arXiv subjects

J. P. Marshall

Publications and source records attributed to J. P. Marshall.

At least 19 recordsLinked to original sources

arXiv2026

The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) V: Comparison between scattered light and thermal emission

Debris discs are analogues to our own Kuiper belt around main-sequence stars and are therefore referred to as exoKuiper belts. They have been resolved at high angular resolution at wavelengths spanning the optical to the submillimetre-millimetre regime. Short wavelengths probe the light scattered by such discs, which is dominated by micron-sized dust particles, while millimetre wavelengths probe the thermal emission of millimetre-sized particles. Determining differences in the dust distribution between millimetre- and micron-sized dust is fundamental to revealing the dynamical processes affecting the dust in debris discs. We aim to compare the scattered light from the discs of the ALMA survey to Resolve exoKuiper belt Substructures (ARKS) with the thermal emission probed by ALMA. We focus on the radial distribution of the dust. We used high-contrast scattered light observations obtained with VLT/SPHERE, GPI, and the HST to uniformly study the dust distribution in those systems and compare it to the dust distribution extracted from the ALMA observations carried out in the course of the ARKS project. We also set constraints on the presence of planets by using these high-contrast images combined with exoplanet evolutionary models. 15 of the 24 discs comprising the ARKS sample are detected in scattered light, with TYC9340-437-1 being imaged for the first time at near-infrared wavelengths. For 6 of those 15 discs, the dust surface density seen in scattered light peaks farther out compared to that observed with ALMA. These 6 discs except one are known to also host cold CO gas. Conversely, the systems without significant offsets are not known to host gas, except one. This observational study suggests that the presence of gas in debris discs may affect the small and large grains differently, pushing the small dust to greater distances where the gas is less abundant.

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arXiv2026

The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) I: Motivation, sample, data reduction, and results overview

The outer regions of planetary systems host dusty debris discs analogous to the Kuiper belt (exoKuiper belts), which provide crucial constraints on planet formation and evolution processes. ALMA dust observations have revealed a great diversity, and that some belts contain CO gas, whose origin and implications are uncertain. Most of this progress, however, has been limited by low-resolution observations. We conducted the first ALMA large programme dedicated to debris discs: the ALMA survey to Resolve exoKuiper belt Substructures (ARKS). We selected the 24 most promising belts to constrain their detailed radial and vertical structure, and to characterise the gas content. We constrained the radial and vertical distribution of dust, as well as the presence of asymmetries. For a subset of six belts with CO gas, we constrained the gas distribution and kinematics. To interpret these observations, we used a wide range of dynamical models. The first ARKS results are presented as a series of ten papers. We discovered that up to 33% of our sample exhibits multiple dusty rings. For highly inclined belts, we found that non-Gaussian vertical distributions are common and are indicative of multiple dynamical populations. We also found that 10 of the 24 belts present asymmetries. We find that the CO gas is radially broader than the dust, but this could be an effect of optical depth. At least one system shows non-Keplerian kinematics due to strong pressure gradients, which may have triggered a vortex that trapped dust in an arc. Finally, we find evidence that the micron-sized grains may be affected by gas drag in gas rich systems. ARKS has revealed a great diversity of structures in exoKuiper belts that may arise when they are formed in protoplanetary discs or subsequently via interactions with planets and/or gas. We encourage the community to explore the reduced data and data products.

