K2-106, a system containing a metal-rich planet and a planet of lower density
Artikel i vetenskaplig tidskrift, 2017
Planets in the mass range from 2 to 15 M_Earth are very diverse. Some of them have low densities, while others are very dense. By measuring the masses and radii, the mean densities, structure, and composition of the planets are constrained. These parameters also give us important information about their formation and evolution, and about possible processes for atmospheric loss.We determined the masses, radii, and mean densities for the two transiting planets orbiting K2-106. The inner planet has an ultra-short period of 0.57 days. The period of the outer planet is 13.3 days. Although the two planets have similar masses, their densities are very different. For K2-106b we derive Mb=8.36-0.94+0.96 M_Earh, Rb=1.52+/-0.16 R_Earth, and a high density of 13.1-3.6+5.4 g/cm^3. For K2-106c, we find Mc=5.8-3.0+3.3 M_Earth, Rc=2.50-0.26+0.27 R_Earth and a relatively low density of 2.0-1.1+1.6 g/cm^3.Since the system contains two planets of almost the same mass, but different distances from the host star, it is an excellent laboratory to study atmospheric escape. In agreement with the theory of atmospheric-loss processes, it is likely that the outer planet has a hydrogen-dominated atmosphere. The mass and radius of the inner planet is in agreement with theoretical models predicting an iron core containing 80+20-30% of its mass. Such a high metal content is surprising, particularly given that the star has an ordinary (solar) metal abundance. We discuss various possible formation scenarios for this unusual planet.
techniques: radial velocities
techniques: photometric
planetary systems
stars: abundances
stars: individual: TYC 608-458-1
Författare
E. W. Guenther
Thüringer Landessternwarte Tautenburg
Instituto Astrofisico de Canarias
O. Barragán
Universita degli Studi di Torino
F. Dai
Massachusetts Institute of Technology (MIT)
D. Gandolfi
Universita degli Studi di Torino
T. Hirano
Tokyo Institute of Technology
Malcolm Fridlund
Astronomi och plasmafysik
L. Fossati
Institut fur Weltraumforschung
A. Chau
Universität Zürich
R. Helled
Universität Zürich
J. Korth
Universität zu Köln
J. Prieto-Arranz
Universidad de la Laguna
Instituto Astrofisico de Canarias
D. Nespral
Universidad de la Laguna
Instituto Astrofisico de Canarias
G. Antoniciello
Universita degli Studi di Torino
H. Deeg
Universidad de la Laguna
Instituto Astrofisico de Canarias
M. Hjorth
Aarhus Universitet
S. Grziwa
Universität zu Köln
S. Albrecht
Aarhus Universitet
A. Hatzes
Thüringer Landessternwarte Tautenburg
H. Rauer
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
Technische Universität Berlin
Sz. Csizmadia
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
A. M. S. Smith
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
J. Cabrera
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
N. Narita
National Institutes of Natural Sciences
University of Tokyo
National Astronomical Observatory of Japan
P. Arriagada
Carnegie Institution of Washington
J. Burt
Massachusetts Institute of Technology (MIT)
R. P. Butler
Carnegie Institution of Washington
W. D. Cochran
The University of Texas at Austin
J. D. Crane
Carnegie Observatories
Ph. Eigmüller
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
A. Erikson
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
J. A. Johnson
Harvard-Smithsonian Center for Astrophysics
A. Kiilerich
Aarhus Universitet
D. Kubyshkina
Institut fur Weltraumforschung
E. Palle
Instituto Astrofisico de Canarias
Universidad de la Laguna
Carina Persson
Astronomi och plasmafysik
M. Patzold
Universität zu Köln
S. Sabotta
Thüringer Landessternwarte Tautenburg
B. Sato
Tokyo Institute of Technology
St. A. Shectman
Carnegie Observatories
J. K. Teske
Carnegie Observatories
Carnegie Institution of Washington
I. B. Thompson
Carnegie Observatories
V. Van Eylen
Universiteit Leiden
G. Nowak
Instituto Astrofisico de Canarias
Universidad de la Laguna
A. Vanderburg
Harvard-Smithsonian Center for Astrophysics
J. N. Winn
Princeton University
R. A. Wittenmyer
University of Southern Queensland
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 608 93- A93Exoplaneter från rymden - CHEOPS och PLATO
Rymdstyrelsen, 2017-01-01 -- 2022-12-31.
Ämneskategorier
Astronomi, astrofysik och kosmologi
Fundament
Grundläggande vetenskaper
DOI
10.1051/0004-6361/201730885