Irregular changes in H{\alpha} emission line of V423 Aur observed by LAMOST Medium-Resolution Spectrographs

TL;DR

This study reports irregular H-alpha emission line profile variations in the Be star V423 Aur, observed with LAMOST, suggesting transient matter ejection from its rotating disk as a possible cause.

Contribution

First detailed spectroscopic observation of V423 Aur showing irregular H-alpha LPVs with analysis indicating transient ejections.

Findings

Irregular H-alpha LPVs observed in V423 Aur.

No photometric or high-res spectral variation detected.

Transient ejection likely causes the LPVs.

Abstract

We obtained 7 spectra of the Be star V423 Aur on Dec. 5th, 2017 using the LAMOST Medium-Resolution Spectrograph with exposures from 600 to 1200 seconds. These spectra show the irregular H{\alpha} emission line profile variations (LPVs). In the seven spectra, from the 4th to 7th, the left part of H{\alpha} profile even show 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{\pm}0.036 and its vsini is {\sim} 221.8km/s. The short-term H{\alpha} LPVs could be explained as a result of the transient ejection of matter from rotating disk or shell around V423 Aur.