Letter to the Editor

Evidence for short-period acoustic waves in the solar atmosphere

¹ Universitäts-Sternwarte, Geismarlandstraße 11, 37083 Göttingen, Germany
² Institut für Geophysik, Astrophysik und Meteorologie, Universitätsplatz 5, 8010 Graz, Austria

Corresponding author: M. Wunnenberg, wunnenbe@uni-sw.gwdg.de

Received: 27 September 2002
Accepted: 17 October 2002

Abstract

Short-period acoustic waves are thought to supply the energy for the radiative losses of the non-magnetic chromosphere of the Sun and, in general, of late-type stars. Here, we present evidence for the existence of waves in the solar atmosphere with periods in the range of 50 s  100 s. Two-dimensional time sequences with a cadence of 25 s were obtained from quiet Sun disk center in Fe i 5434 Å. The observations were performed with the “Göttingen” Fabry-Perot spectrometer in the Vacuum Tower Telescope at the Observatorio del Teide/Tenerife. They are subjected to speckle reconstruction and to a wavelet analysis. The atmospheric ranges forming the velocity signals are narrowed by linear combinations of Doppler maps from wavelengths near line center. The power in the short-period range is concentrated above intergranular spaces. We estimate an acoustic flux into the chromosphere of approximately 3 erg cm^-2 s^-1, as needed for the chromospheric radiative losses.