Photospheric and Chromospheric Oscillations in Solar Faculae

Abstract

The differences between physical conditions in solar faculae and those in sunspots and quiet photosphere (increased temperature and different magnetic field topology) suggest that oscillation characteristics in facula areas may also have different properties. The analysis of 28 time series of simultaneous spectropolarimetric observations in facula photosphere (Fe i 6569 A, 8538 A) and chromosphere (Hα, Ca ii 8542 A) yields the following results. The amplitude of five-minute oscillations of line-of-sight (LOS) velocity decreases by 20 – 40% in facula photosphere. There are only some cases revealing the inverse effect. The amplitude of four- to five-minute LOS velocity oscillations increases significantly in the chromosphere above faculae, and power spectra fairly often show pronounced peaks in a frequency range of 1.3 – 2.5 mHz. Evidence of propagating oscillations can be seen from space – time diagrams. We have found oscillations of the longitudinal magnetic field (1.5 – 2 mHz and 5.2 mHz) inside faculae.