Halpha spectra of UX Ari

We report the capture of a filament eruption associated with an optical flare on the RS CVn-type star UX Ari. Based on high-resolution spectroscopic observations, we investigated the Doppler-shifted absorption features appeared in the H{alpha} flaring spectra, which can be indicative of a filament eruption.

A huge optical flare was observed, which lasted for at least 150 hours and released an energy of about 1.47x10^37^erg in the H{alpha} line. The corresponding bolometric white-light energy is converted to be 1.03x10^39^erg, indicating that the flare is comparable to the most intense stellar superflares. A blueshifted absorption feature with a bulk velocity of -143.9km/s emerged in the H{alpha} line region during the initial phase of the flare, which then decelerated and turned into redshifted absorption.