Line-profile variability from tidal flows in Alpha Virginis (Spica)

TL;DR

This study uses high-resolution optical observations of Spica to analyze how tidal interactions induce surface flows, causing observable line-profile variability, with results supported by theoretical calculations.

Contribution

It provides detailed observational evidence linking tidal effects to surface flows and line-profile variability in a binary system, supported by theoretical modeling.

Findings

Line-profile variability is caused by tidal-induced surface flows.

High S/N data reveals variability on ~2 hour timescales.

Theoretical calculations support tidal interaction as the variability source.

Abstract

We present the results of high precision, high resolution (R~68000) optical observations of the short-period (4d) eccentric binary system Alpha Virginis (Spica) showing the photospheric line-profile variability that in this system can be attributed to non-radial pulsations driven by tidal effects. Although scant in orbital phase coverage, the data provide S/N>2000 line profiles at full spectral resolution in the wavelength range delta-lambda = 4000--8500 Angstroms, allowing a detailed study of the night-to-night variability as well as changes that occur on ~2 hr timescale. Using an ab initio theoretical calculation, we show that the line-profile variability can arise as a natural consequence of surface flows that are induced by the tidal interaction.