Evidence for short-period acoustic waves in the solar atmosphere

Free access article

Issue		A&A Volume 395, Number 3, December I 2002


Page(s)		L51 - L54
Section		Letters
DOI		http://dx.doi.org/10.1051/0004-6361:20021531

A&A 395, L51-L54 (2002)
DOI: 10.1051/0004-6361:20021531

Letter

Evidence for short-period acoustic waves in the solar atmosphere

M. Wunnenberg¹, F. Kneer¹ and J. Hirzberger²

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

(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 <P< 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 $\times10^6$ erg cm ^-2 s ^-1, as needed for the chromospheric radiative losses.

Key words: waves -- Sun: photosphere -- Sun: chromosphere

Offprint request: M. Wunnenberg, wunnenbe@uni-sw.gwdg.de

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