2024/09/11 by Takato Otsu, Ayumi Asai, Otsu, Takato +5 · 7 citations
Earth and Planetary Sciences · Physics and Astronomy · #Atmospheric Ozone and Climate #FOS: Physical sciences #Solar and Space Plasma Dynamics #Solar and Stellar Astrophysics (astro-ph.SR)
paper · pdf · doi:10.48550/arxiv.2409.07630
openalex publication_date 2024/09/11 · openalex created_date 2024/10/23 · openalex updated_date 2026/07/28
Post-flare loops are loop-like plasmas observed during the decay phase of solar flares, and they are expected to exist for stellar flares. However, it is unclear how post-flare loops are observed in stellar flares' cases. To clarify behaviors of post-flare loops in spatially integrated data, we performed the Sun-as-a-star analysis of the X1.6 flare that occurred on 2023 August 5, using GOES X-ray flux (∼107 K), extreme ultraviolet (EUV) images taken by Atmospheric Imaging Assembly onboard the Solar Dynamic Observatory (≥104.9 K) and Hα data taken by Solar Dynamics Doppler Imager on board the Solar Magnetic Activity Research Telescope at Hida Observatory, Kyoto University (∼104 K). As a result, this flare showed signatures corresponding to the important dynamics of the post-flare loops even in the spatially integrated data: (1) The Hα light curve showed two distinct peaks corresponding to the flare ribbons and the post-flare loops. The plasma cooling in the post-flare loops generated different peak times in soft X-rays, EUV, and Hα light curves. (2) Downflows were confirmed as simultaneous redshifted/blueshifted absorptions in the Hα spectra. (3) The apparent rise of post-flare loops was recognized as a slowing of the decay for the Hα light curve. These results are keys to investigating stellar post-flare loops with spatially integrated data. We also discuss the dependence of our results on flare locations and their possible applications to stellar observations.