ORCID Profile
0000-0002-2357-7692
Current Organisation
Università degli Studi di Milano
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Oxford University Press (OUP)
Date: 27-01-2016
DOI: 10.1093/MNRAS/STW034
Publisher: American Astronomical Society
Date: 04-2022
Abstract: We map the planetary wake associated with the embedded protoplanet creating the CO kink in the disk of HD 163296. We show that the wake can be traced by a series of correlated perturbations in the peak velocity map. The sign change of the perturbations across the disk’s major axis confirms that the wake induces predominantly radial motion, as predicted by models of planet–disk interaction. These results provide the first direct confirmation of planet wakes generated by Lindblad resonances. Mapping the wake provides a constraint on the disk aspect ratio, which is required to measure the mass of the planet.
Publisher: American Astronomical Society
Date: 06-08-2013
Publisher: Oxford University Press (OUP)
Date: 27-09-2016
Publisher: Oxford University Press (OUP)
Date: 05-09-2019
Abstract: Recent observations of protoplanetary discs reveal disc substructures potentially caused by embedded planets. We investigate how the gas surface density in discs changes the observed morphology in scattered light and dust continuum emission. Assuming that disc substructures are due to embedded protoplanets, we combine hydrodynamical modelling with radiative transfer simulations of dusty protoplanetary discs hosting planets. The response of different dust species to the gravitational perturbation induced by a planet depends on the drag stopping time — a function of the generally unknown local gas density. Small dust grains, being stuck to the gas, show spirals. Larger grains decouple, showing progressively more axisymmetric (ring-like) substructure as decoupling increases with grain size or with the inverse of the gas disc mass. We show that simultaneous modelling of scattered light and dust continuum emission is able to constrain the Stokes number, St. Hence, if the dust properties are known, this constrains the local gas surface density, Σgas, at the location of the structure, and hence the total gas mass. In particular, we found that observing ring-like structures in mm-emitting grains requires St ≳ 0.4 and therefore Σgas ≲ 0.4 g/cm2. We apply this idea to observed protoplanetary discs showing substructures both in scattered light and in the dust continuum.
Publisher: Oxford University Press (OUP)
Date: 07-11-2017
Publisher: Springer International Publishing
Date: 2018
Publisher: Oxford University Press (OUP)
Date: 08-2022
Abstract: We present new high-contrast images in near-infrared wavelengths (λc = 1.04, 1.24, 1.62, 2.18, and 3.78 μm) of the young variable star CQ Tau, aiming to constrain the presence of companions in the protoplanetary disc. We reached a Ks-band contrast of 14 mag with SPHERE/IRDIS at separations greater than 0${_{.}^{\\prime\\prime}}$4 from the star. Our mass sensitivity curve rules out giant planets above 4 MJup immediately outside the spiral arms at ∼60 au and above 2–3 MJup beyond 100 au to 5σ confidence assuming hot-start models. We do, however, detect four spiral arms, a double-arc and evidence for shadows in scattered light cast by a misaligned inner disc. Our observations may be explained by an unseen close-in companion on an inclined and eccentric orbit. Such a hypothesis would also account for the disc CO cavity and disturbed kinematics.
Publisher: Oxford University Press (OUP)
Date: 09-05-2020
Abstract: Recent millimetre-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 $M_{\\rm p}=3.5\\, \\mathrm{ M}_{\\rm Jup}$ and a disc with $M_{\\rm dust}= 9.6\\,\\times \\,10^{-5}\\, \\mathrm{ M}_{\\odot }$. 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.
Publisher: Oxford University Press (OUP)
Date: 27-04-2021
Abstract: A new technique to detect protoplanets is by observing the kinematics of the surrounding gas. Gravitational perturbations from a planet produce peculiar ‘kinks’ in channel maps of different gas species. In this paper, we show that such kinks can be reproduced using semi-analytic models for the velocity perturbation induced by a planet. In doing so we (i) confirm that the observed kinks are consistent with the planet-induced wake (ii) show how to quantify the planet mass from the kink litude in particular, we show that the kink litude scales with the square root of the planet mass for channels far from the planet velocity, steepening to linear as the channels approach the planet and (iii) show how to extend the theory to include the effect of d ing, which may be needed in order to have localized kinks.
