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arXiv · 2007.11594

Magnetoacoustic Wave Energy Dissipation in the Atmosphere of Solar Pores

Caitlin A. Gilchrist-Millar·David B. Jess·Samuel D. T. Grant·Peter H. Keys·Christian Beck·Shahin Jafarzadeh·Julia M. Riedl·Tom Van Doorsselaere·Basilio Ruiz Cobo
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Abstract

The suitability of solar pores as magnetic wave guides has been a key topic of discussion in recent years. Here we present observational evidence of propagating magnetohydrodynamic wave activity in a group of five photospheric solar pores. Employing data obtained by the Facility Infrared Spectropolarimeter at the Dunn Solar Telescope, oscillations with periods on the order of 5 minutes were detected at varying atmospheric heights by examining Si I 10827 Å line bisector velocities. Spectropolarimetric inversions, coupled with the spatially resolved root mean square bisector velocities, allowed the wave energy fluxes to be estimated as a function of atmospheric height for each pore. We find propagating magnetoacoustic sausage mode waves with energy fluxes on the order of 30 kW/m$^{2}$ at an atmospheric height of 100 km, dropping to approximately 2 kW/m$^{2}$ at an atmospheric height of around 500 km. The cross-sectional structuring of the energy fluxes reveals the presence of both body- and surface-mode sausage waves. Examination of the energy flux decay with atmospheric height provides an estimate of the damping length, found to have an average value across all 5 pores of $L_d \approx 268$km, similar to the photospheric density scale height. We find the damping lengths are longer for body mode waves, suggesting that surface mode sausage oscillations are able to more readily dissipate their embedded wave energies. This work verifies the suitability of solar pores to act as efficient conduits when guiding magnetoacoustic wave energy upwards into the outer solar atmosphere.

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Caitlin A. Gilchrist-Millar, David B. Jess, Samuel D. T. Grant, Peter H. Keys, Christian Beck, Shahin Jafarzadeh, Julia M. Riedl, Tom Van Doorsselaere, Basilio Ruiz Cobo. 2020-07-22. Magnetoacoustic Wave Energy Dissipation in the Atmosphere of Solar Pores. https://doi.org/10.1098/rsta.2020.0172

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