Oscillations in the line-of-sight magnetic field strength in a solar pore
Wednesday
Abstract details
id
Oscillations in the line-of-sight magnetic field strength in a solar pore
Date Submitted
2021-04-30 12:52:00
Chris
Nelson
Queen's University Belfast
Waves and Oscillations in the Solar Atmosphere in the High-Resolution Era
Contributed
C. J. Nelson, R. J. Campbell, M. Mathioudakis
Magnetohydrodynamic oscillations have been widely reported within magnetic wave-guides over the past decades, including in diagnostics such as line-of-sight (LOS) velocities, intensities, and magnetic field strengths. In this talk, we discuss oscillations in the LOS magnetic field strength detected within a pore located in Active Region 12748 and investigate which physical mechanisms could be responsible for them. One hour of full-Stokes data from the GREGOR Infrared Spectrograph (GRIS), sampled in a 3.7 nm window containing the Fe I 1564.852 nm line (which has a Lande g-factor of 3) are analysed. The LOS magnetic field strength is estimated using the strong-field approximation (SFA) which is applied to the Stokes-V data. Additionally, the Stokes Inversion based on Response functions (SIR) code is used to gain a more complete understanding of how the physical properties of the solar atmosphere change through time at the locations of these oscillations. High-amplitude oscillations of more than 100 G are observed in the period window between 600-1272 s, in the LOS magnetic field strength at three localised (>1"^2) regions in the pore. These oscillations have some coherence across individual regions indicating that any slight changes in the pointing of the telescope cannot account for their occurrence. Longer-period amplitude variations, with amplitudes of over 200 G, are also detected but these have periods outside of the cone-of-influence of the wavelet function. Numerical inversions confirm that oscillations in the magnetic field strength at optical depths of around logtau_500=-0.5 could account for these signatures, however, other effects may also be important (e.g., changes in the optical depth or the inclination of the magnetic field).
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