| Presentation Title: | An Observational Study of the Relationship between H I Lyα and Hα/He II λ304 in an M2.0 Solar Flare |
| Author(s): | De-Chao Song, Qiao Li, Y. Li, Gen Li, Jun Tian, Hui Li, Weiqun Gan, M. D. Ding, L. Harra, L. Teriaca, R. Aznar Cuadrado, S. Parenti, K. Barczynski, A. N. Zhukov, P. J. Smith, F. Auchere, and D. Berghmans |
Abstract:
The H I Lyα at 1216 angstrom, Hα at 6563 angstrom, and He II Lyα at 304 angstrom are some of the stronger spectral lines observable in the solar atmosphere at, respectively, ultraviolet, optical, and extreme-ultraviolet wavelengths. However, their relationships have not been fully understood especially during flares due to the substantial lack of imaging observations of H I Lyα until recently. In this work, we analyse the temporal and spatial relationships between the H I Lyα and Hα/He II λ304 emissions in an M2.0 solar flare (SOL2022-03-02T17:39) observed by the Extreme Ultraviolet Imager (EUI) onboard the Solar Orbiter spacecraft, the Global Oscillation Network Group at Big Bear Solar Observatory, and the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory. The correlations between these emissions in a flaring region, in flare ribbons and in loops are presented for the first time, together with the relationships between the Sun-as-a-star irradiances for the different lines. It is found that the H I Lyα emission has a positive correlation with the He II λ304 emission in both full-disk and for targeted solar regions. By contrast, the H I Lyα and Hα correlations are different for these cases. The relationship between H I Lyα and AIA 1600 angstrom is also analysed and this shows similar behaviour to H I Lyα and Hα. These results improve our understanding of the formation and properties of these important lines in solar flares and provide some insights for studying the flaring atmospheres of Sun-like stars.