The role of the energy equation in the fragmentation of protostellar discs during stellar encounters

In this paper, we use high-resolution smoothed particle hydrodynamics (SPH) simulations to investigate the response of a marginally stable self-gravitating protostellar disc to a close parabolic encounter with a companion discless star. Our main aim is to test whether close brown dwarfs or massive planets can form out of the fragmentation of such discs. We follow the thermal evolution of the disc by including the effects of heating due to compression and shocks and a simple prescription for cooling and find results that contrast with previous isothermal simulations. In the present case we find that fragmentation is inhibited by the interaction, due to the strong effect of tidal heating, which results in a strong stabilization of the disc. A similar behaviour was also previously observed in other simulations involving discs in binary systems. As in the case of isolated discs, it appears that the condition for fragmentation ultimately depends on the cooling rate.Comment: 9 pages, 10 figures, accepted in MNRA

Kinematics signature of a giant planet in the disk of AS 209

[abridged] ALMA observations of dust in protoplanetary disks are revealing the existence of sub-structures such as rings, gaps and cavities. Such morphology are expected to be the outcome of dynamical interaction between the disk and planets. However, other mechanisms are able to produce similar dust sub-structures. A solution is to look at the perturbation induced by the planet to the gas surface density and/or to the kinematics. In the case of the disk around AS 209, a prominent gap has been reported in the surface density of CO at $r \sim 100\,$au. Recently, Bae et al. (2022) detected a localized velocity perturbation in the $^{12}$CO $J=2-1$ emission along with a clump in $^{13}$CO $J=2-1$ at nearly 200 au, interpreted as a gaseous circumplanetary disk. We report a new analysis of ALMA archival observations of $^{12}$CO and $^{13}$CO J=2-1. A clear kinematics perturbation (kink) is detected in multiple channels and over a wide azimuth range in both dataset. We compared the observed perturbation with a semi-analytic model of velocity perturbations due to planet-disk interaction. The observed kink is not consistent with a planet at 200\,au as this would require a low gas disk scale height ($< 0.05$) in contradiction with previous estimate ($h/r \sim 0.118$ at $r = 100$ au). When we fix the disk scale height to 0.118 (at $r = 100$ au) we find instead that a planet of 3-5 M$_{\rm Jup}$ at 100 au induces a kinematics perturbation similar to the observed one. Thus, we conclude that a giant protoplanet orbiting at $r \sim 100\,$au is responsible of the large scale kink as well as of the perturbed dust and gas surface density previously detected. The position angle of the planet is constrained to be between 60$^{\circ}$-100$^{\circ}$. Future observations with high contrast imaging technique in the near- and mid- infrared are needed to confirm the presence and position of such a planet.Comment: Accepted by A&

Signatures of broken protoplanetary discs in scattered light and in sub-millimetre observations

Spatially resolved observations of protoplanetary discs are revealing that their inner regions can be warped or broken from the outer disc. A few mechanisms are known to lead to such 3D structures; among them, the interaction with a stellar companion. We perform a 3D SPH simulation of a circumbinary disc misaligned by 60\ub0 with respect to the binary orbital plane. The inner disc breaks from the outer regions, precessing as a rigid body and leading to a complex evolution. As the inner disc precesses, the misalignment angle between the inner and outer discs varies by more than 100\ub0. Different snapshots of the evolution are post-processed with a radiative transfer code, in order to produce observational diagnostics of the process. Even though the simulation was produced for the specific case of a circumbinary disc, most of the observational predictions hold for any disc hosting a precessing inner rim. Synthetic scattered light observations show strong azimuthal asymmetries, where the pattern depends strongly on the misalignment angle between the inner and outer discs. The asymmetric illumination of the outer disc leads to azimuthal variations of the temperature structure, in particular in the upper layers, where the cooling time is short. These variations are reflected in asymmetric surface brightness maps of optically thick lines, as CO J = 3 122. The kinematical information obtained from the gas lines is unique in determining the disc structure. The combination of scattered light images and (sub-)mm lines can distinguish between radial inflow and misaligned inner disc scenarios

Constraints from Dust Mass and Mass Accretion Rate Measurements on Angular Momentum Transport in Protoplanetary Disks

We investigate the relation between disk mass and mass accretion rate to constrain the mechanism of angular momentum transport in protoplanetary disks. Dust mass and mass accretion rate in Chamaeleon I are correlated with a slope close to linear, similar to the one recently identified in Lupus. We investigate the effect of stellar mass and find that the intrinsic scatter around the best-fit Mdust-Mstar and Macc-Mstar relations is uncorrelated. Disks with a constant alpha viscosity can fit the observed relations between dust mass, mass accretion rate, and stellar mass, but over-predict the strength of the correlation between disk mass and mass accretion rate when using standard initial conditions. We find two possible solutions. 1) The observed scatter in Mdust and Macc is not primoridal, but arises from additional physical processes or uncertainties in estimating the disk gas mass. Most likely grain growth and radial drift affect the observable dust mass, while variability on large time scales affects the mass accretion rates. 2) The observed scatter is primordial, but disks have not evolved substantially at the age of Lupus and Chamaeleon I due to a low viscosity or a large initial disk radius. More accurate estimates of the disk mass and gas disk sizes in a large sample of protoplanetary disks, either through direct observations of the gas or spatially resolved multi-wavelength observations of the dust with ALMA, are needed to discriminate between both scenarios or to constrain alternative angular momentum transport mechanisms such as MHD disk winds.Comment: See also the paper by Lodato et a

