Name: Lakshitha Nama
Affiliation: CHRIST (Deemed to be University)
Conference ID : ASI2022_242
Title : Elemental abundances during the A-class solar flares: Soft X-ray spectroscopy from Chandrayaan-2 XSM
Authors : Lakshitha Nama, Biswajit Mondal, Shyama Narendranath, KT Paul
Abstract Type: Oral
Abstract Category : Sun and the Solar System
Abstract : Solar elemental abundance studies are essential to the understanding of energy and mass transport between different layers of the Sun. Elements with low (≤10 eV) First-Ionization-Potential (FIP) are seen to be two to four times more abundant in the closed-loop corona compared to the solar photosphere. This phenomenon is known as the “FIP effect” and its origin is yet to be understood well. Utilizing the soft X-ray disk-integrated spectra from Solar X-ray Monitor (XSM) onboard Chandrayaan-2, we derived the absolute abundances of low FIP elements - Mg, Al, Si, and S over the time-integrated duration of 65 A-class solar flares. The abundances of the flaring plasma are found to be near photospheric values, which contrasts with the FIP effect observed in closed loops active region cores. Further, we derived the evolution of the elemental abundances during the A-class flares using the time-resolved spectral analysis of the added spectra of multiple flares with similar lightcurve, to increase the statistical significance. It is seen that after the onset of the impulsive phase, the abundances of these four elements start decreasing from their coronal values and, during the flare peak, reach the near photospheric values. Then over the decay phase, the abundances quickly return to the pre-flare coronal values. The decrease of elemental abundances during the impulsive phase can be explained by invoking the process of chromospheric evaporation, which is consistent with the standard flare model. However, the quick recovery of the abundances in the flare decay phase is much more challenging. Such studies provide a framework to constrain the models of FIP fractionation and its evolution with plasma parameters.