Discovery of a warm, dusty giant planet around HIP 65426
Journal
Date Issued
2017
Author(s)
Chauvin, G.
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Lagrange, A. -M.
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Vigan, A.
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Langlois, M.
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Bonnefoy, M.
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Beuzit, J. -L.
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Feldt, M.
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Mouillet, D.
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Meyer, M.
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Cheetham, A.
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Biller, B.
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Boccaletti, A.
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Galicher, R.
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Hagelberg, J.
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Maire, A. -L.
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Olofsson, J.
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Samland, M.
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Schmidt, T. O. B.
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Sissa, E.
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Bonavita, M.
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Charnay, B.
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Cudel, M.
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Daemgen, S.
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Delorme, P.
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Janin-Potiron, P.
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Janson, M.
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Keppler, M.
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Le Coroller, H.
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Marleau, G. D.
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Mollière, P.
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Mordasini, C.
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Müller, A.
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Peretti, S.
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Perrot, C.
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Rodet, L.
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Rouan, D.
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Zurlo, A.
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Dominik, C.
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Henning, T.
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Menard, F.
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Schmid, H. -M.
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Udry, S.
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Vakili, F.
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Abe, L.
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Antichi, J.
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Baudoz, P.
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Baudrand, J.
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Blanchard, P.
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Bazzon, A.
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Buey, T.
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Carbillet, M.
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Carle, M.
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Charton, J.
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Costille, A.
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Deboulbe, A.
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Dohlen, K.
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Feautrier, P.
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Fusco, T.
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Gigan, P.
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Gisler, D.
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Gluck, L.
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Hubin, N.
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Hugot, E.
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Jaquet, M.
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Kasper, M.
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Madec, F.
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Magnard, Y.
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Martinez, P.
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Maurel, D.
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Le Mignant, D.
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Möller-Nilsson, O.
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Llored, M.
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Moulin, T.
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Origné, A.
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Pavlov, A.
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Perret, D.
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Petit, C.
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Pragt, J.
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Puget, P.
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Rabou, P.
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Ramos, J.
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Rigal, R.
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Rochat, S.
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Roelfsema, R.
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Rousset, G.
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Roux, A.
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Sauvage, J. -F.
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Sevin, A.
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Soenke, C.
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Stadler, E.
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Suarez, M.
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Weber, L.
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Wildi, F.
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Augereau, J. -C.
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Baudino, J. -L.
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Brandner, W.
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Engler, N.
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Girard, J.
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Gry, C.
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Kral, Q.
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Kopytova, T.
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Lagadec, E.
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Milli, J.
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Moutou, C.
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Schlieder, J.
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Szulágyi, J.
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Thalmann, C.
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Wahhaj, Z.
Abstract
Aims: The SHINE program is a high-contrast near-infrared survey of 600 young, nearby stars aimed at searching for and characterizing new planetary systems using VLT/SPHERE's unprecedented high-contrast and high-angular-resolution imaging capabilities. It is also intended to place statistical constraints on the rate, mass and orbital distributions of the giant planet population at large orbits as a function of the stellar host mass and age to test planet-formation theories.
Methods: We used the IRDIS dual-band imager and the IFS integral field spectrograph of SPHERE to acquire high-contrast coronagraphic differential near-infrared images and spectra of the young A2 star HIP 65426. It is a member of the 17 Myr old Lower Centaurus-Crux association. Results: At a separation of 830 mas (92 au projected) from the star, we detect a faint red companion. Multi-epoch observations confirm that it shares common proper motion with HIP 65426. Spectro-photometric measurements extracted with IFS and IRDIS between 0.95 and 2.2 μm indicate a warm, dusty atmosphere characteristic of young low-surface-gravity L5-L7 dwarfs. Hot-start evolutionary models predict a luminosity consistent with a 6-12 MJup, Teff = 1300-1600 K and R = 1.5 ± 0.1 RJup giant planet. Finally, the comparison with Exo-REM and PHOENIX BT-Settl synthetic atmosphere models gives consistent effective temperatures but with slightly higher surface gravity solutions of log (g) = 4.0-5.0 with smaller radii (1.0-1.3 RJup).
Conclusions: Given its physical and spectral properties, HIP 65426 b occupies a rather unique placement in terms of age, mass, and spectral-type among the currently known imaged planets. It represents a particularly interesting case to study the presence of clouds as a function of particle size, composition, and location in the atmosphere, to search for signatures of non-equilibrium chemistry, and finally to test the theory of planet formation and evolution.
Methods: We used the IRDIS dual-band imager and the IFS integral field spectrograph of SPHERE to acquire high-contrast coronagraphic differential near-infrared images and spectra of the young A2 star HIP 65426. It is a member of the 17 Myr old Lower Centaurus-Crux association. Results: At a separation of 830 mas (92 au projected) from the star, we detect a faint red companion. Multi-epoch observations confirm that it shares common proper motion with HIP 65426. Spectro-photometric measurements extracted with IFS and IRDIS between 0.95 and 2.2 μm indicate a warm, dusty atmosphere characteristic of young low-surface-gravity L5-L7 dwarfs. Hot-start evolutionary models predict a luminosity consistent with a 6-12 MJup, Teff = 1300-1600 K and R = 1.5 ± 0.1 RJup giant planet. Finally, the comparison with Exo-REM and PHOENIX BT-Settl synthetic atmosphere models gives consistent effective temperatures but with slightly higher surface gravity solutions of log (g) = 4.0-5.0 with smaller radii (1.0-1.3 RJup).
Conclusions: Given its physical and spectral properties, HIP 65426 b occupies a rather unique placement in terms of age, mass, and spectral-type among the currently known imaged planets. It represents a particularly interesting case to study the presence of clouds as a function of particle size, composition, and location in the atmosphere, to search for signatures of non-equilibrium chemistry, and finally to test the theory of planet formation and evolution.
Based on observations collected at La Silla and Paranal Observatory, ESO (Chile) Program ID: 097.C-0865 and 098.C-0209 (SPHERE).The planet spectrum is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/605/L9
Volume
605
Start page
L9
Issn Identifier
0004-6361
Ads BibCode
2017A&A...605L...9C
Rights
open.access
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