Suchergebnisse

High dust density in the midplane of protoplanetary disks is favorable for efficient grain growth and can allow fast formation of planetesimals and planets, before disks dissipate. Vertical settling and dust trapping in pressure maxima are two mechanisms allowing dust to concentrate in geometrically thin and high-density regions. In this work, we aim to study these mechanisms in the highly inclined protoplanetary disk SSTC2D J163131.2-242627 (Oph 163131, i similar to 84 degrees). We present new high-angular-resolution continuum and (CO)-C-12 ALMA observations of Oph 163131. The gas emission appears significantly more extended in the vertical and radial direction compared to the dust emission, consistent with vertical settling and possibly radial drift. In addition, the new continuum observations reveal two clear rings. The outer ring, located at similar to 100 au, is well-resolved in the observations, allowing us to put stringent constraints on the vertical extent of millimeter dust particles. We model the disk using radiative transfer and find that the scale height of millimeter-sized grains is 0.5 au or less at 100 au from the central star. This value is about one order of magnitude smaller than the scale height of smaller micron-sized dust grains constrained by previous modeling, which implies that efficient settling of the large grains is occurring in the disk. When adopting a parametric dust settling prescription, we find that the observations are consistent with a turbulent viscosity coefficient of about alpha less than or similar to 10(-5) at 100 au. Finally, we find that the thin dust scale height measured in Oph 163131 is favorable for planetary growth by pebble accretion: a 10 M (E) planet may grow within less than 10 Myr, even in orbits exceeding 50 au. ; National Aeronautics & Space Administration (NASA) European Union's Horizon 2020 research and innovation program under the Marie Skodowska-Curie grant 210021 National Aeronautics & Space Administration (NASA) NNX15AC89G NNX15AD95G/NExSS ...

Context. We initiated a deep-imaging survey of Scorpius-Centaurus A-F stars in 2015. These stars are predicted to host warm inner and cold outer belts of debris reminiscent of the architecture of emblematic systems such as HR 8799. Aims. We present resolved images of a ring of debris around the F5-type star HD 141011 that was observed as part of our survey. We aim to set constraints on the properties of the disk, compare them to those of other resolved debris disks in Sco-Cen, and detect companions. Methods. We obtained high-contrast coronagraphic observations of HD 141011 in 2015, 2016, and 2019 with VLT/SPHERE. We removed the stellar halo using angular differential imaging. We searched for scattered light emission from a disk in the residuals and applied a forward-modeling approach to retrieve its morphological and photometric properties. We combined our radial velocity and imaging data to derive detection probabilities for companions co-planar with the disk orientation. Results. We resolve a narrow ring of debris that extends up to ∼1.100 (∼141 au) from the star in the IRDIS and IFS data obtained in 2016 and 2019. The disk is not detected in the 2015 data which are of poorer quality. The disks is best reproduced by models of a noneccentric ring centered on the star with an inclination of 69.1 ± 0.9 ◦ , a position angle of −24.6 ± 1.7 ◦ , and a semimajor axis of 127.5 ± 3.8 au. The combination of radial velocity and imaging data excludes brown-dwarf (M > 13.6 MJup) companions coplanar with the disk from 0.1 to 0.9 au and from 20 au up to 500 au (90% probability). Conclusions. HD 141011 adds to the growing list of debris disks that are resolved in Sco-Cen. It is one of the faintest disks that are resolved from the ground and has a radial extent and fractional width (∼12.5%) reminiscent of Fomalhaut. Its moderate inclination and large semimajor axis make it a good target for the James Webb Space Telescope and should allow a deeper search for putative companions shaping the dust distribution. ; French National Research Agency (ANR) ANR-14-CE33-0018 ANR-20-CE31-0012 France from the CNRS-D2P PICS grant France from the Programmes Nationaux de Planetologie et de Physique Stellaire (PNP) France from the Programmes Nationaux de Planetologie et de Physique Stellaire (PNPS) European Research Council (ERC) 885 593 Istituto Nazionale Astrofisica (INAF) Agenzia Spaziale Italiana (ASI) 2018-16-HH.0 PRIN-INAF 2019 "Planetary systems at young ages (PLATEA)" Australian Research Council FT170100040 DP180104235 ANID, -Millennium Science Initiative Program NCN19_171 Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) CONICYT FONDECYT 1180395 French National Research Agency (ANR) ANR10 LABX56 Spanish Government AyA2017-84089 European Commission 776403 Universidad de Valparaiso ; Versión publicada - versión final del editor

