Browsing by Author "Williams, J.P."

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    Discovery of a planetary-mass companion within the gap of the transition disk around PDS 70
    (EDP Sciences, 2018) Keppler, M.; Benisty, M.; Müller, 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, M.; Juhasz, A.; Kemmer, J.; Kral, Q.; Lagrange, A.-M.; Launhardt, R.; Matter, A.; Ménard, F.; Milli, J.; Mollière, P.; Olofsson, J.; Pérez, 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.; Delboulbé, 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.; Möller-Nilsson, O.; Moulin, T.; Mugnier, L.; Origné, A.; Pavlov, A.; Perret, D.; Petit, C.; Pragt, J.; Puget, P.; Rabou, P.; Ramos, 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.
    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 (~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 ~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 ~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.
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    High-contrast imaging of HD 163296 with the Keck/NIRC2 L′-band vortex coronograph
    (Oxford University Press, 2018) Guidi, G.; Ruane, G.; Williams, J.P.; Mawet, D.; Testi, L.; Zurlo, A.; Absil, O.; Bottom, M.; Choquet, E.; Christiaens, V.; Castellá, B. Femenía; Huby, E.; Isella, A.; Kastner, J.; Meshkat, T.; Reggiani, M.; Riggs, A.; Serabyn, E.; Wallack, N.
    We present observations of the nearby (D∼100 pc) Herbig star HD 163296 taken with the vortex coronograph at Keck/NIRC2 in the L′ band (3.7 μμm) to search for planetary mass companions in the ringed disc surrounding this pre-main-sequence star. The images reveal an arc-like region of scattered light from the disc surface layers that is likely associated with the first bright ring detected with ALMA in the λ = 1.3 mm dust continuum at ∼65 au. We also detect a point-like source at ∼0.5 arcsec projected separation in the north-east direction, close to the inner edge of the second gap in the millimetre images. Comparing the point source photometry with the atmospheric emission models of non-accreting giant planets, we obtain a mass of 6–7 MJ for a putative protoplanet, assuming a system age of 5 Myr. Based on the contrast at a 95 per cent level of completeness calculated on the emission-free regions of our images, we set upper limits for the masses of giant planets of 8–15 MJ, 4.5–6.5 MJ, and 2.5–4.0 MJ at the locations of the first, second, and third gap in the millimetre dust continuum, respectively. Further deep, high-resolution thermal IR imaging of the HD 163296 system are warranted to confirm the presence and nature of the point source and to better understand the structure of the dust disc.