Two Remarkable Spectroscopic Categories of Young O Stars from the VLT-FLAMES Tarantula Survey

Walborn, N. R.; Sana, H.; Taylor, W. D.; Simón-Díaz, S.; Evans, C. J.
Proceedings of a Scientific Meeting in Honor of Anthony F. J. Moffat held at Auberge du Lac Taureau, St-Michel-Des-Saints, Québec, Canada, held 11-15 July 2011. ASP Conference Series, Vol. 465. San Francisco: Astronomical Society of the Pacific, p.490 (2012).


The spectral and spatial characteristics of two special categories of O stars found in the VFTS dataset are presented. One of them comprises very rapid rotators, including several more extreme than any previously known. These objects are distributed around the peripheries of the main 30 Doradus clusters, suggesting a runaway nature for which their radial velocities already provide preliminary supporting evidence. The other category consists of a large number of Vz stars, previously hypothesized on spectroscopic grounds to be on or very near the ZAMS. Their distribution is the inverse of that of the rapid rotators: the Vz are strongly concentrated to the ionizing clusters, plus a newly recognized band of recent and current star formation to the north, which provides strong circumstantial evidence for their extreme youth.