Open AccessTime signatures of impulsively generated coronal fast wave trains
Author(s) -
Nakariakov V. M.,
Arber T. D.,
Ault C. E.,
Katsiyannis A. C.,
Williams D. R.,
Keenan F. P.
Publication year - 2004
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2004.07537.x
Subject(s) - physics , amplitude , transverse plane , train , wavelet , spectral density , computational physics , waveform , coronal loop , optics , astrophysics , coronal mass ejection , solar wind , plasma , statistics , cartography , mathematics , structural engineering , quantum mechanics , voltage , artificial intelligence , computer science , geography , engineering
Impulsively generated short‐period fast magneto‐acoustic wave trains, guided by solar and stellar coronal loops, are numerically modelled. In the developed stage of the evolution, the wave trains have a characteristic quasi‐periodic signature. The quasi‐periodicity results from the geometrical dispersion of the guided fast modes, determined by the transverse profile of the loop. A typical feature of the signature is a tadpole wavelet spectrum: a narrow‐spectrum tail precedes a broad‐band head. The instantaneous period of the oscillations in the wave train decreases gradually with time. The period and the spectral amplitude evolution are shown to be determined by the steepness of the transverse density profile and the density contrast ratio in the loop. The propagating wave trains recently discovered with the Solar Eclipse Coronal Imaging System (SECIS) instrument are noted to have similar wavelet spectral features, which strengthens the interpretation of SECIS results as guided fast wave trains.