Oscillations Accompanying a He i 10830 Å Negative Flare in a Solar Facula

Abstract

On September 21, 2012, we carried out spectral observations of a solar facula in the Si I 10827 {\AA}, He I 10830 {\AA}, and H{\alpha} spectral lines. Later, in the process of analyzing the data, we found a small-scale flare in the middle of the time series. Due to an anomalous increase in the absorption of the He I 10830 {\AA} line, we identified this flare as a negative flare. The aim of this paper is to study the influence of the negative flare on the oscillation characteristics in the facular photosphere and chromosphere. We measured line-of-sight (LOS) velocity and intensity of all the three lines as well as half-width of the chromospheric lines. We also used SDO/HMI magnetic field data. The flare caused modulation of all the studied parameters. In the location of the negative flare, the amplitude of the oscillations increased four times on average. In the adjacent magnetic field local maxima, the chromospheric LOS velocity oscillations appreciably decreased during the flare. The facula region oscillated as a whole with a 5-minute period before the flare, and this synchronicity was disrupted after the flare. The flare changed the spectral composition of the line-of-sight magnetic field oscillations, causing an increase in the low-frequency oscillation power.