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arXiv2026

The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) VII: Optically thick gas with broad CO gaussian local line profiles in the HD 121617 disc

CO gas has been detected in $\sim$20 debris discs. We present ALMA observations of the CO-rich HD 121617 debris disc from the ARKS survey. Using high-resolution Band 7 observations of $^{12}CO \ J=3-2$, we analyse local CO line profiles to investigate optical depth, CO mass, and temperature. Spectra are aligned and stacked in concentric annuli to produce local line profiles. The resulting profiles are Gaussian-shaped and broadened by Keplerian shear. The line profiles are modelled using both a simplified toy model and a RADMC-3D model including projection effects and Keplerian shear. Fitting the RADMC-3D model to the $^{13}$CO data, we find that an optically thick model with a temperature of 38 K and a CO mass of $2 \times 10^{-3}$ M$_{\oplus}$ reproduces the observations. The model reproduces the enhanced emission at orbital azimuths of $\sim \pm45^{\circ}$ and $\pm135^{\circ}$, forming an X-shaped structure in the velocity-integrated intensity map, as well as the broader $^{12}$CO linewidth relative to $^{13}$CO. Scaling the model by the ISM abundance ratio ($\sim$77) also reproduces the $^{12}$CO data, though high optical depths and model assumptions limit mass constraints. We find that azimuthally averaged local line profiles appear Gaussian regardless of optical depth, cautioning against their use for distinguishing optically thin and thick emission. We constrain the mean molecular weight to $12.6_{-1.1}^{+1.3}$, dependent on model assumptions. Our $^{13}$CO results suggest that C$^{18}$O may also be optically thick in CO-rich debris discs and that the mean molecular weight is significantly higher than if H$_2$ were the dominant gas species, suggesting a non-primordial composition.

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arXiv2026

The ALMA survey to Resolve exoKuiper belt Substructures (ARKS): VI. Asymmetries and offsets

Asymmetries in debris discs provide unique clues to understand the evolution and architecture of planetary systems.** The aim of the ALMA survey to Resolve exoKuiper belt Substructures (ARKS) is to expand our understanding of radial and vertical dust structures, as well as gas distributions and kinematics, in debris discs.** Here, in ARKS~VI, we present a systematic analysis of the asymmetries and stellocentric offsets present in the ALMA continuum data for the ARKS survey. Our aims are to identify asymmetries in debris disc dust distributions, quantify debris disc asymmetry properties, and discuss the potential origins of debris disc asymmetries.** We utilised empirical methods to identify emission asymmetries** and the presence of offset emission between disc centres and the locations of the host stars, via an analysis of their calibration procedures and disc properties. We associated observational asymmetry types** and plausible physical classes** associated with each source. We show that there are ten systems, almost half of the ARKS sample, that host either a continuum emission asymmetry or offset emission. Three systems host offsets (HD15115, HD32297, and HD109573 (HR4796)), four host azimuthal asymmetries (HD9672 (49Ceti), HD92945, HD107146, and HD121617), two host an asymmetry in their major axis (HD10647 (q$^1$ Eri), and HD39060 ($β$ Pic)), and one hosts an asymmetry in their minor axis (HD61005). We attribute the offset asymmetries to non-zero eccentricities, and three of the azimuthal asymmetries to arcs. The presence of an asymmetry or offset in the ARKS sample appears to be correlated with the fractional luminosity of cold dust.** Conclusions: This study demonstrates that debris disc asymmetries in the ARKS sample are common, and plausibly so in the wider population of debris discs at (sub)-millimetre wavelengths.** ** = ABRIDGED FOR ARXIV: FULL ABSTRACT IN PAPER

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arXiv2026

The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) IV: CO gas imaging and overview