Context. The innermost astronomical unit (au) in protoplanetary disks is a key region for stellar and planet formation, as exoplanet searches have shown a large occurrence of close-in planets that are located within the first au around their host star. Aims. We aim to reveal the morphology of the disk inner rim using near-infrared interferometric observations with milli-arcsecond resolution provided by near-infrared multitelescope interferometry. Methods. We provide model-independent reconstructed images of 15 objects selected from the Herbig AeBe survey carried out with PIONIER at the Very Large Telescope Interferometer, using the semi-parametric approach for image reconstruction of chromatic objects. We propose a set of methods to reconstruct and analyze the images in a consistent way. Results. We find that 40% of the systems (6/15) are centrosymmetric at the angular resolution of the observations. For the rest of the objects, we find evidence for asymmetric emission due to moderate-to-strong inclination of a disk-like structure for similar to 30% of the objects (5/15) and noncentrosymmetric morphology due to a nonaxisymmetric and possibly variable environment (4/15, similar to 27%). Among the systems with a disk-like structure, 20% (3/15) show a resolved dust-free cavity. Finally, we do not detect extended emission beyond the inner rim. Conclusions. The image reconstruction process is a powerful tool to reveal complex disk inner rim morphologies, which is complementary to the fit of geometrical models. At the angular resolution reached by near-infrared interferometric observations, most of the images are compatible with a centrally peaked emission (no cavity). For the most resolved targets, image reconstruction reveals morphologies that cannot be reproduced by generic parametric models (e.g., perturbed inner rims or complex brightness distributions). Moreover, the nonaxisymmetric disks show that the spatial resolution probed by optical interferometers makes the observations of the near-infrared emission (inside a few au) sensitive to temporal evolution with a time-scale down to a few weeks. The evidence of nonaxisymmetric emission that cannot be explained by simple inclination and radiative transfer effects requires alternative explanations, such as a warping of the inner disks. Interferometric observations can therefore be used to follow the evolution of the asymmetry of those disks at an au or sub-au scale. ; French National Research Agency (ANR) ANR-10-BLAN-0511 European Union (EU) SH-06192 Philip Leverhulme Prize PLP-2013-110 KU Leuven C14/17/082 National Science Foundation (NSF) 1210972 1616483 European Research Council (ERC) 639889 European Union (EU) 284405 French National Research Agency (ANR) ANR-16-CE31-0013 Australian Research Council FT170100040 DP180104235 Universite Joseph Fourier (UJF, Grenoble) through its Pole TUNES Universite Joseph Fourier (UJF, Grenoble) through its Pole SMING Institut de Planetologie et d'Astrophysique de Grenoble French National Research Agency (ANR) French National Research Agency (ANR) Institut National des Science de l'Univers (INSU) via the "Programme National de Physique Stellaire" Institut National des Science de l'Univers (INSU) via "Programme National de Planetologie"

