The nature of the line profile variability in the spectrum of the massive binary HD 152219

Abstract

HD 152219 is a massive binary system with O9.5 III + B1-2 V/III components and a short orbital period of 4.2 d. Its primary component further displays clear line profile variability (LPV). The primary component being located within the pulsational instability domain predicted for high-luminosity stars, we previously suggested that the observed LPV could be associated with non-radial pulsations. The aim of the present work is to determine the nature of the observed LPV in the spectrum of the primary component of HD 152219.During a 4-night FEROS monitoring campaign, we collected a new set of 134 high signal-to-noise spectra. These new observations were then used to re-investigate the variability of different line profiles in the spectrum of HD 152219. Based on the present analysis, we discard the non-radial pulsations and point out the Rossiter-McLaughlin effect as the cause of the LPV in HD 152219. The upper limit on the amplitude of possible weak pulsations is set at a few parts per thousand of the continuum level.