High frequency signals in the solar atmosphere as a result of the interference between acoustic sources.
Abstract
High frequency waves in the upper layers of the solar atmosphere are believed to show a negligible amplitude when the contribution function of the spectral lines used to infer the velocity field is much larger than their characteristic wavelengths. Moreover, line formation effects in a dynamic atmosphere can mimic high frequency power due to MTF (Modulation Transfer Function) variations. We implemented a simple interference model in a numerical code which is able to simulate the pattern generated by a distribution of acoustic sources in a stratified atmosphere with various characteristic spatial scales between the sources, representative of different convection regimes. We show how interference between randomly distributed acoustic sources placed at the base of the photosphere can produce high frequency signals whose spatial distribution is constant along large vertical scales and, therefore, not suppressed by the integration along the MTF.
- Publication:
-
Memorie della Societa Astronomica Italiana Supplementi
- Pub Date:
- 2012
- Bibcode:
- 2012MSAIS..19..121S
- Keywords:
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- Waves;
- Sun: photosphere;
- Sun: Chromosphere