Irregular changes in Hα emission line of V423 Aur observed by LAMOST Medium-Resolution Spectrographs

Abstract

Abstract We obtained seven spectra of the Be star V423 Aur on 2017 Dec. 5 using the LAMOST Medium-Resolution Spectrograph with exposures from 600 to 1200 seconds. These spectra show the irregular Hα emission line profile variations (LPVs). In the seven spectra, from the 4th to 7th, the left part of Hα profile even shows excess. However, no variation can be seen from the follow-up observation of photometry by 1.26-m telescope and High-Resolution spectra by 2.16-m telescope. According to the High-Resolution spectra, we conclude that it is a B7V type star with E(B − V) = 0.709 ± 0.036 and its v sini is ∼ 221.8 km s−1. The short-term Hα LPVs could be explained as a result of the transient ejection of matter from rotating disk or shell around V423 Aur.