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Astronomy and Astrophysics 586 (2016): A11 Reproduced with permission from Astronomy & Astrophysics ; Spatially resolving the inner dust cavity (or gap) of the so-called (pre-)transitional disks is a key to understanding the connection between the processes of planetary formation and disk dispersal. The disk around the Herbig star HD 139614 is of particular interest since it presents a pretransitional nature with an au-sized gap structure that is spatially resolved by mid-infrared interferometry in the dust distribution. With the aid of new near-infrared interferometric observations, we aim to characterize the 0.1-10 au region of the HD 139614 disk further and then identify viable mechanisms for the inner disk clearing. We report the first multiwavelength modeling of the interferometric data acquired on HD 139614 with the VLTI instruments PIONIER, AMBER, and MIDI, complemented by Herschel/PACS photometric measurements. We first performed a geometrical modeling of the new near-infrared interferometric data, followed by radiative transfer modeling of the complete dataset using the code RADMC3D. We confirm the presence of a gap structure in the warm μm-sized dust distribution, extending from about 2.5 au to 6 au, and constrained the properties of the inner dust component: e.g., a radially increasing dust surface density profile, and a depletion in dust of ∼103 relative to the outer disk. Since self-shadowing and photoevaporation appears unlikely to be responsible for the au-sized gap of HD 139614, we thus tested if dynamical clearing could be a viable mechanism using hydrodynamical simulations to predict the structure of the gaseous disk. Indeed, a narrow au-sized gap is consistent with the expected effect of the interaction between a single giant planet and the disk. Assuming that small dust grains are well coupled to the gas, we found that an approximately 3 Mjup planet located at ∼4.5 au from the star could, in less than 1 Myr, reproduce most of the aspects of the dust surface density profile, while no significant depletion (in gas) occurred in the inner disk, in contrast to the dust. However, this "dust-depleted" inner disk could be explained by the expected dust filtration by the gap and the efficient dust growth/fragmentation occurring in the inner disk regions. Our results support the hypothesis of a giant planet opening a gap and shaping the inner region of the HD 139614 disk. This makes HD 139614 an exciting candidate specifically for witnessing planet-disk interaction. ; Matter acknowledges financial support from the Centre National d'Études Spatiales (CNES). J.-F. Gonzalez is grateful to the LABEX Lyon Institute of Origins (ANR-10-LABX-0066) of the Université de Lyon for its financial support within the program "Investissements d'Avenir" (ANR-11-IDEX-0007) of the French government operated by the ANR. This work is supported by the French ANR POLCA project (Processing of polychromatic interferometric data for Astrophysics, ANR-10-BLAN-0511)

Context. While exoplanets are now routinely detected, the detection of small bodies in extrasolar systems remains challenging. Since the discovery of sporadic events, which are interpreted to be exocomets (falling evaporating bodies) around β Pic in the early 1980s, only ∼20 stars have been reported to host exocomet-like events. Aims. We aim to expand the sample of known exocomet-host stars, as well as to monitor the hot-gas environment around stars with previously known exocometary activity. Methods. We have obtained high-resolution optical spectra of a heterogeneous sample of 117 main-sequence stars in the spectral type range from B8 to G8. The data were collected in 14 observing campaigns over the course of two years from both hemispheres. We analysed the Ca » II K&H and Na » I D lines in order to search for non-photospheric absorptions that originated in the circumstellar environment and for variable events that could be caused by the outgassing of exocomet-like bodies. Results. We detected non-photospheric absorptions towards 50% of the sample, thus attributing a circumstellar origin to half of the detections (i.e. 26% of the sample). Hot circumstellar gas was detected in the metallic lines inspected via narrow stable absorptions and/or variable blue- and red-shifted absorption events. Such variable events were found in 18 stars in the Ca » II and/or Na » I lines; six of them are reported in the context of this work for the first time. In some cases, the variations we report in the Ca » II K line are similar to those observed in β Pic. While we do not find a significant trend in the age or location of the stars, we do find that the probability of finding CS gas in stars with larger v sin i is higher. We also find a weak trend with the presence of near-infrared excess and with anomalous (λ Boo-like) abundances, but this would require confirmation by expanding the sample. ; With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)

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 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.