Oscillations in the Solar Faculae. III. The Phase Relations between Chromospheric and Photospheric LOS Velocities

Abstract

An analysis of line-of-sight velocity oscillation in nine solar faculae was undertaken with the aim of studying of phase relations between chromosphere (He i 10830 A line) and photosphere (Si i 10827 A line) five-minute oscillations. We found that time lag of the chromospheric signal relative to photospheric one varies from -12 to 100 seconds and is about 50 seconds on average.We assume that the small observed lag can have three possible explanations: i) convergence of formation levels of He i 10830 A and Si i 10827 A in faculae; ii) significant increase of five-minute oscillation propagation velocity above faculae; iii) simultaneous presence of standing and travelling waves.