Diagnostics of temperature and blue-shifted velocity using soft X-ray spectra from the Macau Science Satellite-1

Using the new soft X-ray data from the Macau Science Satellite-1, we studied a solar flare that occurred on 22 June 2023. We found that the centroids of the Ca (around 3.9 keV) and Fe (around 6.7 keV) line features exhibit a rapid shift toward higher energy channels during the flare's rising phase, followed by a gradual decrease during the decay phase. Through precise energy calibration, the centroids are determined with high accuracy. Temperature and velocity are then self-consistently derived by comparing the centroids with those calculated from the synthesized line features using the latest CHIANTI atomic database (ver. 10.1). The calculated maximum velocity reaches up to 710 ± 60 km s⁻¹, which significantly exceeds the previously reported values. Our results suggest that the entire shift of soft X-ray lines may occur during the process of chromospheric evaporation.