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Mikkel Nørup Lund

Signatures of Magnetic Activity in the Seismic Data of Solar-type Stars Observed by Kepler

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  • A. R.G. Santos, Space Science Institute, CAUP, Universidade do Porto, Birmingham University
  • ,
  • T. L. Campante, Instituto de Astrofisica e Ciencias Do Espaco, CAUP, Departamento de Física e Astronomia, Universidade do Porto, School of Physics and Astronomy, University of Birmingham, UK, Birmingham University
  • ,
  • W. J. Chaplin, School of Physics and Astronomy, University of Birmingham, UK
  • ,
  • M. S. Cunha, CAUP, Universidade do Porto
  • ,
  • M. N. Lund
  • R. Kiefer, Kiepenheuer-Institut für Sonnenphysik
  • ,
  • D. Salabert, Université Paris-Saclay, Université Paris—Denis Diderot
  • ,
  • R. A. Garcia, Université Paris-Saclay, Université Paris—Denis Diderot
  • ,
  • G. R. Davies, School of Physics and Astronomy, University of Birmingham, UK
  • ,
  • Y. Elsworth, School of Physics and Astronomy, University of Birmingham, UK
  • ,
  • R. Howe, School of Physics and Astronomy, University of Birmingham, UK

In the Sun, the frequencies of the acoustic modes are observed to vary in phase with the magnetic activity level. These frequency variations are expected to be common in solar-type stars and contain information about the activity-related changes that take place in their interiors. The unprecedented duration of Kepler photometric time-series provides a unique opportunity to detect and characterize stellar magnetic cycles through asteroseismology. In this work, we analyze a sample of 87 solar-type stars, measuring their temporal frequency shifts over segments of 90 days. For each segment, the individual frequencies are obtained through a Bayesian peak-bagging tool. The mean frequency shifts are then computed and compared with: (1) those obtained from a cross-correlation method; (2) the variation in the mode heights; (3) a photometric activity proxy; and (4) the characteristic timescale of the granulation. For each star and 90-day sub-series, we provide mean frequency shifts, mode heights, and characteristic timescales of the granulation. Interestingly, more than 60% of the stars show evidence for (quasi-)periodic variations in the frequency shifts. In the majority of the cases, these variations are accompanied by variations in other activity proxies. About 20% of the stars show mode frequencies and heights varying approximately in phase, in opposition to what is observed for the Sun.

OriginalsprogEngelsk
Artikelnummer17
TidsskriftAstrophysical Journal, Supplement Series
Vol/bind237
Nummer1
ISSN0067-0049
DOI
StatusUdgivet - 1 jul. 2018

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