High-Frequency Waves Detected in the Solar Atmosphere

Abstract

A spectrum of weakly guided waves in the solar atmosphere at frequencies as high as 100 mHz (10 s period) has been detected with high-cadence solar image sequences from the Transition Region and Coronal Explorer (TRACE) spacecraft. The waves are visible in the TRACE 1600 A far-UV passband and were detected as faint ridges in an energy spectrum produced by Fourier transformation of subfields of TRACE image sequences. They have phase speeds as high as 1 Mm s-1 and group speeds of ~100 km s-1. From the 1600 A data alone, it is not possible to determine whether the waves are in the chromosphere or transition region. The waves are not energetically significant to the chromosphere but may be significant in the transition region. Two possible excitation mechanisms, small-scale magnetic reconnection or chromospheric shock formation, are identified and will guide future work. The waves may prove to be a useful probe into local conditions and energy release into the solar atmosphere.