$~au. Interestingly, the dust emission is marginally resolved along the minor axis, which indicates that it is vertically thick if truly close to edge-on with an aspect ratio between 0.13 and 0.28. We also find that the CO gas distribution is more compact than the dust \ah{(similarly to the disk around 49 Ceti)}, which could be due to a low viscosity and a higher gas release rate at small radii. Using simulations of the gas evolution taking into account the CO photodissociation, shielding, and viscous evolution, we find that HD~110058's CO gas mass and distribution are consistent with a secondary origin scenario. Finally, we find that the gas densities may be high enough to cause the outward drift of small dust grains in the disk.

astro-ph.SR↗

arXiv2022

The JWST Early Release Science Program for the Direct Imaging & Spectroscopy of Exoplanetary Systems

The direct characterization of exoplanetary systems with high contrast imaging is among the highest priorities for the broader exoplanet community. As large space missions will be necessary for detecting and characterizing exo-Earth twins, developing the techniques and technology for direct imaging of exoplanets is a driving focus for the community. For the first time, JWST will directly observe extrasolar planets at mid-infrared wavelengths beyond 5$μ$m, deliver detailed spectroscopy revealing much more precise chemical abundances and atmospheric conditions, and provide sensitivity to analogs of our solar system ice-giant planets at wide orbital separations, an entirely new class of exoplanet. However, in order to maximise the scientific output over the lifetime of the mission, an exquisite understanding of the instrumental performance of JWST is needed as early in the mission as possible. In this paper, we describe our 55-hour Early Release Science Program that will utilize all four JWST instruments to extend the characterisation of planetary mass companions to $\sim$15$μ$m as well as image a circumstellar disk in the mid-infrared with unprecedented sensitivity. Our program will also assess the performance of the observatory in the key modes expected to be commonly used for exoplanet direct imaging and spectroscopy, optimize data calibration and processing, and generate representative datasets that will enable a broad user base to effectively plan for general observing programs in future cycles.

astro-ph.EP↗

arXiv2021

Atmospheric characterization of terrestrial exoplanets in the mid-infrared: biosignatures, habitability & diversity

Exoplanet science is one of the most thriving fields of modern astrophysics. A major goal is the atmospheric characterization of dozens of small, terrestrial exoplanets in order to search for signatures in their atmospheres that indicate biological activity, assess their ability to provide conditions for life as we know it, and investigate their expected atmospheric diversity. None of the currently adopted projects or missions, from ground or in space, can address these goals. In this White Paper we argue that a large space-based mission designed to detect and investigate thermal emission spectra of terrestrial exoplanets in the MIR wavelength range provides unique scientific potential to address these goals and surpasses the capabilities of other approaches. While NASA might be focusing on large missions that aim to detect terrestrial planets in reflected light, ESA has the opportunity to take leadership and spearhead the development of a large MIR exoplanet mission within the scope of the "Voyage 2050" long-term plan establishing Europe at the forefront of exoplanet science for decades to come. Given the ambitious science goals of such a mission, additional international partners might be interested in participating and contributing to a roadmap that, in the long run, leads to a successful implementation. A new, dedicated development program funded by ESA to help reduce development and implementation cost and further push some of the required key technologies would be a first important step in this direction. Ultimately, a large MIR exoplanet imaging mission will be needed to help answer one of mankind's most fundamental questions: "How unique is our Earth?"

astro-ph.EP↗

arXiv2021

Discovery of an Edge-on Circumstellar Debris Disk Around BD+45$^{\circ}$598: a Newly Identifed Member of the $β$ Pictoris Moving Group

We report the discovery of a circumstellar debris disk viewed nearly edge-on and associated with the young, K1 star BD+45$^{\circ}$598 using high-contrast imaging at 2.2$μ$m obtained at the W.M.~Keck Observatory. We detect the disk in scattered light with a peak significance of $\sim$5$σ$ over three epochs, and our best-fit model of the disk is an almost edge-on $\sim$70 AU ring, with inclination angle $\sim$87$^\circ$. Using the NOEMA interferometer at the Plateau de Bure Observatory operating at 1.3mm, we find resolved continuum emission aligned with the ring structure seen in the 2.2$μ$m images. We estimate a fractional infrared luminosity of $L_{IR}/L_{tot}$ $\simeq6^{+2}_{-1}$$\times$$10^{-4}$, higher than that of the debris disk around AU Mic. Several characteristics of BD+45$^{\circ}$598, such as its galactic space motion, placement in a color-magnitude diagram, and strong presence of Lithium, are all consistent with its membership in the $β$ Pictoris Moving Group with an age of 23$\pm$3 Myr. However, the galactic position for BD+45$^{\circ}$598 is slightly discrepant from previously-known members of the $β$ Pictoris Moving Group, possibly indicating an extension of members of this moving group to distances of at least 70pc. BD+45$^{\circ}$598 appears to be an example from a population of young circumstellar debris systems associated with newly identified members of young moving groups that can be imaged in scattered light, key objects for mapping out the early evolution of planetary systems from $\sim$10-100 Myr. This target will also be ideal for northern-hemisphere, high-contrast imaging platforms to search for self-luminous, planetary mass companions residing in this system.

astro-ph.EP↗

arXiv2021

A $~75\%$ Occurrence Rate of Debris Discs around F stars in the $β$ Pic Moving Group

Only 20\% of old field stars have detectable debris discs, leaving open the question of what disc, if any, is present around the remaining 80\%. Young moving groups allow to probe this population, since discs are expected to have been brighter early on. This paper considers the population of F~stars in the 23~Myr-old BPMG where we find that 9/12 targets possess discs. We also analyse archival ALMA data to derive radii for 4 of the discs, presenting the first image of the 63au radius disc of HD~164249. Comparing the BPMG results to disc samples from $\sim45$~Myr and $\sim150$~Myr-old moving~groups, and to discs found around field stars, we find the disc incidence rate in young moving~groups is comparable to that of the BPMG and significantly higher than that of field~stars. The BPMG discs tend to be smaller than those around field~stars. However, this difference is not statistically significant due to the small number of targets. Yet, by analysing the fractional luminosity vs disc radius parameter space we find that the fractional luminosities in the populations considered drop by two orders of magnitude within the first 100~Myr. This is much faster than expected by collisional evolution, implying a decay equivalent to $1/\text{age}^2$. We attribute this depletion to embedded planets which would be around 170~$M_\text{earth}$ to cause a depletion on the appropriate timescale. However, we cannot rule out that different birth environments of nearby young clusters result in brighter debris discs than the progenitors of field~stars which likely formed in a more dense environment.

astro-ph.EP↗

arXiv2020

The effect of stellar multiplicity on protoplanetary discs. A NIR survey of the Lupus star forming region

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 $R_{\rm dust}<$ 70 au. Such discs correspond to $\sim $80-90\% of the sample. This result can be seen in the combined sample of Lupus and Ophiuchus objects, which now includes more than 300 targets with ALMA imaging and NIR AO data, and implies that stellar companions with separations $>$20 au mostly affect discs in the upper 10$\%$ of the disc mass and size distributions.

astro-ph.EP↗