Context. The mechanisms governing the opening of cavities in transition disks are not fully understood. Several processes have been proposed, but their occurrence rate is still unknown. Aims. We present spatially resolved observations of two transition disks, and aim at constraining their vertical and radial structure using multiwavelength observations that probe different regions of the disks and can help understanding the origin of the cavities. Methods. We have obtained near-infrared scattered light observations with VLT/SPHERE of the transition disks 2MASS J16083070-3828268 (J1608) and RXJ1852.3-3700 (J1852), located in the Lupus and Corona Australis star-forming regions respectively. We complement our datasets with archival ALMA observations, and with unresolved photometric observations covering a wide range of wavelengths. We performed radiative transfer modeling to analyze the morphology of the disks, and then compare the results with a sample of 20 other transition disks observed with both SPHERE and ALMA. Results. We detect scattered light in J1608 and J1852 up to a radius of 0.54 '' and 0.4 '' respectively. The image of J1608 reveals a very inclined disk (i similar to 74 degrees), with two bright lobes and a large cavity. We also marginally detect the scattering surface from the rearfacing side of the disk. J1852 shows an inner ring extending beyond the coronagraphic radius up to 15 au, a gap and a second ring at 42 au. Our radiative transfer model of J1608 indicates that the millimeter-sized grains are less extended vertically and radially than the micron-sized grains, indicating advanced settling and radial drift. We find good agreement with the observations of J1852 with a similar model, but due to the low inclination of the system, the model remains partly degenerate. The analysis of 22 transition disks shows that, in general, the cavities observed in scattered light are smaller than the ones detected at millimeter wavelengths. Conclusions. The analysis of a sample of transition disks indicates that the small grains, well coupled to the gas, can flow inward of the region where millimeter grains are trapped. While 15 out of the 22 cavities in our sample could be explained by a planet of less than 13 Jupiter masses, the others either require the presence of a more massive companion or of several low-mass planets. ; ANR of France [ANR-16-CE31-0013]; European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme [757957]; ICM (Iniciativa Cientifica Milenio) via the Nucleo Milenio de Formacion Planetaria grant; Universidad de Valparaiso; Fondecyt [1180395]; CONICYT [Basal AFB-170002]; FONDECYT Iniciacion project [11181068]; CONICYT + PAI/Convocatoria nacional subvencion a la instalacion en la academia [2017 + Folio PAI77170087]; Spanish MINECO [AyA2017-84089]; ESO; CNRS (France); MPIA (Germany); INAF (Italy); FINES (Switzerland); NOVA (Netherlands); European Commission [RII3-Ct-2004-001566, 226604, 312430]; Programme National de Planetologie (PNP) of CNRS-INSU in France; Programme National de Physique Stellaire (PNPS) of CNRS-INSU in France; French Labex OSUG2020 (Investissements d'avenir) [ANR10 LABX56]; CNRS, by the Agence Nationale de la Recherche [ANR-14-CE33-0018]; Swiss National Science Foundation (SNSF); SNSF ; Open access journal. ; This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.

Context. A large portion of stars is found to be part of binary or higher-order multiple systems. The ubiquity of planets found around single stars raises the question of whether and how planets in binary systems form. Protoplanetary disks are the birthplaces of planets, and characterizing them is crucial in order to understand the planet formation process. Aims. Our goal is to characterize the morphology of the GG Tau A disk, one of the largest and most massive circumbinary disks. We also aim to trace evidence for binary-disk interactions. Methods. We obtained observations in polarized scattered light of GG Tau A using the SPHERE/IRDIS instrument in the H-band filter. We analyzed the observed disk morphology and substructures. We ran 2D hydrodynamical models to simulate the evolution of the circumbinary ring over the lifetime of the disk. Results. The disk and also the cavity and the inner region are highly structured, with several shadowed regions, spiral structures, and streamer-like filaments. Some of these are detected here for the first time. The streamer-like filaments appear to connect the outer ring with the northern arc. Their azimuthal spacing suggests that they may be generated through periodic perturbations by the binary, which tear off material from the inner edge of the outer disk once during each orbit. By comparing observations to hydrodynamical simulations, we find that the main features, in particular, the gap size, but also the spiral and streamer filaments, can be qualitatively explained by the gravitational interactions of a binary with a semimajor axis of similar to 35 au on an orbit coplanar with the circumbinary ring. ; European Research Council under the Horizon 2020 Framework Program via the ERC Advanced Grant Origins 83 24 28 French National Research Agency (ANR) ANR-16-CE31-0013 Australian Research Council FT170100040 DP180104235 European Union's Horizon 2020 research and innovation programme under the Marie Skodowska-Curie grant 823823 Comisión Nacional de Investigación Científica y Tecnológica (CONICYT) CONICYT FONDECYT 11190837 ESO Centre National de la Recherche Scientifique (CNRS) MPIA (Germany) Istituto Nazionale Astrofisica (INAF) FINES (Switzerland) NOVA (The Netherlands) European Union (EU) RII3-Ct2004-001566 European Union (EU) 226604 312430