Authors: Yu Xu (Peking Univeristy), Hui Tian (Peking University), Julián Alvarado-Goméz (Astrophysics Institute Potsdam)

Coronal mass ejections (CMEs) on the hosting stars are considered to be one of the decisive factors that affect the habitability of its orbiting planets. The propagation direction and true velocity of a CME are among the most decisive factors for its effectiveness. We show that Sun-as-a-star spectroscopic observations, together with imaging observations to derive the true velocity of a solar eruption. Using observations of SDO/EVE (Extreme Ultraviolet Variability Experiment), we found clear blueshifted secondary emission components in extreme-ultraviolet spectral lines during a solar eruption on 2021 Oct. 28.

The stellar CMEs on solar-type stars are studied using simulations. We conducted MHD simulations of stellar CMEs on late-type stars using the Space Weather Modeling Framework (SWMF). We traced the propagation and evolution of CMEs in the 3D outputs. Coronal dimming/brightening are shown on the synthetic EUV images in different passbands. Line profiles of several EUV and soft X-ray lines are synthesized. Doppler shifts or the red-blue wing asymmetry, and their developments are seen during the launch and early propagation of CMEs. Our investigations set constrains on the detectability of stellar CMEs through line asymmetries and provide guidelines for the future search of stellar CMEs.