Acoustic waves in the solar atmosphere at high spatial resolution. II. Measurement in the Fe I 5434 Å line
Abstract
Aims: We investigate the energy supply of the solar chromosphere by acoustic waves.
Methods: A time sequence with high spatial and temporal resolution from the quiet Sun disc centre in Fe i 5434 Å (Landé factor g = 0) is analysed. We used models from a numerical simulation of granular convection and apply NLTE spectral line transfer to determine the height of formation. For estimates of acoustic energy flux, we adopted wave propagation with inclinations of the wave vector with respect to the vertical of 0°, 30°, and 45°. For a granular and an intergranular model, the transmissions of the atmosphere to highfrequency waves were determined for the three inclination angles. Wavelet and Fourier analyses were performed and the resulting power spectra were corrected for atmospheric transmission.
Results: We find waves with periods down to ~40 s. They occur intermittently in space and time. The velocity signal is formed at a height of 500 km in the granular model and at 620 km in the intergranule. At periods shorter than the acoustic cutoff (~190 s), ~40% of the waves occur above granules and ~60% above intergranules. By adopting vertical propagation, we estimate total fluxes above granules of 27503360 W m^{2}, and of 9101 000 W m^{2} above intergranules. The weighted average is 17302 060 W m^{2}. The estimates of the total fluxes increase by 15% when inclined wave propagation of 45° is assumed.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 November 2010
 DOI:
 10.1051/00046361/201014052
 Bibcode:
 2010A&A...522A..31B
 Keywords:

 Sun: chromosphere;
 Sun: oscillations;
 techniques: spectroscopic;
 Sun: photosphere