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Paper: Chromospheric Oscillations Observed by SUMER/SOHO
Volume: 184, Third Advances in Solar Physics Euroconference: Magnetic Fields and Oscillations
Page: 201
Authors: Heinzel, P.; Curdt, W.
Abstract: We discuss first observations of the temporal behaviour of the hydrogen Lyman lines made by the SUMER/SOHO spectrometer. Using the Ly 5 line, we show here the global oscillatory pattern of the whole line profile for three representative quiet-Sun structures: cell interior, network boundary, and bright network. Mean power spectra for these structures show several maxima, some of which are quite well correlated with the maxima derived from Ca II K_2V observations. In the cell interior, the power peak is centred between 4.5-5 mHz. No clear evidence of a 3 minute chromospheric mode was found. In the network, we observe a broad range of frequencies, with a maximum between 2-3 mHz. Lyman lines exhibit certain Doppler shifts and asymmetries, but the oscillatory behaviour is mainly due to the intensity variations which are small compared to the line intensity itself (they reach 10-20 % of the mean line intensity).
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