Journal
ASTROPHYSICAL JOURNAL
Volume 850, Issue 1, Pages -Publisher
IOP PUBLISHING LTD
DOI: 10.3847/1538-4357/aa93e2
Keywords
convection; magnetohydrodynamics (MHD); Sun: granulation; Sun: photosphere; waves
Categories
Funding
- NSF [1613207, 1540094]
- NASA [NNX15AW33G, NNX16AG87G]
- Department of Astrophysical and Planetary Sciences at the University of Colorado Boulder
- National Science Foundation [ACI-1532235, ACI-1532236]
- University of Colorado Boulder
- Colorado State University
- Directorate For Geosciences
- Div Atmospheric & Geospace Sciences [1540094] Funding Source: National Science Foundation
- Division Of Astronomical Sciences
- Direct For Mathematical & Physical Scien [1613207] Funding Source: National Science Foundation
- NASA [904840, NNX16AG87G] Funding Source: Federal RePORTER
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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.
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