The relationship between coronal fan structures and oscillations above faculae regions

Abstract

The power spectra of radial-velocity and intensity oscillations are analyzed using ground-based (the Si I 10 827 A and He I 10 830 A lines) and Solar Dynamics Observatory (the Fe I 6173, 1700 A, He II 304 A, and Fe IX 171 A lines) data, with the aim of searching for frequency modes that most efficiently penetrate into the solar corona from the lower layers of solar faculae. Analysis of the spatial distribution of the oscillation power at various heights indicates that fan structures in the corona (at the height of the 171 A emission) are better reproduced at frequencies of 1–1.5 mHz. This means that oscillations with periods of 10–15 min dominate in coronal loops above faculae regions. The five-minute oscillations that universally dominate in radial-velocity measurements in low layers of faculae are appreciable in coronal loops only in individual compact fragments.