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 language | English |
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Pages (from-to) | 5004-5021 |
Number of pages | 18 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 499 |
Issue number | 4 |
DOIs | |
Publication status | Published - 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