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Photodynamical mass determination of the multiplanetary system K2-19

S. C. C. Barros, J.-M. Almenara, O. Demangeon, M. Tsantaki, A. Santerne, D. J. Armstrong, D. Barrado-Navascues, D. Brown, M. Deleuil, J. Lillo Box, H. P. Osborn, D. Pollacco, L. Abe, P. AndrÚ, P. Bendjoya, I. Boisse, A. S. Bonomo, F. Bouchy, G. Bruno, J. Rey Cerda, B. Courcol, R. F. DÝaz, G. HÚbrard, J. Kirk, J. C. LachuriÚ, K. W. F. Lam, P. Martinez, J. McCormac, C. Moutou, A. S. Rajpurohit, J.-P. Rivet, J. Spake, O. Suarez, D. Toublanc, S. R. Walker

Abstract
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 Mb = 44 ± 12  M and Mc = 15.9 ± 7.0  M 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.

Keywords
techniques: photometric - techniques: radial velocities - time - planets and satellites: detection - planets and satellites: dynamical evolution and stability - planets and satellites: individual: EPIC201505350, K2-19

Monthly Notices of the Royal Astronomical Society
Volume 454, Issue 4, Page 4267
2015 December

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Instituto de Astrof├şsica e Ci├¬ncias do Espa├žo Universidade do Porto Faculdade de Ciências da Universidade de Lisboa Funda├ž├úo para a Ci├¬ncia e a Tecnologia
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