Variations of Flux Intensity in Large Features and Spectral Lines of alpha2 CVn in Ultraviolet

TL;DR

This study analyzes ultraviolet flux variations in alpha2 CVn, revealing phase-dependent differences in spectral line and feature intensities, indicating complex atmospheric flux redistribution in a magnetic chemically peculiar star.

Contribution

It provides detailed phase-resolved UV flux variation analysis of alpha2 CVn, highlighting differences in spectral feature behaviors and atmospheric flux redistribution.

Findings

Significant phase-dependent flux variations at specific UV wavelengths.

Displacement of flux minima in certain spectral lines.

Flux redistribution from inner to outer atmospheric layers.

Abstract

Variation of intensity of the flux at the cores of large features and spectral lines of the classical magnetic CP star alpha2 CVn in the ultraviolet spectral region from 1150 to 3200 A is investigated. This study is based on the archival International Ultraviolet Explorer data obtained at different phases of the rotational cycle. The shapes of two light curves at \lambda \lambda 1375 and 1415 A at the core of large feature at \lambda 1400 A curves significantly differ. The light curve at \lambda 1375 A show similar shape as in the 'pseudo-continuum'. The same behavior of the flux is at the cores of Si II resonance lines at \lambda \lambda 1260--64 and 1485 A. While, the light curve at \lambda 1415 A show the phase displacement of minimum of the flux. The phase displacement also is presented at the cores of Si II resonance lines at \lambda \lambda 1304--09 and 1485 A. The minimal values of the amplitude of the flux variations are reached at the cores of the large features at \lambda \lambda 1560 and 1770 A and at the cores of the strong Si II resonance lines. The flux at the cores of large feature at \lambda 1770 A and Fe II resonance line at \lambda 1725--31 A, within errors measurements, does not vary. The investigation of variability of the flux in the wings of Lyman-alpha line indicate that the fluxes, which formed in inner layers of atmosphere, are redistributed into outer layers of atmosphere of alpha2 CVn.