Discovery of a warm, dusty giant planet around HIP 65426

G. Chauvin, S. Desidera, A. -M. Lagrange, A. Vigan, R. Gratton, M. Langlois, M. Bonnefoy, J. -L. Beuzit, M. Feldt, D. Mouillet, M. Meyer, A. Cheetham, B. Biller, A. Boccaletti, V. D'Orazi, R. Galicher, J. Hagelberg, A. -L. Maire, D. Mesa, J. OlofssonM. Samland, T. O. B. Schmidt, E. Sissa, M. Bonavita, B. Charnay, M. Cudel, S. Daemgen, P. Delorme, P. Janin-Potiron, M. Janson, M. Keppler, H. Le Coroller, R. Ligi, G. D. Marleau, S. Messina, P. Molliere, C. Mordasini, A. Muller, S. Peretti, C. Perrot, L. Rodet, D. Rouan, A. Zurlo, C. Dominik, T. Henning, F. Menard, H. -M. Schmid, M. Turatto, S. Udry, F. Vakili, L. Abe, J. Antichi, A. Baruffolo, P. Baudoz, J. Baudrand, P. Blanchard, A. Bazzon, T. Buey, M. Carbillet, M. Carle, J. Charton, E. Cascone, R. Claudi, A. Costille, A. Deboulbe, V. De Caprio, K. Dohlen, D. Fantinel, P. Feautrier, T. Fusco, P. Gigan, E. Giro, D. Gisler, L. Gluck, N. Hubin, E. Hugot, M. Jaquet, M. Kasper, F. Madec, Y. Magnard, P. Martinez, D. Maurel, D. Le Mignant, O. Moller-Nilsson, M. Llored, T. Moulin, A. Origné, A. Pavlov, D. Perret, C. Petit, J. Pragt, P. Puget, P. Rabou, J. Ramos, R. Rigal, S. Rochat, R. Roelfsema, G. Rousset, A. Roux, B. Salasnich, J. -F. Sauvage, A. Sevin, C. Soenke, E. Stadler, M. Suarez, L. Weber, F. Wildi, S. Antoniucci, J. -C. Augereau, J. -L. Baudino, W. Brandner, N. Engler, J. Girard, C. Gry, Q. Kral, T. Kopytova, E. Lagadec, J. Milli, C. Moutou, J. Schlieder, J. Szulágyi, C. Thalmann, Z. Wahhaj

Research output: Contribution to journalArticlepeer-review

Abstract

The SHINE program is a large high-contrast near-infrared survey of 600 young, nearby stars. It is aimed at searching for and characterizing new planetary systems using VLT/SPHERE's unprecedented high-contrast and high-angular resolution imaging capabilities. It also intends at placing statistical constraints on the occurrence and orbital properties of the giant planet population at large orbits as a function of the stellar host mass and age to test planet formation theories. We use the IRDIS dual-band imager and the IFS integral field spectrograph of SPHERE to acquire high-constrast coronagraphic differential near-infrared images and spectra of the young A2 star HIP65426. It is a member of the ~17 Myr old Lower Centaurus-Crux association. 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 HIP65426. Spectro-photometric measurements extracted with IFS and IRDIS between 0.95 and 2.2um 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 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). Given its physical and spectral properties, HIP65426b 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.
Original languageEnglish
Article numberL9
Number of pages9
JournalAstronomy & Astrophysics
Volume605
DOIs
Publication statusPublished - 18 Sep 2017

Keywords

  • astro-ph.EP

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