The flux of Alfvén waves in sunspots.
Abstract
Spectrographic observations of a large sunspot are used to derive the flux of Alfven waves in the spot's photosphere under the assumption that the horizontal velocities observed in the photosphere of a sunspot are caused by Alfven waves. Profiles of the Ti I (5713.90 A) and Fe I (5691.50) absorption lines are analyzed to determine the amount of nonthermal motion in the spot, and it is concluded that the line widths are entirely consistent with the hypothesis of sunspot cooling by Alfven waves. The wave flux in the spot's photosphere is found to be equal to 20% to 50% of the missing sunspot energy flux, or two to three times the spot's flux of electromagnetic energy.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 1976
- DOI:
- 10.1086/154135
- Bibcode:
- 1976ApJ...203..739B
- Keywords:
-
- Magnetohydrodynamic Waves;
- Photosphere;
- Plasma Flux Measurement;
- Solar Spectra;
- Sunspots;
- Absorption Spectra;
- Graphs (Charts);
- Light Scattering;
- Line Spectra;
- Radiation Pressure;
- Solar Flux;
- Spectrum Analysis;
- Solar Physics