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  • 1. D'Orazi, V.
    et al.
    Gratton, R.
    Desidera, S.
    Avenhaus, H.
    Mesa, D.
    Stolker, T.
    Giro, E.
    Benatti, S.
    Jang-Condell, H.
    Rigliaco, E.
    Sissa, E.
    Scatolin, T.
    Benisty, M.
    Bhowmik, T.
    Boccaletti, A.
    Bonnefoy, M.
    Brandner, W.
    Buenzli, E.
    Chauvin, G.
    Daemgen, S.
    Damasso, M.
    Feldt, M.
    Galicher, R.
    Girard, J.
    Janson, Markus
    Stockholm University, Faculty of Science, Department of Astronomy.
    Hagelberg, J.
    Mouillet, D.
    Kral, Q.
    Lanniers, J.
    Lagrange, A-M
    La Nglois, M.
    Maire, A-L
    Menard, F.
    Moeller-Nilsson, O.
    Perrot, C.
    Peretti, S.
    Rabou, P.
    Ramos, J.
    Rodet, L.
    Roelfsema, R.
    Roux, A.
    Salter, G.
    Schlieder, J. E.
    Schmidt, T.
    Szulagyi, J.
    Thalmann, C.
    Thebault, P.
    van der Plas, G.
    Vigan, A.
    Zurlo, A.
    Mapping of shadows cast on a protoplanetary disk by a close binary system2019In: Nature astronomy, ISSN 2397-3366, Vol. 3, no 2, p. 167-172Article in journal (Refereed)
    Abstract [en]

    For a comprehensive understanding of planetary formation and evolution, we need to investigate the environment in which planets form: circumstellar disks. Here we present high-contrast imaging observations of V4046 Sagittarii, a 20-Myr-old close binary known to host a circumbinary disk. We have discovered the presence of rotating shadows in the disk, caused by mutual occultations of the central binary. Shadow-like features are often observed in disks(1,2), but those found thus far have not been due to eclipsing phenomena. We have used the phase difference due to light travel time to measure the flaring of the disk and the geometrical distance of the system. We calculate a distance that is in very good agreement with the value obtained from the Gaia mission's Data Release 2 (DR2), and flaring angles of alpha = (6.2 +/- 0.6)degrees and alpha = (8.5 +/- 1.0)degrees for the inner and outer disk rings, respectively. Our technique opens up a path to explore other binary systems, providing an independent estimate of distance and the flaring angle, a crucial parameter for disk modelling.

  • 2. Keppler, M.
    et al.
    Benisty, M.
    Mueller, A.
    Henning, Th.
    van Boekel, R.
    Cantalloube, F.
    Ginski, C.
    van Holstein, R. G.
    Maire, A. -L.
    Pohl, A.
    Samland, M.
    Avenhaus, H.
    Baudino, J. -L.
    Boccaletti, A.
    de Boer, J.
    Bonnefoy, M.
    Chauvin, G.
    Desidera, S.
    Langlois, M.
    Lazzoni, C.
    Marleau, G. -D.
    Mordasini, C.
    Pawellek, N.
    Stolker, T.
    Vigan, A.
    Zurlo, A.
    Birnstiel, T.
    Brandner, W.
    Feldt, M.
    Flock, M.
    Girard, J.
    Gratton, R.
    Hagelberg, J.
    Isella, A.
    Janson, Markus
    Stockholm University, Faculty of Science, Department of Astronomy. Max Planck Institute for Astronomy, Germany.
    Juhasz, A.
    Kemmer, J.
    Kral, Q.
    Lagrange, A. -M.
    Launhardt, R.
    Matter, A.
    Menard, F.
    Milli, J.
    Molliere, P.
    Olofsson, J.
    Perez, L.
    Pinilla, P.
    Pinte, C.
    Quanz, S. P.
    Schmidt, T.
    Udry, S.
    Wahhaj, Z.
    Williams, J. P.
    Buenzli, E.
    Cudel, M.
    Dominik, C.
    Galicher, R.
    Kasper, M.
    Lannier, J.
    Mesa, D.
    Mouillet, D.
    Peretti, S.
    Perrot, C.
    Salter, G.
    Sissa, E.
    Wildi, F.
    Abe, L.
    Antichi, J.
    Augereau, J. -C.
    Baruffolo, A.
    Baudoz, P.
    Bazzon, A.
    Beuzit, J. -L.
    Blanchard, P.
    Brems, S. S.
    Buey, T.
    De Caprio, V.
    Carbillet, M.
    Carle, M.
    Cascone, E.
    Cheetham, A.
    Claudi, R.
    Costille, A.
    Delboulbe, A.
    Dohlen, K.
    Fantinel, D.
    Feautrier, P.
    Fusco, T.
    Giro, E.
    Gluck, L.
    Gry, C.
    Hubin, N.
    Hugot, E.
    Jaquet, M.
    Le Mignant, D.
    Llored, M.
    Madec, F.
    Magnard, Y.
    Martinez, P.
    Maurel, D.
    Meyer, M.
    Moeller-Nilsson, O.
    Moulin, T.
    Mugnier, L.
    Origne, A.
    Pavlov, A.
    Perret, D.
    Petit, C.
    Pragt, J.
    Puget, P.
    Rabou, P.
    Ramose, J.
    Rigal, F.
    Rochat, S.
    Roelfsema, R.
    Rousset, G.
    Roux, A.
    Salasnich, B.
    Sauvage, J. -F.
    Sevin, A.
    Soenke, C.
    Stadler, E.
    Suarez, M.
    Turatto, M.
    Weber, L.
    Discovery of a planetary-mass companion within the gap of the transition disk around PDS 702018In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 617, article id A44Article in journal (Refereed)
    Abstract [en]

