Suchergebnisse

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.