CO gas is detected in a significant number of debris discs, but its origin and evolution remains unclear. Key constraints are its mass and spectro-spatial distribution, which are coupled through optical depth and have only been analysed at low to moderate resolution so far. The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) is the first ALMA large program to target debris discs at high spectro-spatial resolution. We used $^{12}$CO and $^{13}$CO J=3-2 line data of 18 ARKS debris belts, 5 of which were already known to host gas, to analyse the spectro-spatial distribution of CO, constrain the gas masses, and to search for gas in the remaining systems. We developed a line-imaging pipeline and produced line cubes for each disc, with a spatial resolution down to $\sim$70 mas and spectral resolution of 26 m s$^{-1}$. Using spectro-spatial shifting and stacking, we produced high signal-to-noise maps, and radial and spectral profiles that reveal the distribution and kinematics of gas in 5 gas-bearing discs. For these discs, we constrained the inner radius of the $^{12}$CO, and found the radial brightness profile of CO peaked interior to the dust ring, but that CO was more radially extended than the dust. We present the first radially resolved $^{12}$CO/$^{13}$CO isotopologue flux ratios in gas-bearing debris discs, which are constant with radius for the majority of systems, indicating $^{12}$CO and $^{13}$CO are both optically thick or thin throughout the discs. We report CO line fluxes/upper limits for all systems and optical depth dependant masses for the 5 gas-bearing systems. Finally, we analysed the $^{12}$CO J=3-2 line luminosities for the ARKS debris discs and discs from the literature. We confirm that gas is mostly detected in young systems. However, the high scatter seen in young/high fractional luminosity systems indicates no trend within the systems with detected gas.

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arXiv2025

Systematic determination of dust properties for a sample of 133 spatially resolved debris discs

Determination of the composition and size distribution of dust grains in debris discs is strongly dependent on constraining the underlying spatial distribution of that dust through multi-wavelength, spatially resolved imaging spanning near-infrared to millimetre wavelengths. To date, spatially resolved imaging exists for well over a hundred debris disc systems. Simple analytical radiative transfer models of debris dust emission can reveal trends in disc properties as a function of their host stars' luminosities. Here we present such an analysis for 133 debris discs, calculating the dust grain minimum sizes ($s_{\rm min}$), dust masses ($M_{\rm dust}$), and exponents of the size distribution ($q$) in conjunction with their architectures determined at far-infrared or millimetre wavelengths. The distribution of $q$ at far-infrared to millimetre wavelengths is characterised for the first time, finding a value of $3.49^{+0.38}_{-0.33}$. We further newly identify a trend between $q$ and $R_{\rm disc}$, which may be indicative of velocity dependent fragmentation, or grain growth at large radii. We find the disc masses inferred from this analysis are consistent with those of protoplanetary discs. Finally, we identify samples of debris discs suitable for further characterisation at millimetre and centimetre wavelengths, expanding the number of spatially resolved systems upon which future studies of these statistics can be based.

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arXiv2025

{\sc ampere}: A tool to fit heterogeneous observations consistently

As astronomy advances and data becomes more complex, models and inference also become more expensive and complex. In this paper we present {\sc ampere}, which aims to solve this problem using modern inference techniques such as flexible likelihood functions and likelihood-free inference. {\sc ampere}\ can be used to do Bayesian inference even with very expensive models (hours of CPU time per model) that do not include all the features of the observations (e.g. missing lines, incomplete descriptions of PSFs, etc). We demonstrate the power of \ampere\ using a number of simple models, including inferring the posterior mineralogy of circumstellar dust using a Monte Carlo Radiative Transfer model. {\sc ampere}\ reproduces the input parameters well in all cases, and shows that some past studies have tended to underestimate the uncertainties that should be attached to the parameters. {\sc ampere}\ can be applied to a wide range of problems, and is particularly well-suited to using expensive models to interpret data.

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arXiv2025

The Nearby Evolved Stars Survey III: First data release of JCMT CO-line observations

