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arXiv · 2408.10813

Flare heating of the chromosphere: Observations of flare continuum from GREGOR and IRIS

M. García-Rivas·J. Kašparová·A. Berlicki·M. Švanda·J. Dudík·D. Čtvrtečka·M. Zapiór·W. Liu·M. Sobotka·M. Pavelková·G. G. Motorina
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Abstract

Context: On 2022 May 4, an M5.7 flare erupted in the active region NOAA 13004, which was the target of a coordinated campaign between GREGOR, IRIS, Hinode, and ground-based instruments at the Ond\v{r}ejov observatory. A flare kernel located at the edge of a pore was co-observed by the IRIS slit and GREGOR HiFI+ imagers. Aims: We investigated the flare continuum enhancement at different wavelength ranges in order to derive the temperature of the chromospheric layer heated during the flare. Methods: All datasets were aligned to IRIS slit-jaw images. We selected a pixel along the IRIS slit where the flare kernel was captured and evaluated multi-wavelength light curves within it. We defined a narrow IRIS near-UV band that comprises only continuum emission. The method, which assumes that the flare continuum enhancement is due to optically thin emission from hydrogen recombination processes, was applied to obtain a lower limit on the temperature in the layer where the continuum enhancement was formed. Results: We determined a lower limit for the temperature and its time evolution in the chromospheric layer heated during the flare in the range of (3-15).10^3 K. The mean electron density in that layer was estimated to be about 1.10^(13) cm^(-3). Conclusions: Multi-wavelength flare co-observations are a rich source of diagnostics. Due to the rapidly evolving nature of flares, the sit-and-stare mode is key to achieving a high temporal cadence that allows one to thoroughly analyse the same flare structure.

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M. García-Rivas, J. Kašparová, A. Berlicki, M. Švanda, J. Dudík, D. Čtvrtečka, M. Zapiór, W. Liu, M. Sobotka, M. Pavelková, G. G. Motorina. 2024-08-20. Flare heating of the chromosphere: Observations of flare continuum from GREGOR and IRIS. https://doi.org/10.1051/0004-6361%2F202451219

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