Detectability of High Frequency Acoustic Waves with Trace

Abstract

High frequency acoustic waves have been proposed as a mechanism to heat the solar chromosphere in internetwork regions. Such waves are di cult to detect using ground based observations because of seeing. Space based solar observatories like SOHO and TRACE are not hampered by such high frequency disturbances caused by the Earth’s atmosphere. We have used detailed NLTE radiation hydrodynamic simulations to investigate the detectability of high frequency acoustic waves with TRACE. A broad spectrum of acoustic waves are fed into the computational domain at the lower boundary of the model atmosphere and TRACE UV continuum intensities are calculated by folding the derived intensities with the TRACE filter functions for the 1600 and 1700 Å filters. Power spectra, phase diagrams and intensity response functions are calculated and intensity formation heights are derived. The simulations show that the width of the TRACE intensity response functions sets an upper frequency limit of 40 mHz for the detection of high frequency waves even in the absence of instrumental noise.