Temporal Variations of Solar Spectral Line Profiles Induced by the 5-Minute Photospheric Oscillation

摘要

The variations induced by the 5 min photospheric oscillation are simulated on the line profiles. A phase lag of the order of 150 degree between temperature and velocity wave perturbations can explain the observed differences between the oscillations of the line flanks at residual intensity levels I/I sub c < 0.7. Such a phase relation in the 5 min oscillation differs from that of the adiabatic case in which the temperature and pressure fluctuations are 90 degrees out of phase with respect to the velocity. A simple model of radiative damping in the solar photosphere can produce the required phase lag between temperature and velocity. The granulation can affect differentially the oscillations of the line flanks. This effect, however, does not fit the observed behaviour of the flank oscillations. Keywords: Solar oscillations; Line asymmetries; Line profiles; Reprints. (jhd)