Three planets transiting the evolved star EPIC 249893012: a hot 8.8-Mearth super-Earth and two warm 14.7 and 10.2-Mearth sub-Neptunes
Journal article, 2020
We report the discovery of a new planetary system with three transiting planets, one super-Earth and two sub-Neptunes, that orbit EPIC 249893012, a G8 IV-V evolved star (M⋆ = 1.05 ± 0.05 M☉, R⋆ = 1.71 ± 0.04 R☉, Teff = 5430 ± 85 K). The star is just leaving the main sequence. We combined K2 photometry with IRCS adaptive-optics imaging and HARPS, HARPS-N, and CARMENES high-precision radial velocity measurements to confirm the planetary system, determine the stellar parameters, and measure radii, masses, and densities of the three planets. With an orbital period of 3.5949-0.0007+0.0007days, a mass of 8.75-1.08+1.09 M⊕, and a radius of 1.95-0.08+0.09 R⊕, the inner planet b is compatible with nickel-iron core and a silicate mantle (ρb = 6.39-1.04+1.19 g cm-3). Planets c and d with orbital periods of 15.624-0.001+0.001 and 35.747-0.005+0.005 days, respectively, have masses and radii of 14.67-1.89+1,84 M⊕ and 3.67-0.14+0.17 R⊕ and 10.18-2.42+2.46 M⊕ and 3.94-0.12+0.13 R⊕, respectively, yielding a mean density of 1.62-0.29+0.30 and 0.91-0.23+0.25 g cm-3, respectively. The radius of planet b lies in the transition region between rocky and gaseous planets, but its density is consistent with a rocky composition. Its semimajor axis and the corresponding photoevaporation levels to which the planet has been exposed might explain its measured density today. In contrast, the densities and semimajor axes of planets c and d suggest a very thick atmosphere. The singularity of this system, which orbits a slightly evolved star that is just leaving the main sequence, makes it a good candidate for a deeper study from a dynamical point of view.
planets and satellites: fundamental parameters
planetary systems
techniques: radial velocities
planets and satellites: detection
techniques: photometric
Author
D. Hidalgo
University of La Laguna
Instituto de Astrofísica de Canarias
E. Palle
Instituto de Astrofísica de Canarias
University of La Laguna
D. Gandolfi
University of Turin
Malcolm Fridlund
Leiden University
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Grzegorz Nowak
University of La Laguna
R. Luque
University of La Laguna
Instituto de Astrofísica de Canarias
T. Hirano
Tokyo Institute of Technology
A. B. Justesen
National Astronomical Observatory of Japan
W. D. Cochran
The University of Texas at Austin
O. Barragan
University of Oxford
University of Turin
L Spina
Monash University
F. Rodler
European Southern Observatory Santiago
S. Albrecht
Aarhus University
D. Anderson
The University of Warwick
P. J. Amado
Institute of Astrophysics of Andalusia (IAA)
E. Bryant
Institute of Astrophysics of Andalusia (IAA)
The University of Warwick
J. A. Caballero
Spanish Astrobiology Center (INTA-CSIC)
Juan Cabrera
German Aerospace Center (DLR)
Szilard Csizmadia
German Aerospace Center (DLR)
F. Dai
Princeton University
Massachusetts Institute of Technology (MIT)
J. de Leon
National Institutes of Natural Sciences
Hans Deeg
University of La Laguna
Instituto de Astrofísica de Canarias
Ph. Eigmuller
Technische Universität Berlin
German Aerospace Center (DLR)
M. Endl
The University of Texas at Austin
A. Erikson
German Aerospace Center (DLR)
M. Esposito
Thüringer Landessternwarte Tautenburg
P. Figueira
University of Porto
European Southern Observatory Santiago
Iskra Georgieva
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
S. Grziwa
University of Cologne
E. Guenther
Thüringer Landessternwarte Tautenburg
Artie P. Hatzes
Thüringer Landessternwarte Tautenburg
M. Hjorth
Aarhus University
H. J. Hoeijmakers
University of Geneva
University of Bern
P. Kabath
Czech Academy of Sciences
J. Korth
University of Cologne
M. Kuzuhara
National Institutes of Natural Sciences
M. Lafarga
Monash University
Institute of Space Studies of Catalonia (IEEC)
M. Lampon
Institute of Astrophysics of Andalusia (IAA)
I.C. Leão
Universidade Federal do Rio Grande do Sul (UFRGS)
J. Livingston
University of Tokyo
S. Mathur
University of La Laguna
Instituto de Astrofísica de Canarias
Pilar Montanes Rodriguez
Instituto de Astrofísica de Canarias
University of La Laguna
J. C. Morales
Institute of Space Studies of Catalonia (IEEC)
Institute of Space Sciences (ICE) - CSIC
F. Murgas
University of La Laguna
Instituto de Astrofísica de Canarias
E. Nagel
Hamburg Observatory
N. Narita
National Institutes of Natural Sciences
Japan Science and Technology Agency
Instituto de Astrofísica de Canarias
L. D. Nielsen
University of Geneva
M. Patzold
University of Cologne
Carina Persson
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
J. Prieto-Arranz
Instituto de Astrofísica de Canarias
University of La Laguna
A. Quirrenbach
Heidelberg University
H. Rauer
Freie Universität Berlin
German Aerospace Center (DLR)
Technische Universität Berlin
S. Redfield
Wesleyan University
A. Reiners
University of Göttingen
I Ribas
Institute of Space Sciences (ICE) - CSIC
Institute of Space Studies of Catalonia (IEEC)
A. Smith
German Aerospace Center (DLR)
J. Subjak
Charles University
Czech Academy of Sciences
V. Van Eylen
University College London (UCL)
P. A. Wilson
The University of Warwick
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 636 A89Exoplanets from space – CHEOPS and PLATO, ESA’s next two projects
Swedish National Space Board (174/18), 2017-01-01 -- 2022-12-31.
Subject Categories
Astronomy, Astrophysics and Cosmology
Roots
Basic sciences
DOI
10.1051/0004-6361/201937080