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, Galaktisk astrofysik

Szilard Csizmadia

Deutsches Zentrums für Luft- und Raumfahrt (DLR)

Alexander J. Mustill

Lunds universitet

Malcolm Fridlund

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik, Galaktisk astrofysik

Universiteit Leiden

Artie P. Hatzes

Thüringer Landessternwarte Tautenburg

Grzegorz Nowak

Universidad de la Laguna

Instituto Astrofisico de Canarias

Iskra Georgieva

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik, Galaktisk astrofysik

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 Astrofisico de Canarias

Pilar Montanes Rodriguez

Universidad de la Laguna

Instituto Astrofisico de Canarias

Michael Endl

The University of Texas at Austin

Teruyuki Hirano

Tokyo Institute of Technology

Jorge Prieto-Arranz

Instituto Astrofisico 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 Astrofisico de Canarias

Universidad de la Laguna

Vincent Van Eylen

Princeton University

Roi Alonso Sobrino

Instituto Astrofisico de Canarias

Universidad de la Laguna

Paul G. Beck

Karl-Franzens-Universität Graz

Universidad de la Laguna

Instituto Astrofisico 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 Astrofisico 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 Astrofisico de Canarias

Eike W. Guenther

Thüringer Landessternwarte Tautenburg

Diego Hidalgo

Instituto Astrofisico 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 Astrofisico de Canarias

Savita Mathur

Universidad de la Laguna

Instituto Astrofisico de Canarias

Felipe Murgas

Universidad de la Laguna

Instituto Astrofisico de Canarias

Norio Narita

National Institutes of Natural Sciences

Japan Science and Technology Agency

Instituto Astrofisico de Canarias

University of Tokyo

David Nespral

Instituto Astrofisico de Canarias

Universidad de la Laguna

Prajwal Niraula

Massachusetts Institute of Technology (MIT)

Henrik Olofsson

Chalmers, Rymd-, geo- och miljövetenskap, Onsala rymdobservatorium, Observationssupport

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 v Praze

Motohide Tamura

University of Tokyo

National Institutes of Natural Sciences

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 628 A64

Exoplaneter från rymden - CHEOPS och PLATO

Rymdstyrelsen, 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

Mer information

Senast uppdaterat

2020-09-23