    Context. Young circumstellar disks are the birthplaces of planets. Their study is of prime interest to understand the physical and chemical conditions under which planet formation takes place. Only very few detections of planet candidates within these disks exist, and most of them are currently suspected to be disk features.

    Aims. In this context, the transition disk around the young star PDS 70 is of particular interest, due to its large gap identified in previous observations, indicative of ongoing planet formation. We aim to search for the presence of an embedded young planet and search for disk structures that may be the result of disk-planet interactions and other evolutionary processes.

    Methods. We analyse new and archival near-infrared images of the transition disk PDS 70 obtained with the VLT/SPHERE, VLT/NaCo, and Gemini/NICI instruments in polarimetric differential imaging and angular differential imaging modes.

    Results. We detect a point source within the gap of the disk at about 195 mas (similar to 22 au) projected separation. The detection is confirmed at five different epochs, in three filter bands and using different instruments. The astrometry results in an object of bound nature, with high significance. The comparison of the measured magnitudes and colours to evolutionary tracks suggests that the detection is a companion of planetary mass. The luminosity of the detected object is consistent with that of an L-type dwarf, but its IR colours are redder, possibly indicating the presence of warm surrounding material. Further, we confirm the detection of a large gap of similar to 54 au in size within the disk in our scattered light images, and detect a signal from an inner disk component. We find that its spatial extent is very likely smaller than similar to 17 au in radius, and its position angle is consistent with that of the outer disk. The images of the outer disk show evidence of a complex azimuthal brightness distribution which is different at different wavelengths and may in part be explained by Rayleigh scattering from very small grains.

    Conclusions. The detection of a young protoplanet within the gap of the transition disk around PDS 70 opens the door to a so far observationally unexplored parameter space of planetary formation and evolution. Future observations of this system at different wavelengths and continuing astrometry will allow us to test theoretical predictions regarding planet-disk interactions, planetary atmospheres, and evolutionary models.

  • 3. Ligi, R.
    et al.
    Vigan, A.
    Gratton, R.
    de Boer, J.
    Benisty, M.
    Boccaletti, A.
    Quanz, S. P.
    Meyer, M.
    Ginski, C.
    Sissa, E.
    Gry, C.
    Henning, T.
    Beuzit, J. -L.
    Biller, B.
    Bonnefoy, M.
    Chauvin, G.
    Cheetham, A. C.
    Cudel, M.
    Delorme, P.
    Desidera, S.
    Feldt, M.
    Galicher, R.
    Girard, J.
    Janson, Markus
    Stockholm University, Faculty of Science, Department of Astronomy.
    Kasper, M.
    Kopytova, T.
    Lagrange, A. -M.
    Langlois, M.
    Lecoroller, H.
    Maire, A. -L.
    Menard, F.
    Mesa, D.
    Peretti, S.
    Perrot, C.
    Pinilla, P.
    Pohl, A.
    Rouan, D.
    Stolker, T.
    Samland, M.
    Wahhaj, Z.
    Wildi, F.
    Zurlo, A.
    Buey, T.
    Fantinel, D.
    Fusco, T.
    Jaquet, M.
    Moulin, T.
    Ramos, J.
    Suarez, M.
    Weber, L.
    Investigation of the inner structures around HD 169142 with VLT/SPHERE2018In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 473, no 2, p. 1774-1783Article in journal (Refereed)
    Abstract [en]

