The GJ 504 system revisited. Combining interferometric, radial velocity, and high contrast imaging data
Creators: name: Bonnefoy, M.
name: Perraut, K.
name: Lagrange, A. -M.
name: Delorme, P.
name: Vigan, A.
name: Line, M.
name: Rodet, L.
name: Ginski, C.
name: Mourard, D.
name: Marleau, G. -D.
name: Samland, M.
name: Tremblin, P.
name: Ligi, R.
name: Cantalloube, F.
name: Mollière, P.
name: Charnay, B.
name: Kuzuhara, M.
name: Janson, M.
name: Morley, C.
name: Homeier, D. D.
name: Orazi, V. D
name: Klahr, H.
name: Mordasini, C.
name: Lavie, B.
name: Baudino, J. -L.
name: Beust, H.
name: Peretti, S.
name: Bartucci, A. Musso
name: Mesa, D.
name: Bézard, B.
name: Boccaletti, A.
name: Galicher, R.
name: Hagelberg, J.
name: Desidera, S.
name: Biller, B.
name: Maire, A. -L.
name: Allard, F.
name: Borgniet, S.
name: Lannier, J.
name: Meunier, N.
name: Desort, M.
name: Alecian, E.
name: Chauvin, G.
name: Langlois, M.
name: Henning, T.
name: Mugnier, L.
name: Mouillet, D.
name: Gratton, R.
name: Brandt, T.
name: Elwain, M. Mc
name: Beuzit, J. -L.
name: Tamura, M.
name: Hori, Y.
name: Brandner, W.
name: Buenzli, E.
name: Cheetham, A
name: Cudel, M.
name: Feldt, M.
name: Kasper, M.
name: Keppler, M.
name: Kopytova, T.
name: Meyer, M.
name: Perrot, C.
name: Rouan, D.
name: Salter, G
name: Schmidt, T.
name: Sissa, E.
name: Zurlo, A.
name: Wildi, F.
name: Blanchard, P.
name: De Caprio, V.
name: Delboulbé, A.
name: Maurel, D.
name: Moulin, T.
name: Pavlov, A.
name: Rabou, P.
name: Ramos, J.
name: Roelfsema, R.
name: Rousset, G.
name: Stadler, E.
name: Rigal, F.
name: Weber, L.
Publisher: name: arXiv
Year: 2018
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: The G-type star GJ504A is known to host a 3 to 35 MJup companion whose temperature, mass, and projected separation all contribute to make it a test case for the planet formation theories and for atmospheric models of giant planets and light brown dwarfs. We collected data from the CHARA interferometer, SOPHIE spectrograph, and VLT/SPHERE high contrast imager to revisit the properties of the system. We measure a radius of 1.35+/- 0.04Rsun for GJ504A which yields isochronal ages of 21+/-2Myr or 4.0+/-1.8Gyr for the system and line-of-sight stellar rotation axis inclination of $162.4_{-4.3}^{+3.8}$ degrees or $18.6_{-3.8}^{+4.3}$ degrees. We re-detect the companion in the Y2, Y3, J3, H2, and K1 dual band SPHERE images. The complete 1-4 $μ$m SED shape of GJ504b is best reproduced by T8-T9.5 objects with intermediate ages ($\leq1.5$Gyr), and/or unusual dusty atmospheres and/or super-solar metallicities. All six atmospheric models used yield $\mathrm{T_{eff}=550 \pm 50}$K for GJ504b and point toward a low surface gravity (3.5-4.0 dex). The accuracy on the metallicity value is limited by model-to-model systematics. It is not degenerate with the C/O ratio. We derive $\mathrm{log\:L/L_{\odot}=-6.15\pm0.15}$ dex for the companion compatible with masses of $\mathrm{M=1.3^{+0.6}_{-0.3}M_{Jup}}$ and $\mathrm{M=23^{+10}_{-9} M_{Jup}}$ for the young and old age ranges, respectively. The semi-major axis (sma) is above 27.8 au and the eccentricity lower than 0.55. The posterior on GJ~504b's orbital inclination suggests a misalignment with GJ~504A rotation axis. We combine the radial velocity and multi-epoch imaging data to exclude additional objects (90\% prob.) more massive than 2.5 and 30 $\mathrm{M_{Jup}}$ with sma in the range 0.01-80 au for the young and old system ages, respectively. The companion is in the envelope of the population of planets synthetized with our core-accretion model.
description: 33 pages, 25 figures. Accepted in Astronomy and Astrophysics