Low- to intermediate-mass ($\sim$0.8$-$8 M$_\odot$) evolved stars contribute significantly to the chemical enrichment of the interstellar medium in the local Universe, making accurate mass-return estimates in their final stages crucial. The Nearby Evolved Stars Survey (NESS) is a large multi-telescope project targeting a volume-limited sample of $\sim$850 stars within 3 kpc in order to derive the dust and gas return rates in the Solar Neighbourhood, and to constrain the physics underlying these processes. We present an initial analysis of the CO-line observations, including detection statistics, carbon isotopic ratios, initial mass-loss rates, and gas-to-dust ratios. We describe a new data reduction pipeline to analyse the available NESS CO data from the JCMT, measuring line parameters and calculating empirical gas mass-loss rates. We present the first release of the available data on 485 sources, one of the largest homogeneous samples of CO data to date. Comparison with a large literature sample finds that high mass-loss rate and especially carbon-rich sources are over-represented in literature, while NESS is probing significantly more sources at low mass-loss rates, detecting 59 sources in CO for the first time and providing useful upper limits. CO line detection rates are 81% for the CO (2--1) line and 75% for CO (3--2). The majority (82%) of detected lines conform to the expected soft parabola shape, while eleven sources show a double wind. Calculated mass-loss rates show power-law relations with both the dust-production rates and expansion velocities up to $\sim 5 \times 10^{-6}$~\msunyr. Median gas-to-dust ratios of 250 and 680 are found for oxygen-rich and carbon-rich sources, respectively. Our analysis of CO observations in this first data release highlights the importance of our volume-limited approach in characterizing the local AGB population as a whole.

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arXiv2025

ALMA millimetre-wavelength imaging of HD 138965: New constraints on the debris dust composition and presence of planetary companions

HD 138965 is a young A type star and member of the nearby young Argus association. This star is surrounded by a broad, bright debris disc with two temperature components that was spatially resolved at far-infrared wavelengths by Herschel. Here we present ALMA millimetre-wavelength imaging of the cool outer belt. These reveal its radial extent to be $150^{+10}_{-7}$ au with a width ($σ$) of 49$^{+7}_{-6}$ au ($ΔR/R$ = 0.77), at a moderate inclination of 49$\fdeg$9^{+3.3}_{-3.7}$. Due to the limited angular resolution, signal-to-noise, and inclination we have no constraint on the disc's vertical scale height. We modelled the disc emission with both gravitational and radiation forces acting on the dust grains. As the inner belt has not been spatially resolved, we fixed its radius and width prior to modelling the outer belt. We find astronomical silicate is the best fit for the dust composition. However, we could not reject possible scenarios where there are at least 10 \% water-ice inclusions. Combining the spatially resolved imaging by ALMA with non-detection at optical wavelengths by HST, we obtain a limit on the scattering albedo $ω\leq 0.09$ for the debris dust in the outer belt. Analysis of the outer belt's architecture in conjunction with simple stirring models places a mass limit of $2.3~\pm~0.4 M_{\rm Jup}$ on a companion interior to the belt ($a \leq 78$ au), a factor of two improvement over constraints from high contrast imaging.

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arXiv2025

The Nearby Evolved Stars Survey (NESS) V: properties of volume-limited samples of Galactic evolved stars

We provide a meta-study of the statistical and individual properties of two volume-complete sets of evolved stars in the Solar Neighbourhood: (1) 852 stars from the Nearby Evolved Stars Survey (NESS), and (2) a partially overlapping set of 507 evolved stars within 300 pc. We also investigate distance determinations to these stars, their luminosity functions and their spatial distribution. Gaia APSIS GSP-Phot AENEAS temperatures of bright giant stars often appear to be underestimated. Existing literature on AGB stars under-samples both the most and least extreme nearby dust-producing stars. We reproduce the literature star-formation history of the solar neighbourhood, though stellar-evolution models over-predict the number of AGB stars of ages around 500 Myr. The distribution of AGB stars broadly matches the known 300 pc scale height of the Galactic disc and shows concentration in the direction of the Galactic centre. Most dust-producing carbon stars belong to the Galactic thick-disc population.

