Multi-wavelength observations by XSM, Hinode and SDO of an active region. Chemical abundances and temperatures

TL;DR

This study combines multi-wavelength solar observations to analyze active region properties, revealing stable chemical abundances, microflare effects, and temperature diagnostics, with implications for solar physics and instrumentation calibration.

Contribution

It provides a comprehensive analysis of active region AR 12759 using coordinated XSM, AIA, Hinode XRT, and EIS data, highlighting stable chemical abundances and temperature diagnostics during microflares.

Findings

Quiescent AR core has stable temperature and chemical abundance distribution.

Low FIP elements are enhanced compared to photospheric values.

XSM spectra confirm EIS results and show microflares do not alter core abundances.

Abstract

We have reviewed the first year of observations of the Solar X-ray Monitor (XSM) onboard Chandrayaan-2, and the available multi-wavelength observations to complement the XSM data, focusing on Solar Dynamics Observatory AIA and Hinode XRT, EIS observations. XSM has provided disk-integrated solar spectra in the 1--15 keV energy range, observing a large number of microflares. We present an analysis of multi-wavelength observations of AR 12759 during its disk crossing. We use a new radiometric calibration of EIS to find that the quiescent AR core emission during its disk crossing has a distribution of temperatures and chemical abundances that does not change significantly over time. An analysis of the XSM spectra confirms the EIS results, and shows that the low First Ionization Potential (FIP) elements are enhanced, compared to their photospheric values. The frequent microflares produced by the AR did not affect the abundances of the quiescent AR core. We also present an analysis of one of the flares it produced, SOL2020-04-09T09:32. The XSM analysis indicates isothermal temperatures reaching 6 MK. The lack of very high-T emission is confirmed by AIA. We find excellent agreement between the observed XSM spectrum and the one predicted using an AIA DEM analysis. In contrast, the XRT Al-Poly / Be-thin filter ratio gives lower temperatures for the quiescent and flaring phases. We show that this is due to the sensitivity of this ratio to low temperatures, as the XRT filter ratios predicted with a DEM analysis based on EIS and AIA gives values in good agreement with the observed ones.