Oscillations accompanying a He I 10830 {\AA} negative flare in a solar facula
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 absor...
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Zusammenfassung: | 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. |
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DOI: | 10.48550/arxiv.1810.10153 |