[P-EM11] Frontiers in solar physics

[PEM11-P04] Effects of Ionization Nonequilibrium on First Ionization Potential (FIP) Bias during Solar Flares

*小宮山 颯音¹、今田 晋亮¹、庄田 宗人¹ (1.東京大学)

Solar flares are one of the largest energy release events in the solar system and are known to dramatically change the plasma in the solar earth environment in a short period of time. It is known that the composition ratio of the plasma that makes up the solar corona is also changed by solar flares, and the composition ratio of the corona is closer to that of the photosphere than usual. On the other hand, when we analyze the FIP bias effect from the observation of the normal solar corona and consider the composition ratio, it is necessary to assume ionization equilibrium, which raises a question whether we can assume ionization equilibrium when dealing with very dynamic phenomena. We performed 1D numerical simulations of chromospheric evaporation with ionization processes in order to investigate the influence of ionization nonequilibrium on the FIP Bias effect during solar flares. From these simulations, we estimated the emission line pairs of FeXVI and SXIII, CaXIV and ArXIV, which are used in the analysis of the FIP Bias effect during normal observations.
The results show that the FIP Bias effect is significantly underestimated in the early stages of solar flares when ionization nonequilibrium is not taken into account. In this talk, I will discuss the results of the time evolution taking into account the spatial structure of the solar flare loop. The obtained results may be able to explain the Inverse FIP effect and will be discussed in the future.