The impact of macro and microturbulent broadenings in measurements of rotational velocities in Galactic OB stars

Stellar rotation is an important parameter in the evolution of massive stars, as it plays a major role in shaping their structure, the surface abundance pattern, and the final fate of these stars. Projected rotational velocities of stars can be measured from the broadening that rotation produces on the spectral line profiles. However, this is not straightforward since other sources of line-broadening may be taking part.

Recently, Sergio Simón-Díaz (SO Postdoc) and Artemio Herrero, researchers of the IAC and the University of La Laguna, have investigated the impact of macroturbulent and microturbulent broadenings on measurements of projected rotational velocities for a sample of ~200 Galactic OB-type stars. Their results confirm that the macroturbulent broadening is ubiquitous in the massive-star domain, and that both effects should be taken into account in order to recover the correct distributions of projected rotational velocities in Galactic OB-type stars.

This study makes use of the IACOB spectroscopic survey of Galactic OB stars, an ambitious observational project that have compiled a large, homogeneous, high-resolution database of optical spectra of massive stars observable from the Northern hemisphere.

More information: Simón-Díaz & Herrero 2014, A&A 562, A135