K2-280 b - a low density warm sub-Saturn around a mildly evolved star
Journal article, 2020
We present an independent discovery and detailed characterization of K2-280 b, a transiting low density warm sub-Saturn in a 19.9-d moderately eccentric orbit (e = 0.35(-0.04)(+0.05)) from K2 campaign 7. A joint analysis of high precision HARPS, HARPS-N, and FIES radial velocity measurements and K2 photometric data indicates that K2-280 b has a radius of R-b = 7.50 +/- 0.44 R-circle plus and a mass of M-b = 37.1 +/- 5.6 M-circle plus, yielding a mean density of rho(b) = 0.48(-0.10)(+0.13) g cm(-3). The host star is a mildly evolved G7 star with an effective temperature of T-eff = 5500 +/- 100 K, a surface gravity of log g(star) = 4.21 +/- 0.05 (cgs), and an iron abundance of [Fe/H] = 0.33 +/- 0.08 dex, and with an inferred mass of M-star = 1.03 +/- 0.03 M-circle dot and a radius of R-star = 1.28 +/- 0.07 R-circle dot. We discuss the importance of K2-280 b for testing formation scenarios of sub-Saturn planets and the current sample of this intriguing group of planets that are absent in the Solar system.
techniques: spectroscopic
techniques: photometric
techniques: radial velocities
stars: individual: (EPIC 216494238, K2-280)
planets and satellites: detection
Author
Grzegorz Nowak
University of La Laguna
Instituto de Astrofísica de Canarias
Enric Palle
University of La Laguna
Instituto de Astrofísica de Canarias
Davide Gandolfi
University of Turin
Hans J. Deeg
University of La Laguna
Instituto de Astrofísica de Canarias
Teruyuki Hirano
Tokyo Institute of Technology
Oscar Barragan
University of Turin
University of Oxford
Masayuki Kuzuhara
National Institutes of Natural Sciences
Fei Dai
Massachusetts Institute of Technology (MIT)
Princeton University
Rafael Luque
Instituto de Astrofísica de Canarias
University of La Laguna
Carina Persson
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Malcolm Fridlund
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Marshall C. Johnson
Las Cumbres Observatory Global Telescope Network
Judith Korth
University of Cologne
John H. Livingston
University of Tokyo
Sascha Grziwa
University of Cologne
Savita Mathur
Instituto de Astrofísica de Canarias
University of La Laguna
Artie P. Hatzes
Thüringer Landessternwarte Tautenburg
Jorge Prieto-Arranz
Instituto de Astrofísica de Canarias
University of La Laguna
David Nespral
University of La Laguna
Instituto de Astrofísica de Canarias
Diego Hidalgo
Instituto de Astrofísica de Canarias
University of La Laguna
Maria Hjorth
Aarhus University
Simon Albrecht
Aarhus University
Vincent Van Eylen
Princeton University
Kristine W. F. Lam
Technische Universität Berlin
William D. Cochran
The University of Texas at Austin
Massimiliano Esposito
Thüringer Landessternwarte Tautenburg
Szilard Csizmadia
German Aerospace Center (DLR)
Eike W. Guenther
Thüringer Landessternwarte Tautenburg
Petr Kabath
Czech Academy of Sciences
Pere Blay
Valencian International University
Rafael Brahm
Adolfo Ibáñez University
Millennium Institute of Astrophysics
Andres Jordan
Adolfo Ibáñez University
Millennium Institute of Astrophysics
Nestor Espinoza
Max Planck Society
Felipe Rojas
Pontificia Universidad Catolica de Chile
Millennium Institute of Astrophysics
Nuria Casasayas Barris
Instituto de Astrofísica de Canarias
University of La Laguna
Florian Rodler
European Southern Observatory Santiago
Roi Alonso Sobrino
Instituto de Astrofísica de Canarias
University of La Laguna
J. Cabrera
German Aerospace Center (DLR)
Ilaria Carleo
Wesleyan University
Alexander Chaushev
Technische Universität Berlin
Jerome de Leon
University of Tokyo
Philipp Eigmueller
German Aerospace Center (DLR)
Michael Endl
The University of Texas at Austin
Anders Erikson
German Aerospace Center (DLR)
Akihiko Fukui
National Institutes of Natural Sciences
Iskra Georgieva
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Lucia Gonzalez-Cuesta
University of La Laguna
Instituto de Astrofísica de Canarias
Emil Knudstrup
Aarhus University
Mikkel N. Lund
Aarhus University
Pilar Montanes Rodriguez
Instituto de Astrofísica de Canarias
University of La Laguna
Felipe Murgas
Instituto de Astrofísica de Canarias
University of La Laguna
Norio Narita
Japan Science and Technology Agency
Instituto de Astrofísica de Canarias
National Institutes of Natural Sciences
Prajwal Niraula
Massachusetts Institute of Technology (MIT)
Martin Paetzold
University of Cologne
Heike Rauer
German Aerospace Center (DLR)
Technische Universität Berlin
Seth Redfield
Wesleyan University
Ignasi Ribas
Spanish National Research Council (CSIC)
Institute of Space Studies of Catalonia (IEEC)
Marek Skarka
Masaryk University
Czech Academy of Sciences
Alexis M. S. Smith
German Aerospace Center (DLR)
Jano Subjak
Czech Academy of Sciences
Charles University
Monthly Notices of the Royal Astronomical Society
0035-8711 (ISSN) 1365-2966 (eISSN)
Vol. 497 4 4423-4435Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
Other Earth and Related Environmental Sciences
Materials Chemistry
DOI
10.1093/mnras/staa2077