Speaker
Description
First Name: Michalina
Last Name: Litwicka
Affiliation: University of Wrocław, Centre of Scientific Excellence – Solar and Stellar Activity, Joliot-Curie 12, PL-50-383 Wrocław, Poland
All Authors: Litwicka Michalina, Berlicki Arkadiusz, Heinzel Petr, Mrozek Tomasz
Abstract: Radiation–hydrodynamic (RHD) simulations of solar flare chromospheric emission are complex and require high-quality observations covering both hard X-rays and UV/optical parts of the solar spectrum. Two instruments, STIX and IRIS, are capable of simultaneous observations of the Sun. Among the available events, we selected the X9 flare on 3 October 2024, observed by STIX, IRIS and CHASE. IRIS recorded it in sit-and-stare mode with a 0.8 s cadence, providing Mg II k line profiles evolution suitable for modeling. The crucial challenge is building a heating model capable of reproducing the observed spectra. Many existing RHD simulations overestimate line intensities. In the recent paper by Tamburi et al. (2025), the authors showed using DKIST observations, that Hα flare loops can be thinner than 50 km, suggesting unresolved multithreaded structure. Motivated by this, we compared two approaches in the RHD code FLARIX simulations: (1) a standard model with continuous nonthermal-electron heating, and (2) a filamentary model with a short electron-beam pulses in unresolved threads. The filamentary scenario yields Hα and Mg II k intensities more consistent with observations. Our goal is to construct such a filamentary heating model for the observed flare.