Superfast Line Profile Variations in the Spectra of OBA Stars III: A0 Star $\alpha^2\,$CVn, New Results

TL;DR

This study reports ultrafast line profile variations in the spectra of the chemically peculiar A0Vp star α² CVn, revealing short-term periodicities and magnetic field measurements, advancing understanding of stellar magnetic activity and spectral variability.

Contribution

It presents new observations of rapid line profile variations and magnetic field measurements in α² CVn, extending previous studies with higher temporal resolution and detailed magnetic analysis.

Findings

Detected periodic LPVs with periods from 4 to 140 minutes.

Measured an average magnetic field of approximately 600 G.

Confirmed magnetic field variations consistent with known phase curves.

Abstract

This work is a continuation of the studies of the ultrafast variability of line profiles in the spectra of early-type stars. Line profile variations (LPVs) in the spectrum a chemically peculiar A0Vp star $\alpha^2\,$CVn are investigated using the January 6, 2020 observations carried out with the 6-meter BTA telescope at Special Astrophysical observatory (SAO) of the Russian Academy of Sciences (RAS) equipped with the MSS spectrograph. Regular short-term periodic variations of the H$_\beta$, Fe\,II, and Cr\,II lines were detected with periods ranging from $\sim\!$4 to $\sim\!$140 minutes. The magnetic field of the star was determined for all observations. The average measured longitudinal magnetic field component over the entire duration of observations is about $\approx$600\,G, which is close to the value expected from the well-known magnetic field phase curve.