Is macroturbulent broadening in OB Supergiants related to pulsations?
S. Simón-Díaz (1), K. Uytterhoeven, A. Herrero, N. Castro, J. Puls, C. Aerts
(1) Instituto de Astrofísica de Canarias (Spain)
The spectrum of O and B Supergiants is known to be affected by an important extra line-broadening (usually called macroturbulence) that adds to stellar rotation. Recent analysis of high resolution spectra has shown that the interpretation of this line-broadening as a consequence of large-scale turbulent motions would imply highly super-sonic velocity fields, making this scenario quite improbable. Stellar oscillations have been proposed as a likely alternative explanation. We present first encouraging results of an observational project aimed at investigating the macroturbulent broadening in O and B Supergiants, and its possible connection with spectroscopic variability phenomena and stellar oscillations: a) all the studied B Supergiants show line profile variations, quantified by means of the first (< v >) and third velocity (< v^3 >) moments of the lines, b) there is a strong correlation between the peak-to-peak amplitudes of the < v > and < v^3 > variability and the size of the extra-broadening.
Status: Conference proceedings
Comments: Proceeding of the IV Helas International Conference: "Seismological challeges for stellar structure". Editors:Teodoro Roca Cortés, Pere Pallé and Sebastián Jiménez Reyes