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

TL;DR

This study investigates the phase relations between chromospheric and photospheric velocity oscillations in solar faculae, revealing variable time lags that suggest complex wave interactions and propagation dynamics.

Contribution

It provides new insights into the phase relations and time lags of five-minute oscillations between the chromosphere and photosphere in solar faculae, highlighting possible wave propagation mechanisms.

Findings

Time lag varies from -12 to 100 seconds, averaging about 50 seconds.

Small lag may be due to convergence of formation levels or wave dynamics.

Presence of standing and traveling waves in faculae observed.

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.