K2-265 b: a transiting rocky super-Earth

K. W. F. Lam (1) , A. Santerne (2) , S. G. Sousa (3) , A. Vigan (2) , D. J. Armstrong (2) , S. C. C. Barros (2) , B. Brugger (2) , V. Adibekyan (4) , J. -M. Almenara (5) , E. Delgado Mena (3) , X. Dumusque (6) , D. Barrado (7) , D. Bayliss (2) , A. S. Bonomo (8) , F. Bouchy (2) , D. J. A. Brown (2) , D. Ciardi (9) , M. Deleuil (2) , O. Demangeon (10) , F. Faedi (11) , E. Foxell (2) , J. A. G. Jackman (2) , G. W. King (2) , J. Kirk (12) , R. Ligi (2) , J. Lillo-Box (13) , Téodolina Lopez (2) , C. Lovis (6) , T. Louden (1) , L. D. Nielsen (6) , J. Mccormac (1) , O. Mousis (2) , H. P. Osborn (2) , D. Pollacco (1) , N. C. Santos (4) , S. Udry (6) , P. J. Wheatley (1)

1 University of Warwick [Coventry]
2 LAM - Laboratoire d'Astrophysique de Marseille
3 Universidade do Porto = University of Porto
4 CAUP - Centro de Astrofísica da Universidade do Porto
5 IAC - Instituto de Astrofisica de Canarias
6 ObsGE - Observatoire Astronomique de l'Université de Genève
7 Departamento de Astrofisica [Madrid]
8 OATo - INAF - Osservatorio Astrofisico di Torino
9 Caltech Department of Astronomy [Pasadena]
10 UP11 - Université Paris-Sud - Paris 11
11 OACT - INAF - Osservatorio Astrofisico di Catania
12 School of Physics and Astronomy [Cardiff]
13 ESO - European Southern Observatory

We report the discovery of the super-Earth K2-265 b detected with K2 photometry. The planet orbits a bright (V_mag = 11.1) star of spectral type G8V with a period of 2.37 days. We obtained high-precision follow-up radial velocity measurements from HARPS, and the joint Bayesian analysis showed that K2-265 b has a radius of 1.71 +/- 0.11 R_earth and a mass of 6.54 +/- 0.84 M_earth, corresponding to a bulk density of 7.1 +/- 1.8 g/cm^3 . Composition analysis of the planet reveals an Earth-like, rocky interior, with a rock mass fraction of 80%. The short orbital period and small radius of the planet puts it below the lower limit of the photoevaporation gap, where the envelope of the planet could have eroded due to strong stellar irradiation, leaving behind an exposed core. Knowledge of the planet core composition allows us to infer the possible formation and evolution mechanism responsible for its current physical parameters.

Domaines: Planète et Univers [physics]; Astrophysique [astro-ph]

K. W. F. Lam, A. Santerne, S. G. Sousa, A. Vigan, D. J. Armstrong, et al.. K2-265 b: a transiting rocky super-Earth. Astronomy and Astrophysics - A&A, 2018, 620, pp.A77. ⟨10.1051/0004-6361/201834073⟩. ⟨hal-02076156⟩