J. Lillo-Box, T. A. Lopez, A. Santerne, L. D. Nielsen, S. C. C. Barros, M. Deleuil, O. Mousis, S. G. Sousa, V. Zh. Adibekyan, D. J. Armstrong, D. Barrado, D. Bayliss, D. J. A. Brown, O. Demangeon, X. Dumusque, P. Figueira, S. Hojjatpanah, H. P. Osborn, N. C. Santos, S. Udry

Abstract
We measure the masses and densities of a four-planet near resonant chain system (K2-32), and a young (~400 Myr old) planetary system consisting of three close-in small planets (K2-233). We find that K2-32 is a compact scaled-down version of the Solar System's architecture, with a small rocky inner planet followed by an inflated Neptune-mass planet and two external sub-Neptunes. K2-32 becomes one of the few multi-planetary systems with four or more planets known with measured masses and radii. Additionally, we constrain the masses of the three planets in K2-233. For the two inner Earth-size planets we constrain their masses to be smaller than Mb<11.3 M_⊕, Mc<12.8 M_⊕. The outer planet is a sub-Neptune size planet with an inferred mass of Md=8.3^+5.2_-4.7 M_⊕ (Md<21.1 M_⊕). Our observations confirm for the first time the rocky nature of two planets orbiting a young star, with relatively short orbital periods (<7 days). They K2-233 provide key information for planet formation and evolution models of telluric planets. Additionally, the Neptune-like derived masses of the three planets K2-32 b, c, d puts them in a relatively unexplored regime of incident flux and planet mass, key for transmission spectroscopy studies.

Contributions to the XIV.0 Scientific Meeting (virtual) of the Spanish Astronomical Society

Volume XIV, Number 103
2020 July

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