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.

techniques: radial velocities

techniques: photometric

techniques: spectroscopic

stars: individual (K2-155 = EPIC 210897587)

planets and satellites: detection

Author

T. Hirano

Fei Dai

Massachusetts Institute of Technology (MIT)

Princeton University

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

Instituto Astrofisico de Canarias

University of La Laguna

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 Astrofisico 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 Astronomical Observatory of Japan

National Institutes of Natural Sciences

University of Tokyo

David Nespral

Instituto Astrofisico de Canarias

University of La Laguna

Prajwal Niraula

Wesleyan University

G. Nowak

Instituto Astrofisico de Canarias

University of La Laguna

Martin Pätzold

University of Cologne

Enric Palle

Instituto Astrofisico de Canarias

University of La Laguna

Carina Persson

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics, Galactic Astrophysics

H. Rauer

Technische Universität Berlin

German Aerospace Center (DLR)

I. Ribas

Institute of Space Sciences (ICE) - CSIC

Alexis M. S. Smith

German Aerospace Center (DLR)

V. Van Eylen

Leiden University

Astronomical Journal

0004-6256 (ISSN) 1538-3881 (eISSN)

Vol. 155 3 124

Exoplanets from space – CHEOPS and PLATO, ESA’s next two projects

Swedish National Space Board, 2017-01-01 -- 2022-12-31.

Subject Categories

Meteorology and Atmospheric Sciences

Astronomy, Astrophysics and Cosmology

Atom and Molecular Physics and Optics

DOI

10.3847/1538-3881/aaaa6e

More information

Latest update

9/10/2019