Greening of the brown-dwarf desert EPIC 212036875b: a 51 M-J object in a 5-day orbit around an F7V star
Artikel i vetenskaplig tidskrift, 2019
Context. Although more than 2000 brown dwarfs have been detected to date, mainly from direct imaging, their characterisation is difficult due to their faintness and model-dependent results. In the case of transiting brown dwarfs, however, it is possible to make direct high-precision observations. Aims. Our aim is to investigate the nature and formation of brown dwarfs by adding a new well-characterised object, in terms of its mass, radius and bulk density, to the currently small sample of less than 20 transiting brown dwarfs. Methods. One brown dwarf candidate was found by the KESPRINT consortium when searching for exoplanets in the K2 space mission Campaign 16 field. We combined the K2 photometric data with a series of multicolour photometric observations, imaging, and radial velocity measurements to rule out false positive scenarios and to determine the fundamental properties of the system. Results. We report the discovery and characterisation of a transiting brown dwarf in a 5.17-day eccentric orbit around the slightly evolved F7V star EPIC 212036875. We find a stellar mass of 1.15 +/- 0.08 M-circle dot, a stellar radius of 1.41 +/- 0.05 R-circle dot, and an age of 5.1 +/- 0.9 Gyr. The mass and radius of the companion brown dwarf are 51 +/- 2 M-J and 0.83 +/- 0.03 R-J, respectively, corresponding to a mean density of 108(-13)(+15) g cm(-3). Conclusions. EPIC 212036875 b is a rare object that resides in the brown-dwarf desert. In the mass-density diagram for planets, brown dwarfs, and stars, we find that all giant planets and brown dwarfs follow the same trend from similar to 0.3 M-J to the turn-over to hydrogen burning stars at similar to 73 M-J. EPIC 212036875 b falls close to the theoretical model for mature H/He dominated objects in this diagram as determined by interior structure models. We argue that EPIC 212036875 b formed via gravitational disc instabilities in the outer part of the disc, followed by a quick migration. Orbital tidal circularisation may have started early in its history for a brief period when the brown dwarf's radius was larger. The lack of spin-orbit synchronisation points to a weak stellar dissipation parameter (Q(star)' greater than or similar to 10(8)), which implies a circularisation timescale of greater than or similar to 23 Gyr, or suggests an interaction between the magnetic and tidal forces of the star and the brown dwarf.
stars: individual: EPIC 212036875
techniques: photometric
stars: fundamental parameters
planetary systems
techniques: radial velocities
Författare
Carina Persson
Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik
Szilard Csizmadia
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
Alexander J. Mustill
Lunds universitet
Malcolm Fridlund
Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik
Universiteit Leiden
Artie P. Hatzes
Thüringer Landessternwarte Tautenburg
Grzegorz Nowak
Universidad de la Laguna
Instituto de Astrofísica de Canarias
Iskra Georgieva
Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik
Davide Gandolfi
Universita degli Studi di Torino
Melvyn B. Davies
Lunds universitet
John H. Livingston
University of Tokyo
Enric Palle
Universidad de la Laguna
Instituto de Astrofísica de Canarias
Pilar Montanes Rodriguez
Universidad de la Laguna
Instituto de Astrofísica de Canarias
Michael Endl
The University of Texas at Austin
Teruyuki Hirano
Tokyo Institute of Technology
Jorge Prieto-Arranz
Instituto de Astrofísica de Canarias
Universidad de la Laguna
Judith Korth
Universität zu Köln
Sascha Grziwa
Universität zu Köln
Massimiliano Esposito
Thüringer Landessternwarte Tautenburg
Simon Albrecht
Aarhus Universitet
Marshall C. Johnson
Ohio State University
Oscar Barragan
Universita degli Studi di Torino
University of Oxford
Hannu Parviainen
Instituto de Astrofísica de Canarias
Universidad de la Laguna
Vincent Van Eylen
Princeton University
Roi Alonso Sobrino
Instituto de Astrofísica de Canarias
Universidad de la Laguna
Paul G. Beck
Karl-Franzens-Universität Graz
Universidad de la Laguna
Instituto de Astrofísica de Canarias
Juan Cabrera
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
Ilaria Carleo
Wesleyan University
William D. Cochran
The University of Texas at Austin
Fei Dai
Massachusetts Institute of Technology (MIT)
Princeton University
Hans J. Deeg
Instituto de Astrofísica de Canarias
Universidad de la Laguna
Jerome P. de Leon
University of Tokyo
Philipp Eigmueller
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
Anders Erikson
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
Akai Fukui
National Institutes of Natural Sciences
Lucia Gonzalez-Cuesta
Universidad de la Laguna
Instituto de Astrofísica de Canarias
Eike W. Guenther
Thüringer Landessternwarte Tautenburg
Diego Hidalgo
Instituto de Astrofísica de Canarias
Universidad de la Laguna
Maria Hjorth
Aarhus Universitet
Petr Kabath
Czech Academy of Sciences
Emil Knudstrup
Aarhus Universitet
Nobuhiko Kusakabe
National Institutes of Natural Sciences
Kristine W. F. Lam
Technische Universität Berlin
Mikkel N. Lund
Aarhus Universitet
Rafael Luque
Universidad de la Laguna
Instituto de Astrofísica de Canarias
Savita Mathur
Universidad de la Laguna
Instituto de Astrofísica de Canarias
Felipe Murgas
Universidad de la Laguna
Instituto de Astrofísica de Canarias
Norio Narita
National Institutes of Natural Sciences
Japan Science and Technology Agency
Instituto de Astrofísica de Canarias
University of Tokyo
David Nespral
Instituto de Astrofísica de Canarias
Universidad de la Laguna
Prajwal Niraula
Massachusetts Institute of Technology (MIT)
Henrik Olofsson
Chalmers, Rymd-, geo- och miljövetenskap, Onsala rymdobservatorium
Martin Paetzold
Universität zu Köln
Heike Rauer
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
Technische Universität Berlin
Seth Redfield
Wesleyan University
Ignasi Ribas
Institut d'Estudis Espacials de Catalunya (IEEC)
Consejo Superior de Investigaciones Científicas (CSIC)
Marek Skarka
Czech Academy of Sciences
Masarykova Univerzita
Alexis M. S. Smith
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
Jan Subjak
Czech Academy of Sciences
Univerzita Karlova
Motohide Tamura
University of Tokyo
National Institutes of Natural Sciences
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 628 A64Exoplaneter från rymden - CHEOPS och PLATO, ESA's nästa två missioner
Rymdstyrelsen (174/18), 2017-01-01 -- 2022-12-31.
Ämneskategorier
Astronomi, astrofysik och kosmologi
Annan fysik
Den kondenserade materiens fysik
Fundament
Grundläggande vetenskaper
Infrastruktur
Onsala rymdobservatorium
DOI
10.1051/0004-6361/201935505