English

Characterizing the Motion of Solar Magnetic Bright Points at High Resolution

Solar and Stellar Astrophysics 2017-11-29 v1

Abstract

Magnetic bright points in the solar photosphere, visible in both continuum and G-band images, indicate footpoints of kilogauss magnetic flux tubes extending to the corona. The power spectrum of bright-point motion is thus also the power spectrum of Alfven wave excitation, transporting energy up flux tubes into the corona. This spectrum is a key input in coronal and heliospheric models. We produce a power spectrum of bright-point motion using radiative magnetohydrodynamic simulations, exploiting spatial resolution higher than can be obtained in present-day observations, while using automated tracking to produce large data quantities. We find slightly higher amounts of power at all frequencies compared to observation-based spectra, while confirming the spectrum shape of recent observations. This also provides a prediction for observations of bright points with DKIST, which will achieve similar resolution and high sensitivity. We also find a granule size distribution in support of an observed two-population distribution, and we present results from tracking passive tracers which show a similar power spectrum to that of bright points. Finally, we introduce a simplified, laminar model of granulation, with which we explore the roles of turbulence and of the properties of the granulation pattern in determining bright-point motion.

Keywords

Cite

@article{arxiv.1710.04738,
  title  = {Characterizing the Motion of Solar Magnetic Bright Points at High Resolution},
  author = {Samuel J. Van Kooten and Steven R. Cranmer},
  journal= {arXiv preprint arXiv:1710.04738},
  year   = {2017}
}

Comments

13 pages, 8 figures. Accepted for publication in ApJ