    We present observations of the Herbig Ae star HD 169142 with the VLT/SPHERE instruments InfraRed Dual-band Imager and Spectrograph (IRDIS) (K1K2 and H2H3 bands) and the Integral Field Spectrograph (IFS) (Y, J and H bands). We detect several bright blobs at similar to 180 mas separation from the star, and a faint arc-like structure in the IFS data. Our reference differential imaging (RDI) data analysis also finds a bright ring at the same separation. We show, using a simulation based on polarized light data, that these blobs are actually part of the ring at 180 mas. These results demonstrate that the earlier detections of blobs in the H and K-S bands at these separations in Biller et al. as potential planet/substellar companions are actually tracing a bright ring with a Keplerian motion. Moreover, we detect in the images an additional bright structure at similar to 93 mas separation and position angle of 355 degrees, at a location very close to previous detections. It appears point-like in the YJ and K bands but is more extended in the H band. We also marginally detect an inner ring in the RDI data at similar to 100 mas. Follow-up observations are necessary to confirm the detection and the nature of this source and structure.

  • 4. Mueller, A.
    et al.
    Keppler, M.
    Henning, Th.
    Samland, M.
    Chauvin, G.
    Beust, H.
    Maire, A. -L.
    Molaverdikhani, K.
    van Boekel, R.
    Benisty, M.
    Boccaletti, A.
    Bonnefoy, M.
    Cantalloube, F.
    Charnay, B.
    Baudino, J. -L.
    Gennaro, M.
    Long, Z. C.
    Cheetham, A.
    Desidera, S.
    Feldt, M.
    Fusco, T.
    Girard, J.
    Gratton, R.
    Hagelberg, J.
    Janson, Markus
    Stockholm University, Faculty of Science, Department of Astronomy. Max Planck Institute for Astronomy, Germany.
    Lagrange, A. -M.
    Langlois, M.
    Lazzoni, C.
    Ligi, R.
    Menard, F.
    Mesa, D.
    Meyer, M.
    Molliere, P.
    Mordasini, C.
    Moulin, T.
    Pavlov, A.
    Pawellek, N.
    Quanz, S. P.
    Ramos, J.
    Rouan, D.
    Sissa, E.
    Stadler, E.
    Vigan, A.
    Wahhaj, Z.
    Weber, L.
    Zurlo, A.
    Orbital and atmospheric characterization of the planet within the gap of the PDS70 transition disk2018In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 617, article id L2Article in journal (Refereed)
    Abstract [en]

    Context. The observation of planets in their formation stage is a crucial but very challenging step in understanding when, how, and where planets form. PDS 70 is a young pre-main sequence star surrounded by a transition disk, in the gap of which a planetary-mass companion has recently been discovered. This discovery represents the first robust direct detection of such a young planet, possibly still at the stage of formation.

    Aims. We aim to characterize the orbital and atmospheric properties of PDS 70 b, which was first identified on May 2015 in the course of the SHINE survey with SPHERE, the extreme adaptive-optics instrument at the VLT.

    Methods. We obtained new deep SPHERE/IRDIS imaging and SPHERE/IFS spectroscopic observations of PDS 70 b. The astrometric baseline now covers 6 yr, which allowed us to perform an orbital analysis. For the first time, we present spectrophotometry of the young planet which covers almost the entire near-infrared range (0.96-3.8 mu m). We use different atmospheric models covering a large parameter space in temperature, log g, chemical composition, and cloud properties to characterize the properties of the atmosphere of PDS 70 b.

    Results. PDS 70 b is most likely orbiting the star on a circular and disk coplanar orbit at similar to 22 au inside the gap of the disk. We find a range of models that can describe the spectrophotometric data reasonably well in the temperature range 1000-1600 K and log g no larger than 3.5 dex. The planet radius covers a relatively large range between 1.4 and 3.7 R-J with the larger radii being higher than expected from planet evolution models for the age of the planet of 5.4 Myr.

    Conclusions. This study provides a comprehensive data set on the orbital motion of PDS 70 b, indicating a circular orbit and a motion coplanar with the disk. The first detailed spectral energy distribution of PDS 70 b indicates a temperature typical of young giant planets. The detailed atmospheric analysis indicates that a circumplanetary disk may contribute to the total planetflux.

