Photodynamical mass determination of the multiplanetary system K2-19

S. C. C. Barros (1) , J. M. Almenara (2) , O. Demangeon (3, 4) , M. Tsantaki , A. Santerne (5) , D. J. Armstrong , D. Barrado (6, 7) , D. Brown (8) , M. Deleuil (2) , J. Lillo-Box , H. Osborn , D. Pollacco , L. Abe (9) , P. André (10) , P. Bendjoya (11) , I. Boisse (2) , A. S. Bonomo , F. Bouchy (12, 13) , G. Bruno , J. Rey Cerda , B. Courcol , R. F. Diaz , G. Hébrard (13) , J. Kirk (14) , J. C. Lachurie , K. W. F. Lam , P. Martinez (15) , J. Mccormac , C. Moutou (16) , A. Rajpurohit , J. -P. Rivet , J. Spake , O. Suarez , D. Toublanc (17) , S. R. Walker

1 Virologia
2 LAM - Laboratoire d'Astrophysique de Marseille
3 UP11 - Université Paris-Sud - Paris 11
4 IAS - Institut d'astrophysique spatiale
5 CAUP - Centro de Astrofísica da Universidade do Porto
6 Departamento de Astrofisica [Madrid]
7 Calar Alto Observatory
8 LPNHE - Laboratoire de Physique Nucléaire et de Hautes Énergies
9 LAGRANGE - Joseph Louis LAGRANGE
10 AIM (UMR7158 / UMR_E_9005 / UM_112) - Astrophysique Interprétation Modélisation
11 COMUE UCA - COMUE Université Côte d'Azur (2015-2019)
12 OHP - Observatoire de Haute-Provence
13 IAP - Institut d'Astrophysique de Paris
14 School of Physics and Astronomy [Cardiff]
15 EPOC - Environnements et Paléoenvironnements OCéaniques
16 CFHT - Canada-France-Hawaii Telescope Corporation
17 CESR - Centre d'étude spatiale des rayonnements

K2-19 is the second multiplanetary system discovered with K2 observations. The system is composed of two Neptune size planets close to the 3: 2 mean-motion resonance. To better characterize the system we obtained two additional transit observations of K2-19b and five additional radial velocity observations. These were combined with K2 data and fitted simultaneously with the system dynamics ( photodynamical model) which increases the precision of the transit time measurements. The higher transit time precision allows us to detect the chopping signal of the dynamic interaction of the planets that in turn permits to uniquely characterize the system. Although the reflex motion of the star was not detected, dynamic modelling of the system allowed us to derive planetary masses of M-b = 44 +/- 12 M-circle plus and M-c = 15.9 +/- 7.0 M-circle plus for the inner and the outer planets, respectively, leading to densities close to Uranus. We also show that our method allows the derivation of mass ratios using only the 80 d of observations during the first campaign of K2.

Domaines: Astrophysique [astro-ph]

S. C. C. Barros, J. M. Almenara, O. Demangeon, M. Tsantaki, A. Santerne, et al.. Photodynamical mass determination of the multiplanetary system K2-19. Monthly Notices of the Royal Astronomical Society, 2015, 454 (4), pp.4267--4276. ⟨10.1093/mnras/stv2271⟩. ⟨hal-01439817⟩