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

planets and satellites: detection

techniques: radial velocities

techniques: photometric

Author

D. Hidalgo

Instituto de Astrofísica de Canarias

University of La Laguna

E. Palle

University of La Laguna

Instituto de Astrofísica de Canarias

D. Gandolfi

University of Turin

Malcolm Fridlund

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics, Galactic Astrophysics

Leiden University

Grzegorz Nowak

University of La Laguna

R. Luque

Instituto Astrofisico de Canarias

University of La Laguna

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 Turin

University of Oxford

L Spina

Monash University

F. Rodler

European Southern Observatory Santiago

S. Albrecht

Aarhus University

D. Anderson

The University of Warwick

P. J. Amado

CSIC - Instituto de Astrofísica de Andalucía (IAA)

E. Bryant

CSIC - Instituto de Astrofísica de Andalucía (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 Astrofisico de Canarias

Ph. Eigmuller

German Aerospace Center (DLR)

Technische Universität Berlin

M. Endl

The University of Texas at Austin

A. Erikson

German Aerospace Center (DLR)

M. Esposito

Thüringer Landessternwarte Tautenburg

P. Figueira

European Southern Observatory Santiago

University of Porto

Iskra Georgieva

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics, Galactic Astrophysics

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

Astronomical Institute, Academy of Sciences of the Czech Republic v.v.i.

J. Korth

University of Cologne

M. Kuzuhara

National Institutes of Natural Sciences

M. Lafarga

Institute of Space Studies of Catalonia (IEEC)

Monash University

M. Lampon

CSIC - Instituto de Astrofísica de Andalucía (IAA)

I.C. Leão

Universidade Federal do Rio Grande do Sul (UFRGS)

J. Livingston

University of Tokyo

S. Mathur

University of La Laguna

Instituto Astrofisico de Canarias

Pilar Montanes Rodriguez

University of La Laguna

Instituto Astrofisico de Canarias

J. C. Morales

Institute of Space Sciences (ICE) - CSIC

Institute of Space Studies of Catalonia (IEEC)

F. Murgas

Instituto Astrofisico de Canarias

University of La Laguna

E. Nagel

Hamburg Observatory

N. Narita

Japan Science and Technology Agency

Instituto de Astrofísica de Canarias

National Institutes of Natural Sciences

L. D. Nielsen

University of Geneva

M. Patzold

University of Cologne

Carina Persson

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics, Galactic Astrophysics

J. Prieto-Arranz

Instituto Astrofisico de Canarias

University of La Laguna

A. Quirrenbach

Heidelberg University

H. Rauer

Technische Universität Berlin

German Aerospace Center (DLR)

Freie 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 A89

Exoplanets from space – CHEOPS and PLATO, ESA’s next two projects

Swedish National Space Board, 2017-01-01 -- 2022-12-31.

Subject Categories

Astronomy, Astrophysics and Cosmology

Roots

Basic sciences

DOI

10.1051/0004-6361/201937080

More information

Latest update

1/22/2021