On dust evolution in planet-forming discs in binary systems: II. Comparison with Taurus and ρ Ophiuchus (sub-)millimetre observations: discs in binaries have small dust sizes

Interstellar matter and star formatio

On dust evolution in planet-forming discs in binary systems: I. Theoretical and numerical modelling: radial drift is faster in binary discs

Interstellar matter and star formatio

E-PTFE (Gore-Tex) implant with or without low-dosage mitomycin-C as an adjuvant in penetrating glaucoma surgery: 2 year randomized clinical trial.

Purpose: To test the expanded polytetrafluoroethylene (ePTFE) as a new adjuvant in trabeculectomy. Methods: Consecutive glaucoma surgical inpatients were observed at the Department of Ophthalmology of Palermo University. Sixty patients (60 eyes)were randomly assigned to undergo trabeculectomy (T), trabeculectomy with mitomycin-C (TMMC), with ePTFE (TG) or with mitomycin-C and ePTFE (TGMMC). Postoperative visits were scheduled at 24 hr, 7 days, 1, 3, 6, 12, 18 and 24 months. Complete success and qualified success were assessed at two target intraocular pressure (IOP) levels – £21 and £17 mmHg – by Kaplan–Meier curves. Results: The postoperative IOP reduction was significant (P < 0.01) at the endpoint in all groups, with a mean IOP of 16.9 (±2.9), 16.2 (±2.7), 15.3 (±3.4) and 15.2 (±4.3) mmHg in T, TMMC, TG and TGMMC eyes, respectively. No intergroup difference was found at either IOP targets. The Kaplan–Meier curves relating to either the £21 mmHg or the £17 mmHg target IOP did not show significant intergroup differences for complete and qualified success rate. When ePTFE was used, a trend favouring the medium-term survival rate was noted. No adverse reaction to the ePTFE was present, and no membrane extrusion or conjuctival erosion were noted in any cases. Hypotony was significantly more frequent (P = 0.035) in groups without ePTFE. Moreover, the late MMC-related complications were more frequent when MMC was applied. Conclusion: Expanded polytetrafluoroethylene implant in trabeculectomy is well tolerated and could act as a filtration modulating device. Therefore, it is useful in reducing early hypotony-related complications and contributes to attaining medium-term IOP control that is comparable to the low-dosage MMC

Adénocarcinome de la glande lacrymale dans un rétinoblastome bilatéral traité avec radiothérapie externe : à propos d’un cas

This clinical case report describes the clinical findings and diagnosis of lacrimal gland adenocarcinoma that developed 20 years after external beam radiotherapy in the treatment of bilateral retinoblastoma. Visual acuity, slit lamp biomicroscopy, fundus color photography, nuclear magnetic resonance, lateral orbitotomy and histological analysis are described

H2_2O distribution in the disc of HD 100546 and HD 163296: the role of dust dynamics and planet--disc interaction

[Abridged] Far-infrared observations with Herschel revealed a surprisingly low abundance of cold-water reservoirs in protoplanetary discs. On the other hand, a handful of discs show emission of hot water transitions excited at temperatures above a few hundred Kelvin. In particular, the protoplanetary discs around the Herbig Ae stars HD 100546 and HD 163296 show opposite trends in terms of cold versus hot water emission: in the first case, the ground-state transitions are detected and the high-J lines are undetected, while the trend is opposite in HD 163296. We performed a spectral analysis using the thermo-chemical model DALI. We find that HD 163296 is characterised by a water-rich (abundance $\gtrsim 10^{-5}$) hot inner disc (within the snowline) and a water-poor ($< 10^{-10}$) outer disc: the relative abundance may be due to the thermal desorption of icy grains that have migrated inward. Remarkably, the size of the H$_2$O emitting region corresponds to a narrow dust gap visible in the millimeter continuum at $r=10\,$au with ALMA. The low-J lines detected in HD 100546 instead imply an abundance of a few $10^{-9}$ in the cold outer disc ($> 40$ au). The emitting region of the cold H$_2$O transitions is spatially coincident with that of the H$_2$O ice previously seen in the near-infrared. Notably, millimetre observations with ALMA reveal the presence of a large dust gap between nearly 40 and 150 au, likely opened by a massive embedded protoplanet. In both discs, we find that the warm molecular layer in the outer region (beyond the snow line) is highly depleted of water molecules, implying an oxygen-poor chemical composition of the gas. We speculate that gas-phase oxygen in the outer disc is readily depleted and its distribution in the disc is tightly coupled to the dynamics of the dust grains.Comment: Accepted for publication on A&