Mass determination of the 1:3:5 near-resonant planets transiting GJ 9827 (K2-135)
Artikel i vetenskaplig tidskrift, 2018
Context. Multiplanet systems are excellent laboratories to test planet formation models as all planets are formed under the same initial conditions. In this context, systems transiting bright stars can play a key role, since planetary masses, radii, and bulk densities can be measured. Aims. GJ 9827 (K2-135) has recently been found to host a tightly packed system consisting of three transiting small planets whose orbital periods of 1.2, 3.6, and 6.2 days are near the 1:3:5 ratio. GJ 9827 hosts the nearest planetary system (~30 pc) detected by NASA's Kepler or K2 space mission. Its brightness (V = 10.35 mag) makes the star an ideal target for detailed studies of the properties of its planets. Methods. Combining the K2 photometry with high-precision radial-velocity measurements gathered with the FIES, HARPS, and HARPS-N spectrographs we revised the system parameters and derive the masses of the three planets. Results. We find that GJ 9827 b has a mass of Mb = 3.69-0.46+0.48 M and a radius of Rb = 1.58-0.13+0.14 R, yielding a mean density of ρb = 5.11-1.27+1.74 g cm-3. GJ 9827 c has a mass of Mc = 1.45-0.57+0.58 M, radius of Rc = 1.24-0.11+0.11 R, and a mean density of ρc = 4.13-1.77+2.31 g cm-3. For GJ 9827 d, we derive Md = 1.45-0.57+0.58 M, Rd = 1.24-0.11+0.11 R, and ρd = 1.51-0.53+0.71 g cm-3. Conclusions. GJ 9827 is one of the few known transiting planetary systems for which the masses of all planets have been determined with a precision better than 30%. This system is particularly interesting because all three planets are close to the limit between super-Earths and sub-Neptunes. The planetary bulk compositions are compatible with a scenario where all three planets formed with similar core and atmosphere compositions, and we speculate that while GJ 9827 b and GJ 9827 c lost their atmospheric envelopes, GJ 9827 d maintained its primordial atmosphere, owing to the much lower stellarirradiation. This makes GJ 9827 one of the very few systems where the dynamical evolution and the atmosphericescape can be studied in detail for all planets, helping us to understand how compact systems form and evolve.
Stars: abundances
Stars: individual: GJ 9827
Techniques: radial velocities
Planetary systems
Techniques: high angular resolution
Techniques: photometric
Författare
J. Prieto-Arranz
Instituto de Astrofísica de Canarias
Universidad de la Laguna
E. Palle
Universidad de la Laguna
Instituto de Astrofísica de Canarias
D. Gandolfi
Universita degli Studi di Torino
O. Barragán
Universita degli Studi di Torino
E. W. Guenther
Instituto de Astrofísica de Canarias
Thüringer Landessternwarte Tautenburg
Fei Dai
Massachusetts Institute of Technology (MIT)
Princeton University
Malcolm Fridlund
Chalmers, Rymd-, geo- och miljövetenskap, Onsala rymdobservatorium
Universiteit Leiden
T. Hirano
Tokyo Institute of Technology
J. Livingston
University of Tokyo
R. Luque
Instituto de Astrofísica de Canarias
Universidad de la Laguna
Prajwal Niraula
Wesleyan University
Carina Persson
Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik
S. Redfield
Wesleyan University
Simon Albrecht
Aarhus Universitet
R. Alonso
Instituto de Astrofísica de Canarias
Universidad de la Laguna
Giuliano Antoniciello
Universita degli Studi di Torino
J. Cabrera
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
William D. Cochran
The University of Texas at Austin
Szilard Csizmadia
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
H. Deeg
Universidad de la Laguna
Instituto de Astrofísica de Canarias
P. Eigmüller
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
M. Endl
The University of Texas at Austin
Anders Erikson
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
M.E. Everett
National Optical Astronomy Observatory
A. Fukui
National Astronomical Observatory of Japan
S. Grziwa
Universität zu Köln
A. Hatzes
Thüringer Landessternwarte Tautenburg
D. Hidalgo
Instituto de Astrofísica de Canarias
Universidad de la Laguna
M. Hjorth
Aarhus Universitet
Judith Korth
Universität zu Köln
D. Lorenzo-Oliveira
Universidade Cidade de Sao Paulo
F. Murgas
Aarhus Universitet
Norio Narita
University of Tokyo
National Institutes of Natural Sciences
David Nespral
Universidad de la Laguna
Instituto de Astrofísica de Canarias
G. Nowak
Instituto de Astrofísica de Canarias
Universidad de la Laguna
Martin Pätzold
Universität zu Köln
P. Montañez Rodríguez
Instituto de Astrofísica de Canarias
Universidad de la Laguna
H. Rauer
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
Technische Universität Berlin
I. Ribas
Institut de Ciències de l'Espai (ICE) - CSIC
Institut d'Estudis Espacials de Catalunya (IEEC)
Alexis M. S. Smith
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
T. Trifonov
Max-Planck-Gesellschaft
Vincent Van Eylen
Universiteit Leiden
J. N. Winn
Princeton University
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 618 32872Exoplaneter från rymden - CHEOPS och PLATO, ESA's nästa två missioner
Rymdstyrelsen (174/18), 2017-01-01 -- 2022-12-31.
Ämneskategorier
Astronomi, astrofysik och kosmologi
Fundament
Grundläggande vetenskaper
DOI
10.1051/0004-6361/201832872