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Elements with low First Ionization Potential (FIP) are known to be three tofour times more abundant in active region loops of the solar corona than in thephotosphere. There have been observations suggesting that this observed "FIPbias" may be different in other parts of the solar corona and such observationsare thus important in understanding the underlying mechanism. The Solar X-rayMonitor (XSM) on board the Chandrayaan-2 mission carried out spectroscopicobservations of the Sun in soft X-rays during the 2019-20 solar minimum,considered to be the quietest solar minimum of the past century. Theseobservations provided a unique opportunity to study soft X-ray spectra of thequiescent solar corona in the absence of any active regions. By modelling highresolution broadband X-ray spectra from XSM, we estimate the temperature andemission measure during periods of possibly the lowest solar X-ray intensity.We find that the derived parameters remain nearly constant over time with atemperature around 2 MK, suggesting the emission is dominated by X-ray BrightPoints (XBPs). We also obtain the abundances of Mg, Al, and Si relative to H,and find that the FIP bias is ~2, lower than the values observed in activeregions.

the astrophysical journal. letters

Observations of the Quiet Sun During the Deepest Solar Minimum of the  Past Century with Chandrayaan-2 XSM -- Elemental Abundances in the Quiescent  Corona