July 11-15, 2011
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Macroturbulent broadening: a single-snapshot alternative to investigate stellar pulsations in Massive Stars?

Sergio Simon-Diaz (Instituto de Astrofisica de Canarias)

C. Aerts, N. Castro, A. Herrero, N. Markova, J. Puls & K. Uytterhoeven

The analysis of high-resolution spectra of blue massive stars has allowed us to firmly ascertain the presence of an important non-rotational broadening in O and B-type stars of all luminosity classes (see e.g. Simon-Diaz et al. 2011, BSRSL, 80, 514). Despite it has been commonly refered to as "macroturbulent broadening", results from the analyses make its interpretation as the effect of turbulent motions quite improbable. An alternative physical mechanism suggested as the origin of this extra broadening relates to oscillations. As indicated by recent simulations by Aerts et al. (2009, A&A, 508, 409) this scenario offers a plausible explanation that is now being tested observationally (e.g. Simon-Diaz et al. 2010, ApJL, 720, 174). In this contribution, I will present our present knowledge about this intriguing line-broadening, briefly explaining the methods used to disentagle the rotational and "macroturbulent" broadening contributions to line-profiles, and summarizing the progress in our project aimed at investigating the "macroturbulent" broadening in O and B stars and its possible connection to spectroscopic variability phenomena and stellar oscillations. The following questions will be also treated in this contribution: Should be "macroturbulent" broadening actually called "pulsational" broadening? Is this spectroscopic feature a single-snapshot alternative to detect and investigate stellar pulsations in the realm of massive stars? How vsini measurements in Galactic massive stars are affected when "macroturbulent" broadening is taken into account?
(to be confirmed by the SOC)