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arXiv2025

Environmental effects on nearby debris discs

We probe the effect of the ISM on debris disc occurrence rates and on the morphologies of the discs. We used results from the Herschel Space Observatory DUNES and DEBRIS surveys of 295 nearby FGK dwarf stars imaged at 100 $μ$m and 160 $μ$m. Most of the 48 debris discs in this sample have small optical depths, making them more likely to be affected by the ISM compared to optically thick discs. Since the stars in our sample are located within the Local Interstellar Cloud, we can infer that their debris discs encounter similar conditions. This allows us to use the stellar space velocity as a single indicator of the forces that can act on the debris disc dust grains when they interact with the ISM. The observed debris disc occurrence rates seem to depend on the stellar space velocities, as expected under the hypothesis that stars with higher space velocities have a higher probability of losing their circumstellar dust. The percentage of sources with debris discs in our sample reaches a maximum of $\approx$25% for stars with low space velocity component values, $|U_{\mathrm{rel}}|$, relative to the local ISM, and decreases for larger $|U_{\mathrm{rel}}|$ values down to the 10% level. A decrease in the average disc fractional luminosity as a function of $|U_{\mathrm{rel}}|$ is also observed. These dependences do not disappear after accounting for the reported higher dispersion of $U$ values with age. In extended discs, the impact of the ISM could also explain the links observed between the stellar space velocities and the debris disc projected ellipticities, position angles, and radii. Although these indications may not be fully conclusive on their own, they collectively reinforce the hypothesis that the ISM influences the occurrence rates and morphologies of debris discs.

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arXiv2025

REsolved ALMA and SMA Observations of Nearby Stars (REASONS): A population of 74 resolved planetesimal belts at millimetre wavelengths

Planetesimal belts are ubiquitous around nearby stars, and their spatial properties hold crucial information for planetesimal and planet formation models. We present resolved dust observations of 74 planetary systems as part of the REsolved ALMA and SMA Observations of Nearby Stars (REASONS) survey and archival reanalysis. We uniformly modelled interferometric visibilities for the entire sample to obtain the basic spatial properties of each belt, and combined these with constraints from multi-wavelength photometry. We report key findings from a first exploration of this legacy dataset: (1) Belt dust masses are depleted over time in a radially dependent way, with dust being depleted faster in smaller belts, as predicted by collisional evolution. (2) Most belts are broad discs rather than narrow rings, with much broader fractional widths than rings in protoplanetary discs. We link broad belts to either unresolved substructure or broad planetesimal discs produced if protoplanetary rings migrate. (3) The vertical aspect ratios (h = H/R) of 24 belts indicate orbital inclinations of 1-20 degrees, implying relative particle velocities of 0.1-4 km/s, and no clear evolution of heights with system age. This could be explained by early stirring within the belt by large bodies (with sizes of at least 140 km to the size of the Moon), by inheritance of inclinations from the protoplanetary disc stage, or by a diversity in evolutionary pathways and gravitational stirring mechanisms. We release the REASONS legacy multidimensional sample of millimetre-resolved belts to the community as a valuable tool for follow-up multi-wavelength observations and population modelling studies.

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arXiv2023

The high-albedo, low polarization disk around HD 114082 harbouring a Jupiter-sized transiting planet

We present new optical and near-IR images of debris disk around the F-type star HD 114082. We obtained direct imaging observations and analysed the TESS photometric time series data of this target with a goal to search for planetary companions and to characterise the morphology of the debris disk and the scattering properties of dust particles. HD 114082 was observed with the VLT/SPHERE instrument: the IRDIS camera in the K band together with the IFS in the Y, J and H band using the ADI technique as well as IRDIS in the H band and ZIMPOL in the I_PRIME band using the PDI technique. The scattered light images were fitted with a 3D model for single scattering in an optically thin dust disk. We performed aperture photometry in order to derive the scattering and polarized phase functions, polarization fraction and spectral scattering albedo for the dust particles in the disk. This method was also used to obtain the reflectance spectrum of the disk to retrieve the disk color and study the dust reflectivity in comparison to the debris disk HD 117214. We also performed the modeling of the HD 114082 light curve measured by TESS using the models for planet transit and stellar activity to put constraints on radius of the detected planet and its orbit. The debris disk appears as an axisymmetric debris belt with a radius of ~0.37$"$ (35 au), inclination of ~83$^\circ$ and a wide inner cavity. Dust particles in HD 114082 have a maximum polarization fraction of ~17% and a high reflectivity which results in a spectral scattering albedo of 0.65. The analysis of TESS photometric data reveals a transiting planetary companion to HD 114082 with a radius of $\sim$1~$\rm R_{J}$ on an orbit with a semi-major axis of $0.7 \pm 0.4$ au. Combining different data, we reach deep sensitivity limits in terms of companion masses down to ~5$M_{\rm Jup}$ at 50 au, and ~10 $M_{\rm Jup}$ at 30 au from the central star.

