Line-profile variability from tidal flows in alpha virginis (SPICA)

Abstract

We present the results of high precision, high-resolution (R ∼ 68,000) optical observations of the short-period (4 days) 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 signal-to-noise ratio > 2000 line profiles at full spectral resolution in the wavelength range Δλ4000-8500 Å, 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. © 2009. The American Astronomical Society. All rights reserved.