Publisher: Oxford University Press (OUP)
Date: 03-2016
Publisher: Oxford University Press (OUP)
Date: 03-12-2021
Abstract: We present an online, open, and comprehensive template library of gravitational waveforms produced during the tidal disruptions of stars by massive black holes, spanning a broad space of parameters. We build this library thanks to a new feature that we implement in the general relativistic version of phantom, a smoothed particle hydrodynamics code for three dimensional simulations in general relativity. We first perform a series of numerical tests to show that the gravitational wave (GW) signal obtained is in excellent agreement with the one expected from theory. This benchmark is done for well studied scenarios (such as binary stellar systems). We then apply our code to calculate the GW signals from tidal disruption events, finding that our results are consistent with the theoretical estimates obtained in previous studies for selected parameters. We illustrate interesting results from the catalog, where we stress how the gravitational signal is affected by variations of some parameters (like black hole spin, stellar orbital eccentricity, and inclination). The full catalog is available online. It is intended to be a living catalog.
Publisher: Oxford University Press (OUP)
Date: 25-08-2015
Publisher: Oxford University Press (OUP)
Date: 02-10-2021
Abstract: Gas and dust in inclined orbits around binaries experience precession induced by the binary gravitational torque. The difference in precession between gas and dust alters the radial drift of weakly coupled dust and leads to density enhancements where the radial drift is minimized. We explore this phenomenon using 3D hydrodynamical simulations to investigate the prominence of these ‘dust traffic jams’ and the evolution of the resulting dust sub-structures at different disc inclinations and binary eccentricities. We then derive evolution equations for the angular momentum of warped dust discs and implement them in a 1D code and present calculations to further explain these traffic jams. We find that dust traffic jams in inclined circumbinary discs provide significant dust density enhancements that are long lived and can have important consequences for planetesimal formation.
Publisher: Oxford University Press (OUP)
Date: 30-07-2021
Abstract: IRAS 04158+2805 has long been thought to be a very low mass T-Tauri star (VLMS) surrounded by a nearly edge-on, extremely large disc. Recent observations revealed that this source hosts a binary surrounded by an extended circumbinary disc with a central dust cavity. In this paper, we combine ALMA multiwavelength observations of continuum and 12CO line emission, with H α imaging and Keck astrometric measures of the binary to develop a coherent dynamical model of this system. The system features an azimuthal asymmetry detected at the western edge of the cavity in Band 7 observations and a wiggling outflow. Dust emission in ALMA Band 4 from the proximity of the in idual stars suggests the presence of marginally resolved circumstellar discs. We estimate the binary orbital parameters from the measured arc of the orbit from Keck and ALMA astrometry. We further constrain these estimates using considerations from binary–disc interaction theory. We finally perform three SPH gas+dust simulations based on the theoretical constraints we post-process the hydrodynamic output using radiative transfer Monte Carlo methods and directly compare the models with observations. Our results suggest that a highly eccentric e ∼ 0.5–0.7 equal mass binary, with a semimajor axis of ∼55 au, and small/moderate orbital plane versus circumbinary disc inclination θ ≲ 30° provides a good match with observations. A dust mass of ${\\sim}1.5\\times 10^{-4} \\, {\\rm M_\\odot }$ best reproduces the flux in Band 7 continuum observations. Synthetic CO line emission maps qualitatively capture both the emission from the central region and the non-Keplerian nature of the gas motion in the binary proximity.
Publisher: Oxford University Press (OUP)
Date: 25-09-2020
Abstract: The disc surrounding PDS 70, with two directly imaged embedded giant planets, is an ideal laboratory to study planet–disc interaction. We present 3D 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 on to 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.
Publisher: Oxford University Press (OUP)
Date: 16-03-2018
DOI: 10.1093/MNRAS/STY642
Publisher: Cambridge University Press (CUP)
Date: 2018
DOI: 10.1017/PASA.2018.25
Abstract: We present Phantom , a fast, parallel, modular, and low-memory smoothed particle hydrodynamics and magnetohydrodynamics code developed over the last decade for astrophysical applications in three dimensions. The code has been developed with a focus on stellar, galactic, planetary, and high energy astrophysics, and has already been used widely for studies of accretion discs and turbulence, from the birth of planets to how black holes accrete. Here we describe and test the core algorithms as well as modules for magnetohydrodynamics, self-gravity, sink particles, dust–gas mixtures, H 2 chemistry, physical viscosity, external forces including numerous galactic potentials, Lense–Thirring precession, Poynting–Robertson drag, and stochastic turbulent driving. Phantom is hereby made publicly available.
