K2-155: A Bright Metal-poor M Dwarf with Three Transiting Super-Earths
Journal article, 2018
We report on the discovery of three transiting super-Earths around K2-155 (EPIC 210897587), a relatively bright early M dwarf (V = 12.81 mag) observed during Campaign 13 of the NASA K2 mission. To characterize the system and validate the planet candidates, we conducted speckle imaging and high-dispersion optical spectroscopy, including radial velocity measurements. Based on the K2 light curve and the spectroscopic characterization of the host star, the planet sizes and orbital periods are 1.55 -0.17 +0.20 R ⊕ and 6.34365 ±0.00028 days for the inner planet; 1.95 -0.22 +0.27 R ⊕ and 13.85402 ±0.00088 days for the middle planet; and 1.64 -0.17 +0.18 R ⊕ and 40.6835 ±0.0031 days for the outer planet. The outer planet (K2-155d) is near the habitable zone, with an insolation 1.67 ±0.38 times that of the Earth. The planet's radius falls within the range between that of smaller rocky planets and larger gas-rich planets. To assess the habitability of this planet, we present a series of three-dimensional global climate simulations, assuming that K2-155d is tidally locked and has an Earth-like composition and atmosphere. We find that the planet can maintain a moderate surface temperature if the insolation proves to be smaller than ∼1.5 times that of the Earth. Doppler mass measurements, transit spectroscopy, and other follow-up observations should be rewarding, as K2-155 is one of the optically brightest M dwarfs known to harbor transiting planets.
stars: individual (K2-155 = EPIC 210897587)
techniques: radial velocities
planets and satellites: detection
techniques: photometric
techniques: spectroscopic
Author
T. Hirano
Fei Dai
Princeton University
Massachusetts Institute of Technology (MIT)
J.H. Livingston
University of Tokyo
Yuka Fujii
Tokyo Institute of Technology
William D. Cochran
The University of Texas at Austin
M. Endl
The University of Texas at Austin
D. Gandolfi
University of Turin
S. Redfield
Wesleyan University
N. Joshua
Princeton University
E. W. Guenther
Thüringer Landessternwarte Tautenburg
J. Prieto-Arranz
University of La Laguna
Instituto de Astrofísica de Canarias
Simon Albrecht
Aarhus University
O. Barragán
University of Turin
J. Cabrera
German Aerospace Center (DLR)
P.W. Cauley
Arizona State University
Szilard Csizmadia
German Aerospace Center (DLR)
H. Deeg
Instituto de Astrofísica de Canarias
University of La Laguna
P. Eigmüller
German Aerospace Center (DLR)
Anders Erikson
German Aerospace Center (DLR)
Malcolm Fridlund
Leiden University
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
A. Fukui
National Astronomical Observatory of Japan
S. Grziwa
University of Cologne
A. Hatzes
Thüringer Landessternwarte Tautenburg
Judith Korth
University of Cologne
Norio Narita
National Institutes of Natural Sciences
University of Tokyo
National Astronomical Observatory of Japan
David Nespral
Instituto de Astrofísica de Canarias
University of La Laguna
Prajwal Niraula
Wesleyan University
G. Nowak
University of La Laguna
Instituto de Astrofísica de Canarias
Martin Pätzold
University of Cologne
Enric Palle
University of La Laguna
Instituto de Astrofísica de Canarias
Carina Persson
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
H. Rauer
Technische Universität Berlin
German Aerospace Center (DLR)
I. Ribas
Spanish National Research Council (CSIC)
Alexis M. S. Smith
German Aerospace Center (DLR)
V. Van Eylen
Leiden University
Astronomical Journal
0004-6256 (ISSN) 1538-3881 (eISSN)
Vol. 155 3 124Exoplanets from space – CHEOPS and PLATO, ESA’s next two projects
Swedish National Space Board (174/18), 2017-01-01 -- 2022-12-31.
Subject Categories (SSIF 2011)
Meteorology and Atmospheric Sciences
Astronomy, Astrophysics and Cosmology
Atom and Molecular Physics and Optics
DOI
10.3847/1538-3881/aaaa6e