Collective pulsational velocity broadening due to gravity modes as a physical explanation for macroturbulence in hot massive stars

Abstract

We aimed at finding a physical explanation for the occurrence of macroturbulence in the atmospheres of hot massive stars, a phenomenon found in observations since more than a decade but yet unexplained. We computed time series of line profiles for evolved massive stars broadened by rotation and by hundreds of low-amplitude nonradial gravity-mode pulsations which are predicted to be excited for evolved massive stars. In general, line profiles based on macrotubulent broadening can mimic those subject to pulsational broadening. In several cases, though, good fits require macroturbulent velocities that pass the speed of sound for realistic pulsation amplitudes. Moreover, we find that the rotation velocity can be seriously underestimated by using a simple parameter description for macroturbulence rather than an appropriate pulsational model description to fit the line profiles. We conclude that macroturbulence is a likely signature of the collective effect of pulsations. We provide line diagnostics and their typical values to decide whether or not pulsational broadening is present in observed line profiles, as well as a procedure to avoid an inaccurate estimation of the rotation velocity.

12 pages, 9 figures, accepted for publication by Astronomy and Astrophysics

References in corpus (15)

• The VLT-FLAMES survey of massive stars: atmospheric parameters and rotational velocity distributions for B-type stars in the Magellanic Clouds
• Bright OB stars in the Galaxy IV. Stellar and wind parameters of early to late B supergiants
• Asteroseismology and Interferometry
• The Liege Oscillation Code
• Abundance analysis of prime B-type targets for asteroseismology I. Nitrogen excess in slowly-rotating beta Cephei stars
• Statistical properties of a sample of periodically variable B-type supergiants - Evidence for opacity-driven gravity-mode oscillations
• Most Detects G- and P-Modes in the B Supergiant HD 163899 (B2Ib/II)
• Evidence for nonlinear resonant mode coupling in the Beta Cep star HD 180642 (V1449 Aql) from CoRoT space-based photometry
• Instability strips of SPB and beta Cephei stars: the effect of the updated OP opacities and of the metal mixture
• CoRoT's view of newly discovered B-star pulsators: results for 358 candidate B pulsators from the initial run's exoplanet field data
• Bisectors of the cross-correlation function applied to stellar spectra. Discriminating stellar activity, oscillations and planets
• Pulsations detected in the line profile variations of red giants: Modelling of line moments, line bisector and line shape
• Automated supervised classification of variable stars II. Application to the OGLE database
• Ground-based observations of the beta Cephei CoRoT main target HD 180642: abundance analysis and mode identification
• Wind structure of late B supergiants I. Multi-line analyses of near-surface and wind structure in HD 199 478 (B8 Iae)

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