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Alexander Mustill. Profile picture.

Alexander Mustill

Researcher

Alexander Mustill. Profile picture.

The Kepler-11 system : Evolution of the stellar high-energy emission and initial planetary atmospheric mass fractions

Author

  • D. Kubyshkina
  • L. Fossati
  • A. J. Mustill
  • P. E. Cubillos
  • M. B. Davies
  • N. V. Erkaev
  • C. P. Johnstone
  • K. G. Kislyakova
  • H. Lammer
  • M. Lendl
  • P. Odert

Summary, in English

The atmospheres of close-in planets are strongly influenced by mass loss driven by the high-energy (X-ray and extreme ultraviolet, EUV) irradiation of the host star, particularly during the early stages of evolution. We recently developed a framework to exploit this connection and enable us to recover the past evolution of the stellar high-energy emission from the present-day properties of its planets, if the latter retain some remnants of their primordial hydrogen-dominated atmospheres. Furthermore, the framework can also provide constraints on planetary initial atmospheric mass fractions. The constraints on the output parameters improve when more planets can be simultaneously analysed. This makes the Kepler-11 system, which hosts six planets with bulk densities between 0.66 and 2.45 g cm-3, an ideal target. Our results indicate that the star has likely evolved as a slow rotator (slower than 85% of the stars with similar masses), corresponding to a high-energy emission at 150 Myr of between 1 and 10 times that of the current Sun. We also constrain the initial atmospheric mass fractions for the planets, obtaining a lower limit of 4.1% for planet c, a range of 3.7-5.3% for planet d, a range of 11.1-14% for planet e, a range of 1-15.6% for planet f, and a range of 4.7-8.7% for planet g assuming a disc dispersal time of 1 Myr. For planet b, the range remains poorly constrained. Our framework also suggests slightly higher masses for planets b, c, and f than have been suggested based on transit timing variation measurements. We coupled our results with published planet atmosphere accretion models to obtain a temperature (at 0.25 AU, the location of planet f) and dispersal time of the protoplanetary disc of 550 K and 1 Myr, although these results may be affected by inconsistencies in the adopted system parameters. This work shows that our framework is capable of constraining important properties of planet formation models.

Department/s

  • Lund Observatory

Publishing year

2019

Language

English

Publication/Series

Astronomy and Astrophysics

Volume

632

Document type

Journal article

Publisher

EDP Sciences

Topic

  • Astronomy, Astrophysics and Cosmology

Keywords

  • Hydrodynamics
  • Planets and satellites: atmospheres
  • Planets and satellites: individual: Kepler-11 system
  • Planets and satellites: physical evolution

Status

Published

Project

  • A unified picture of white dwarf planetary systems
  • What will the PLATO observatory tell us about star-planet tidal interactions?
  • IMPACT: Comets, asteroids and the habitability of planets

ISBN/ISSN/Other

  • ISSN: 0004-6361