Publisher: Oxford University Press (OUP)
Date: 22-02-2021
Abstract: 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 ∼0.7-arcsec separation from CrA-9 (∼108 au projected separation). Our 3-epoch astrometry rejects a fixed background star with a 5σ 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-μm 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.
Publisher: Oxford University Press (OUP)
Date: 17-05-2017
Publisher: Oxford University Press (OUP)
Date: 17-06-2013
DOI: 10.1093/MNRAS/STT877
Publisher: Oxford University Press (OUP)
Date: 03-2010
Publisher: Oxford University Press (OUP)
Date: 20-11-2015
Publisher: Oxford University Press (OUP)
Date: 21-10-2019
Abstract: Tidal encounters in star clusters perturb discs around young protostars. In Cuello et al., 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) millimetre 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 multiwavelength observations. This provides a reference to identify flybys in recent near-infrared and submillimetre observations (e.g. RW Aur, AS 205, HV Tau and DO Tau, FU Ori, V2775 Ori, and Z CMa).
Publisher: Oxford University Press (OUP)
Date: 11-05-2023
Abstract: Young protostellar discs are likely to be both self-gravitating, and to support grain growth to sizes where the particles decoupled from the gas. This combination could lead to short-wavelength fragmentation of the solid component in otherwise non-fragmenting gas discs, forming Earth-mass solid cores during the Class 0/I stages of young stellar object evolution. We use three-dimensional smoothed particle hydrodynamics simulations of two-fluid discs, in the regime where the Stokes number of the particles St & 1, to study how the formation of solid clumps depends on the disc-to-star mass ratio, the strength of gravitational instability, and the Stokes number. Gravitational instability of the simulated discs is sustained by local cooling. We find that the ability of the spiral structures to concentrate solids increases with the cooling time and decreases with the Stokes number, while the relative dynamical temperature between gas and dust of the particles decreases with the cooling time and the disc-to-star mass ratio and increases with the Stokes number. Dust collapse occurs in a subset of high disc mass simulations, yielding clumps whose mass is close to linear theory estimates, namely 1–10 M⊕. Our results suggest that if planet formation occurs via this mechanism, the best conditions correspond to near the end of the self-gravitating phase, when the cooling time is long and the Stokes number close to unity.
Publisher: Oxford University Press (OUP)
Date: 15-03-2018
DOI: 10.1093/MNRAS/STY647
Publisher: Oxford University Press (OUP)
Date: 25-05-2022
Abstract: Young multiple systems accrete most of their final mass in the first few Myr of their lifetime, during the protostellar and protoplanetary phases. Previous studies showed that in binary systems the majority of the accreted mass falls on to the lighter star, thus evolving to mass equalization. However, young stellar systems often comprise more than two stars, which are expected to be in hierarchical configurations. Despite its astrophysical relevance, differential accretion in hierarchical systems remains to be understood. In this work, we investigate whether the accretion trends expected in binaries are valid for higher order multiples. We performed a set of three-dimensional smoothed particle hydrodynamics simulations of binaries and of hierarchical triples (HTs) embedded in an accretion disc, with the code phantom. We identify for the first time accretion trends in HTs and their deviations compared to binaries. These deviations, due to the interaction of the small binary with the infalling material from the circumtriple disc, can be described with a semi-analytical prescription. Generally, the smaller binary of an HT accretes more mass than a single star of the same mass as the smaller binary. We found that in an HT, if the small binary is heavier than the third body, the standard differential accretion scenario (whereby the secondary accretes more of the mass) is h ered. Reciprocally, if the small binary is lighter than the third body, the standard differential accretion scenario is enhanced. The peculiar differential accretion mechanism we find in HTs is expected to affect their mass ratio distribution.
Publisher: American Astronomical Society
Date: 10-02-2020
Publisher: Oxford University Press (OUP)
Date: 06-05-2016
Publisher: Oxford University Press (OUP)
Date: 27-08-2012
Publisher: Oxford University Press (OUP)
Date: 20-12-2018
Publisher: Oxford University Press (OUP)
Date: 04-09-2018
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for GIUSEPPE LODATO.