K2-111: An old system with two planets in near-resonance

A. Mortier*, M. R. Zapatero Osorio, L. Malavolta, Y. Alibert, K. Rice, J. Lillo-Box, A. Vanderburg, M. Oshagh, L. Buchhave, V. Adibekyan, E. Delgado Mena, M. Lopez-Morales, D. Charbonneau, S. G. Sousa, C. Lovis, L. Affer, C. Allende Prieto, S. C.C. Barros, S. Benatti, A. S. BonomoW. Boschin, F. Bouchy, A. Cabral, A. Collier Cameron, R. Cosentino, S. Cristiani, O. D.S. Demangeon, P. Di Marcantonio, V. D'Odorico, X. Dumusque, D. Ehrenreich, P. Figueira, A. Fiorenzano, A. Ghedina, J. I. González Hernández, J. Haldemann, A. Harutyunyan, R. D. Haywood, D. W. Latham, B. Lavie, G. Lo Curto, J. Maldonado, A. Manescau, C. J.A.P. Martins, M. Mayor, D. Mégevand, A. Mehner, G. Micela, P. Molaro, E. Molinari, N. J. Nunes, F. A. Pepe, E. Palle, D. Phillips, G. Piotto, M. Pinamonti, E. Poretti, M. Riva, R. Rebolo, N. C. Santos, D. Sasselov, A. Sozzetti, A. Suárez Mascareño, S. Udry, R. G. West, C. A. Watson, T. G. Wilson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

This paper reports on the detailed characterization of the K2-111 planetary system with K2, WASP, and ASAS-SN photometry, as well as high-resolution spectroscopic data from HARPS-N and ESPRESSO. The host, K2-111, is confirmed to be a mildly evolved (log g = 4.17), iron-poor ([Fe/H] = -0.46), but alpha-enhanced ([α/Fe]=0.27), chromospherically quiet, very old thick disc G2 star. A global fit, performed by using PyORBIT, shows that the transiting planet, K2-111 b, orbits with a period Pb = 5.3518 ± 0.0004 d and has a planet radius of 1.82+0.11-0.09 R⊙ and a mass of 5.29+0.76-0.77 M⊙, resulting in a bulk density slightly lower than that of the Earth. The stellar chemical composition and the planet properties are consistent with K2-111 b being a terrestrial planet with an iron core mass fraction lower than the Earth. We announce the existence of a second signal in the radial velocity data that we attribute to a non-transiting planet, K2-111 c, with an orbital period of 15.6785 ± 0.0064 d, orbiting in near-3:1 mean motion resonance with the transiting planet, and a minimum planet mass of 11.3 ± 1.1 M⊙. Both planet signals are independently detected in the HARPS-N and ESPRESSO data when fitted separately. There are potentially more planets in this resonant system, but more well-sampled data are required to confirm their presence and physical parameters.

Original languageEnglish
Pages (from-to)5004-5021
Number of pages18
JournalMonthly Notices of the Royal Astronomical Society
Volume499
Issue number4
DOIs
Publication statusPublished - 1 Dec 2020

Bibliographical note

Publisher Copyright:
© 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.

Keywords

  • planets and satellites: detection
  • stars: individual (K2-111)
  • techniques: photometric
  • techniques: radial velocities
  • techniques: spectroscopic

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Fingerprint

Dive into the research topics of 'K2-111: An old system with two planets in near-resonance'. Together they form a unique fingerprint.

Cite this