  • 5. Rodet, L.
    et al.
    Bonnefoy, M.
    Durkan, Stephen
    Stockholm University, Faculty of Science, Department of Astronomy. Queens University Belfast, UK.
    Beust, H.
    Lagrange, A. -M.
    Schlieder, J. E.
    Janson, Markus
    Stockholm University, Faculty of Science, Department of Astronomy.
    Grandjean, A.
    Chauvin, G.
    Messina, S.
    Maire, A. -L.
    Brandner, W.
    Girard, J.
    Delorme, P.
    Biller, B.
    Bergfors, C.
    Lacour, S.
    Feldt, M.
    Henning, T.
    Boccaletti, A.
    Le Bouquin, J. -B.
    Berger, J. -P.
    Monin, J. -L.
    Udry, S.
    Peretti, S.
    Segransan, D.
    Allard, F.
    Homeier, D.
    Vigan, A.
    Langlois, M.
    Hagelberg, J.
    Menard, F.
    Bazzon, A.
    Beuzit, J. -L.
    Delboulbe, A.
    Desidera, S.
    Gratton, R.
    Lannier, J.
    Ligi, R.
    Maurel, D.
    Mesa, D.
    Meyer, M.
    Pavlov, A.
    Ramos, J.
    Rigal, R.
    Roelfsema, R.
    Salter, G.
    Samland, M.
    Schmidt, T.
    Stadler, E.
    Weber, L.
    Dynamical masses of M-dwarf binaries in young moving groups I. The case of TWA22 and GJ20602018In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 618, article id A23Article in journal (Refereed)
    Abstract [en]

    Context. Evolutionary models are widely used to infer the mass of stars, brown dwarfs, and giant planets. Their predictions are thought to be less reliable at young ages (<200 Myr) and in the low-mass regime (< 1 M-circle dot). GJ 2060AB and TWA22AB are two rare astrometric M-dwarf binaries, respectively members of the AB Doradus (AB Dor) and Beta Pictoris (beta Pic) moving groups. As their dynamical mass can be measured to within a few years, they can be used to calibrate the evolutionary tracks and set new constraints on the age of young moving groups.

    Aims. We provide the first dynamical mass measurement of GJ 2060 and a refined measurement of the total mass of TWA22. We also characterize the atmospheric properties of the individual components of GJ 2060 that can be used as inputs to the evolutionary models.

    Methods. We used NaCo and SPHERE observations at VLT and archival Keck/NIRC2 data to complement the astrometric monitoring of the binaries. We combined the astrometry with new HARPS radial velocities (RVs) and FEROS RVs of GJ 2060. We used a Markov chain MonteCarlo (MCMC) module to estimate posteriors on the orbital parameters and dynamical masses of GJ 2060AB and TWA22AB from the astrometry and RVs. Complementary data obtained with the integral field spectrograph VLT /SINFONI were gathered to extract the individual near-infrared (1.1-2.5 mu m) medium-resolution (R similar to 1500 2000) spectra of GJ 2060A and B. We compared the spectra to those of known objects and to grids of BT-SETTL model spectra to infer the spectral type, bolometric luminosities, and temperatures of those objects.

    Results. We find a total mass of 0 : 18 +/- 0 : 02 M-circle dot for TWA22, which is in good agreement with model predictions at the age of the fi Pic moving group. We obtain a total mass of 1 : 09 +/- 0 : 10 M-circle dot for GJ 2060. We estimate a spectral type of M1 +/- 0.5, L/L-circle dot = -1.20 +/- 0.05 dex, and T-eff = 3700 +/- 100 K for GJ 2060 A. The B component is a M3 +/- 0 : 5 dwarf with L/L-circle dot = 1.63 +/- 0.05 dex and T-eff = 3400 +/- 100 K. The dynamical mass of GJ 2060AB is inconsistent with the most recent models predictions (BCAH15, PARSEC) for an AB Dor age in the range 50-150 Myr. It is 10%-20% (1-2 sigma, depending on the assumed age) above the model's predictions, corresponding to an underestimation of 0.10-0.20 M fi. Coevality suggests a young age for the system (similar to 50 Myr) according to most evolutionary models.

    Conclusions. TWA22 validates the predictions of recent evolutionary tracks at similar to 20 Myr. On the other hand, we evidence a 1-2 sigma mismatch between the predicted and observed mass of GJ 2060 AB. This slight departure may indicate that one of the stars hosts a tight companion. Alternatively, this would confirm the model's tendency to underestimate the mass of young low-mass stars.

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