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Alexander Mustill. Profile picture.

Alexander Mustill

Researcher

Alexander Mustill. Profile picture.

A low-eccentricity migration pathway for a 13-h-period Earth analogue in a four-planet system

Author

  • Luisa Maria Serrano
  • Davide Gandolfi
  • Alexander J. Mustill
  • Oscar Barragán
  • Judith Korth
  • Fei Dai
  • Seth Redfield
  • Malcolm Fridlund
  • Kristine W. F. Lam
  • Matías R. Díaz
  • Sascha Grziwa
  • Karen A. Collins
  • John H. Livingston
  • William D. Cochran
  • Coel Hellier
  • Salvatore E. Bellomo
  • Trifon Trifonov
  • European Southern Observatory Chile
  • Javier Alarcon
  • Jon M. Jenkins
  • David W. Latham
  • George Ricker
  • Sara Seager
  • Roland Vanderspeck
  • Joshua N. Winn
  • Simon Albrecht
  • Kevin I. Collins
  • Szilárd Csizmadia
  • Massachusetts Institute Technology
  • Hans J. Deeg
  • Massimiliano Esposito
  • Michael Fausnaugh
  • Iskra Georgieva
  • Elisa Goffo
  • Eike Guenther
  • Artie P. Hatzes
  • Steve B. Howell
  • Eric L. N. Jensen
  • Rafael Luque
  • Andrew W. Mann
  • Felipe Murgas
  • Hannah L. M. Osborne
  • Enric Palle
  • Carina M. Persson
  • Pam Rowden
  • Alexander Rudat
  • Alexis M. S. Smith
  • Joseph D. Twicken
  • Vincent Van Eylen
  • Carl Ziegler

Summary, in English

It is commonly accepted that exoplanets with orbital periods shorter than one day, also known as ultra-short-period (USP) planets, formed further out within their natal protoplanetary disks before migrating to their current-day orbits via dynamical interactions. One of the most accepted theories suggests a violent scenario involving high-eccentricity migration followed by tidal circularization. Here we present the discovery of a four-planet system orbiting the bright (V = 10.5) K6 dwarf star TOI-500. The innermost planet is a transiting, Earth-sized USP planet with an orbital period of ~13 hours, a mass of 1.42 ± 0.18 M⊕, a radius of $$1.16{6}_{-0.058}^{+0.061} \,R_{\oplus}$$and a mean density of $$4.8{9}_{-0.88}^{+1.03}\,{{{\rm{g}}}}\,{{{{\rm{cm}}}}}^{-3}$$. Via Doppler spectroscopy, we discovered that the system hosts 3 outer planets on nearly circular orbits with periods of 6.6, 26.2 and 61.3 days and minimum masses of 5.03 ± 0.41 M⊕, 33.12 ± 0.88 M⊕ and $$15.0{5}_{-1.11}^{+1.12}\,M_{\oplus}$$, respectively. The presence of both a USP planet and a low-mass object on a 6.6-day orbit indicates that the architecture of this system can be explained via a scenario in which the planets started on low-eccentricity orbits then moved inwards through a quasi-static secular migration. Our numerical simulations show that this migration channel can bring TOI-500 b to its current location in 2 Gyr, starting from an initial orbit of 0.02 au. TOI-500 is the first four-planet system known to host a USP Earth analogue whose current architecture can be explained via a non-violent migration scenario.

Department/s

  • Lund Observatory

Publishing year

2022

Language

English

Pages

736-750

Publication/Series

Nature Astronomy

Volume

6

Issue

6

Document type

Journal article

Publisher

Nature Publishing Group

Topic

  • Astronomy, Astrophysics and Cosmology

Status

Published

Project

  • Consolidating CHEOPS and preparing for PLATO: Exoplanet studies in the 2020s

ISBN/ISSN/Other

  • ISSN: 2397-3366