Exoplanets around Low-mass Stars Unveiled by K2
Artikel i vetenskaplig tidskrift, 2018

We present the detection and follow-up observations of planetary candidates around low-mass stars observed by the K2 mission. Based on light-curve analysis, adaptive-optics imaging, and optical spectroscopy at low and high resolution (including radial velocity measurements), we validate 16 planets around 12 low-mass stars observed during K2 campaigns 5–10. Among the 16 planets, 12 are newly validated, with orbital periods ranging from 0.96 to 33 days. For one of the planets (K2-151b), we present ground-based transit photometry, allowing us to refine the ephemerides. Combining our K2 M-dwarf planets together with the validated or confirmed planets found previously, we investigate the dependence of planet radius R p on stellar insolation and metallicity [Fe/H]. We confirm that for periods P ≲ 2 days, planets with a radius Rp≳ 2 R⊕ are less common than planets with a radius between 1–2 R⊕. We also see a hint of the “radius valley” between 1.5 and 2 R⊕, which has been seen for close-in planets around FGK stars. These features in the radius/period distribution could be attributed to photoevaporation of planetary envelopes by high-energy photons from the host star, as they have for FGK stars. For the M dwarfs, though, the features are not as well defined, and we cannot rule out other explanations such as atmospheric loss from internal planetary heat sources or truncation of the protoplanetary disk. There also appears to be a relation between planet size and metallicity: the few planets larger than about 3 R⊕ are found around the most metal-rich M dwarfs.

techniques: spectroscopic

methods: observational

techniques: photometric

planets and satellites: detection

techniques: high angular resolution

techniques: radial velocities

Författare

Teruyuki Hirano

Tokyo Institute of Technology

Fei Dai

Princeton University

Massachusetts Institute of Technology (MIT)

D. Gandolfi

Universita degli Studi di Torino

Akihiko Fukui

National Astronomical Observatory of Japan

John H. Livingston

University of Tokyo

Kohei Miyakawa

Tokyo Institute of Technology

Michael Endl

The University of Texas at Austin

William D. Cochran

The University of Texas at Austin

Francisco J. Alonso-Floriano

Universidad Complutense de Madrid

Universiteit Leiden

M. Kuzuhara

National Astronomical Observatory of Japan

National Institutes of Natural Sciences

David Montes

Universidad Complutense de Madrid

Tsuguru Ryu

National Astronomical Observatory of Japan

The Graduate University for Advanced Studies (SOKENDAI)

Simon Albrecht

Aarhus Universitet

Oscar Barragan

Universita degli Studi di Torino

Juan Cabrera

Deutsches Zentrums für Luft- und Raumfahrt (DLR)

Szilard Csizmadia

Deutsches Zentrums für Luft- und Raumfahrt (DLR)

Hans Deeg

Instituto de Astrofísica de Canarias

Deutsches Zentrums für Luft- und Raumfahrt (DLR)

Philipp Eigmüller

Deutsches Zentrums für Luft- und Raumfahrt (DLR)

Anders Erikson

Deutsches Zentrums für Luft- und Raumfahrt (DLR)

Malcolm Fridlund

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

Universiteit Leiden

Sascha Grziwa

Universität zu Köln

Eike W. Guenther

Thüringer Landessternwarte Tautenburg

Artie P. Hatzes

Thüringer Landessternwarte Tautenburg

Judith Korth

Universität zu Köln

T. Kudo

National Astronomical Observatory of Japan

Nobuhiko Kusakabe

National Institutes of Natural Sciences

National Astronomical Observatory of Japan

Norio Narita

National Institutes of Natural Sciences

University of Tokyo

David Nespral

Instituto de Astrofísica de Canarias

Universidad de la Laguna

Grzegorz Nowak

Instituto de Astrofísica de Canarias

Universidad de la Laguna

Martin Pätzold

Universität zu Köln

Enric Palle

Universidad de la Laguna

Instituto de Astrofísica de Canarias

Carina Persson

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

Jorge Prieto-Arranz

Instituto de Astrofísica de Canarias

Universidad de la Laguna

Heike Rauer

Technische Universität Berlin

Deutsches Zentrums für Luft- und Raumfahrt (DLR)

I. Ribas

Institut d'Estudis Espacials de Catalunya (IEEC)

B. Sato

Tokyo Institute of Technology

Alexis M. S. Smith

Deutsches Zentrums für Luft- und Raumfahrt (DLR)

M. Tamura

University of Tokyo

National Institutes of Natural Sciences

National Astronomical Observatory of Japan

Yusuke Tanaka

University of Tokyo

Vincent Van Eylen

Universiteit Leiden

Joshua N. Winn

Princeton University

Astronomical Journal

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

Vol. 155 3 127-

Exoplaneter från rymden - CHEOPS och PLATO

Rymdstyrelsen, 2017-01-01 -- 2022-12-31.

Ämneskategorier

Astronomi, astrofysik och kosmologi

Fundament

Grundläggande vetenskaper

DOI

10.3847/1538-3881/aaa9c1

Mer information

Senast uppdaterat

2020-09-24