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arXiv2022

The SHARDDS survey: limits on planet occurrence rates based on point sources analysis via the Auto-RSM framework

In the past decade, HCI surveys provided new insights about the frequency and properties of substellar companions at separation larger than 5 au. In this context, our study aims to detect and characterise potential exoplanets and brown dwarfs within debris disks, by considering the SHARDDS survey, which gathers 55 Main Sequence stars with known bright debris disk. We rely on the AutoRSM framework to perform an in-depth analysis of the targets, via the computation of detection maps and contrast curves. A clustering approach is used to divide the set of targets in multiple subsets, in order to reduce the computation time by estimating a single optimal parametrisation for each considered subset. The use of Auto-RSM allows to reach high contrast at short separations, with a median contrast of 10-5 at 300 mas, for a completeness level of 95%. Detection maps generated with different approaches are used along with contrast curves, to identify potential planetary companions. A new planetary characterisation algorithm, based on the RSM framework, is developed and tested successfully, showing a higher astrometric and photometric precision for faint sources compared to standard approaches. Apart from the already known companion of HD206893 and two point-like sources around HD114082 which are most likely background stars, we did not detect any new companion around other stars. A correlation study between achievable contrasts and parameters characterising HCI sequences highlights the importance of the strehl, wind speed and wind driven halo to define the quality of high contrast images. Finally, planet detection and occurrence frequency maps are generated and show, for the SHARDDS survey, a high detection rate between 10 and 100 au for substellar companions with mass >10MJ.

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arXiv2021

The Nearby Evolved Stars Survey II: Constructing a volume-limited sample and first results from the James Clerk Maxwell Telescope

The Nearby Evolved Stars Survey (NESS) is a volume-complete sample of $\sim$850 Galactic evolved stars within 3\,kpc at (sub-)mm wavelengths, observed in the CO $J = $ (2$-$1) and (3$-$2) rotational lines, and the sub-mm continuum, using the James Clark Maxwell Telescope and Atacama Pathfinder Experiment. NESS consists of five tiers, based on distances and dust-production rate (DPR). We define a new metric for estimating the distances to evolved stars and compare its results to \emph{Gaia} EDR3. Replicating other studies, the most-evolved, highly enshrouded objects in the Galactic Plane dominate the dust returned by our sources, and we initially estimate a total DPR of $4.7\times 10^{-5}$ M$_\odot$ yr$^{-1}$ from our sample. Our sub-mm fluxes are systematically higher and spectral indices are typically shallower than dust models typically predict. The 450/850 $μ$m spectral indices are consistent with the blackbody Rayleigh--Jeans regime, suggesting a large fraction of evolved stars have unexpectedly large envelopes of cold dust.

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arXiv2021

A thermophysical and dynamical study of the Hildas (1162) Larissa and (1911) Schubart

