Speaker
Description
First Name: Beili
Last Name: Ying
Affiliation: Purple Mountain Observatory, Chinese Academy of Sciences
All Authors: Beili Ying, Li Feng, Shuting Li, Guanglu Shi
Abstract: As one of the most significant eruptive phenomena in the solar atmosphere, the temperature evolution of coronal mass ejections (CMEs) is a key parameter for understanding their physical processes. The differential emission measure (DEM) method is commonly used to derive the electron temperature of CMEs. However, due to the limit of observation passbands—such as the six extreme ultraviolet (EUV) channels of SDO/AIA—DEM analysis typically reflects only the high-temperature structures of CMEs. Moreover, the signal-to-noise ratio near the solar limb is often low, leading to less reliable temperature diagnostics and a field of view mainly restricted to the low corona. The SOHO/UVCS spectrometer previously provided abundant CME observations and temperature diagnostics in the middle corona, but it ceased operation in 2012 and offered only a narrow slit view, making it difficult to trace CME evolution. The Lyman-α Solar Telescope (LST) onboard the Chinese ASO-S satellite provides simultaneous white-light (WL) and UV (neutral hydrogen H I 121.6 nm) observations of the middle corona from 1.1 to 2.5 solar radii, similar to the Metis coronagraph onboard the Solar Orbiter satellite, but complementary in terms of orbit and field of view. In this presentation, we will introduce the methods and recent progress in diagnosing CME temperatures based on combined WL and UV observations. This temperature diagnostic technique is applied for the first time to the dual-band observations from ASO-S/LST, yielding preliminary results on the evolution of physical parameters of a CME in the middle corona.