Detection of high-frequency oscillations and damping from multi-slit spectroscopic observations of the corona

Abstract

During the total solar eclipse of 11 July 2010, multi-slit spectroscopic observations of the solar corona were performed from Easter Island, Chile. To search for highfrequency waves, observations were taken at a high cadence in the green line at 5303 Å that is due to [Fe XIV] and the red line at 6374 Å that is due to [Fe X]. The data were analyzed to study the periodic variations in intensity, Doppler velocity, and line width using wavelet analysis. The data with high spectral and temporal resolution enabled us to study the rapid dynamical changes within coronal structures. We find that at certain locations, each parameter shows significant oscillation with periods ranging from 6 – 25 s. For the first time, we were able to detect damping of high-frequency oscillations with periods of about 10 s. If the observed damped oscillations are due to magnetohydrodynamic waves, then they can contribute significantly to the heating of the corona. From a statistical study we try to characterize the nature of the observed oscillations while considering the distribution of power in different line parameters.