The Hilda asteroids are among the least studied populations in the asteroid belt, despite their potential importance as markers of Jupiter's migration in the early Solar system. We present new mid-infrared observations of two notable Hildas, (1162) Larissa and (1911) Schubart, obtained using the Faint Object infraRed CAmera for the SOFIA Telescope (FORCAST), and use these to characterise their thermal inertia and physical properties. For (1162) Larissa, we obtain an effective diameter of \textcolor{black}{46.5$^{+2.3}_{-1.7}$~km, an albedo of 0.12~$\pm$~0.02, and a thermal inertia of 15$^{+10}_{-8}$ Jm$^{-2}$s$^{1/2}$K$^{-1}$. In addition, our Larissa thermal measurements are well matched with an ellipsoidal shape with an axis ratio a/b=1.2 for the most-likely spin properties. Our modelling of (1911) Schubart is not as refined, but the thermal data point towards a high-obliquity spin-pole, with a best-fit a/b=1.3 ellipsoidal shape. This spin-shape solution is yielding a diameter of 72$^{+3}_{-4}$ km, an albedo of 0.039$\pm$~0.02, and a thermal inertia below 30 Jm$^{-2}$s$^{1/2}$K$^{-1}$ (or 10$^{+20}_{-5}$Jm$^{-2}$s$^{1/2}$K$^{-1}$).} As with (1162) Larissa, our results suggest that (1911) Schubart is aspherical, and likely elongated in shape. Detailed dynamical simulations of the two Hildas reveal that both exhibit strong dynamical stability, behaviour that suggests that they are primordial, rather than captured objects. The differences in their albedos, along with their divergent taxonomical classification, suggests that despite their common origin, the two have experienced markedly different histories.

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arXiv2020

Stability analysis of three exoplanet systems

The orbital solutions of published multi-planet systems are not necessarily dynamically stable on timescales comparable to the lifetime of the system as a whole. For this reason, dynamical tests of the architectures of proposed exoplanetary systems are a critical tool to probe the stability and feasibility of the candidate planetary systems, with the potential to point the way towards refined orbital parameters of those planets. Such studies can even help in the identification of additional companions in such systems. Here we examine the dynamical stability of three planetary systems, orbiting HD 67087, HD 110014, and HD 133131A. We use the published radial velocity measurements of the target stars to determine the best-fit orbital solutions for these planetary systems using the Systemic console. We then employ the n-body integrator Mercury to test the stability of a range of orbital solutions lying within 3-$σ$ of the nominal best-fit for a duration of 100 Myr. From the results of the n-body integrations, we infer the best-fit orbital parameters using the Bayesian package Astroemperor. We find that both HD 110014 and HD 133131A have long-term stable architectures that lie within the 1-$σ$ uncertainties of the nominal best-fit to their previously determined orbital solutions. However, the HD 67087 system exhibits a strong tendency toward instability on short timescales. We compare these results to the predictions made from consideration of the angular momentum deficit criterion, and find that its predictions are consistent with our findings.

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arXiv2020

Multi-wavelength, spatially resolved modelling of HD 48682's debris disc

Asteroids and comets (planetesimals) are created in gas- and dust-rich protoplanetary discs. The presence of these planetesimals around main-sequence stars is usually inferred from the detection of excess continuum emission at infrared wavelengths from dust grains produced by destructive processes within these discs. Modelling of the disc structure and dust grain properties for those discs is often hindered by the absence of any meaningful constraint on the location and spatial extent of the disc. Multi-wavelength, spatially resolved imaging is thus invaluable in refining the interpretation of these systems. Observations of HD 48682 at far-infrared (Spitzer,Herschel) and sub-millimetre (JCMT, SMA) wavelengths indicated the presence of an extended, cold debris disc with a blackbody temperature of 57.9 +\- 0.7 K. Here, we combined these data to perform a comprehensive study of the disc architecture and its implications for the dust grain properties. The deconvolved images revealed a cold debris belt, verified by combining a 3D radiative transfer dust continuum model with image analysis to replicate thestructure using a single, axisymmetric annulus. A Markov chain Monte Carlo analysis calculated the maximum likelihood of HD 48682's disc radius (Rdisc = 89 +17 -20 au), fractional width(DeltaRdisc = 0.41 +0.27 -0.20), position angle (theta = 66.3 +4.5 -4.9 degrees), and inclination (phi = 112.5 +4.2 -4.2 degrees). HD 48682 has been revealed to host a collisionally active, broad disc whose emission is dominated by small dust grains, smin approx. 0.6 microns, and a size distribution exponent of 3.60 +\- 0.02.

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