The open flux evolution of a solar-mass star on the main sequence

V. See, M. Jardine, A. A. Vidotto, J. F. Donati, S. Boro Saikia, R. Fares, C. P. Folsom, S. V. Jeffers, S. C. Marsden, J. Morin, P. Petit

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)

Abstract

Magnetic activity is known to be correlated to the rotation period for moderately active mainsequence solar-like stars. In turn, the stellar rotation period evolves as a result of magnetized stellar winds that carry away angular momentum. Understanding the interplay between magnetic activity and stellar rotation is therefore a central task for stellar astrophysics. Angular momentum evolution models typically employ spin-down torques that are formulated in terms of the surface magnetic field strength. However, these formulations fail to account for the magnetic field geometry, unlike those that are expressed in terms of the open flux, i.e. the magnetic flux along which stellar winds flow. In this work, we model the angular momentum evolution of main-sequence solar-mass stars using a torque law formulated in terms of the open flux. This is done using a potential field source surface model in conjunction with the Zeeman-Doppler magnetograms of a sample of roughly solar-mass stars. We explore how the open flux of these stars varies with stellar rotation and choice of source surface radii. We also explore the effect of field geometry by using two methods of determining the open flux. The first method only accounts for the dipole component while the second accounts for the full set of spherical harmonics available in the Zeeman-Doppler magnetogram. We find only a small difference between the two methods, demonstrating that the open flux, and indeed the spin-down, of main-sequence solar-mass stars is likely dominated by the dipolar component of the magnetic field.

Original languageEnglish
Pages (from-to)536-546
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Volume474
Issue number1
Publication statusPublished - Feb 2018
Externally publishedYes

Keywords

  • Stars: activity
  • Stars: evolution
  • Stars: magnetic field
  • Stars: rotation
  • Techniques: polarimetric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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