PREDNASAJUCI / LECTURER :

Zurab Vashalomidze

(1) Astronomical Institute, Slovak Academy of Sciences,
059 60 Tatranská Lomnica

NAZOV / TITLE :

Infrared spectropolarimetry of a C-class solar flare footpoint plasma

ABSTRAKT / ABSTRACT :

We performed full Stokes spectropolarimetric observations of plasma near loop footpoints in the active region NOAA 3363
during a C-class flare using the GREGOR infrared spectrograph (GRIS) on July 16 2023. The near-infrared spectral interval
covered photospheric Si I 10827A and Ca I 10839A lines and chromospheric He I 10830A triplet line. In addition to the
enhanced emission of the He I 10830A triplet, the upper photospheric line Si I 10827A also showed a significant increase
in intensity. For the first time ever, we document the intensity of the Si I line increased several minutes after the He I
enhancement, which indicates slow energy transfer from the chromosphere to the upper photosphere. We speculate that heat
transfer by thermal conduction from the formation height of the He I to the formation height of the Si I line is responsible
for the observed time delay.