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: photometric

stars: individual: TYC 608-458-1

planetary systems

stars: abundances

techniques: radial velocities

Författare

E. W. Guenther

Thuringer Landessternwarte Tautenburg

Instituto Astrofisico de Canarias

O. Barragán

Universita degli Studi di Torino

F. Dai

Massachusetts Institute of Technology

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

Universitat Zurich

R. Helled

Universitat Zurich

J. Korth

Universitat zu Koln

J. Prieto-Arranz

Universidad de la Laguna

Instituto Astrofisico de Canarias

D. Nespral

Instituto Astrofisico de Canarias

Universidad de la Laguna

G. Antoniciello

Universita degli Studi di Torino

H. Deeg

Universidad de la Laguna

Instituto Astrofisico de Canarias

M. Hjorth

Aarhus Universitet

S. Grziwa

Universitat zu Koln

S. Albrecht

Aarhus Universitet

A. Hatzes

Thuringer Landessternwarte Tautenburg

H. Rauer

Technische Universitat Berlin

Deutsches Zentrum fur Luft- Und Raumfahrt

Sz. Csizmadia

Deutsches Zentrum fur Luft- Und Raumfahrt

A. M. S. Smith

Deutsches Zentrum fur Luft- Und Raumfahrt

J. Cabrera

Deutsches Zentrum fur Luft- Und Raumfahrt

N. Narita

National Institutes of Natural Sciences

National Institutes of Natural Sciences - National Astronomical Observatory of Japan

University of Tokyo

P. Arriagada

Carnegie Institution of Washington

J. Burt

Massachusetts Institute of Technology

R. P. Butler

Carnegie Institution of Washington

W. D. Cochran

University of Texas at Austin

J. D. Crane

Carnegie Observatories

Ph. Eigmüller

Deutsches Zentrum fur Luft- Und Raumfahrt

A. Erikson

Deutsches Zentrum fur Luft- Und Raumfahrt

J. A. Johnson

Harvard-Smithsonian Center for Astrophysics

A. Kiilerich

Aarhus Universitet

D. Kubyshkina

Institut fur Weltraumforschung

E. Palle

Universidad de la Laguna

Instituto Astrofisico de Canarias

Carina Persson

Astronomi och plasmafysik

M. Patzold

Universitat zu Koln

S. Sabotta

Thuringer 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

Leiden University

G. Nowak

Universidad de la Laguna

Instituto Astrofisico de Canarias

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- A93

Ämneskategorier

Astronomi, astrofysik och kosmologi

Fundament

Grundläggande vetenskaper

DOI

10.1051/0004-6361/201730885