Spectral Classification and Properties of the OVz Stars in the Galactic O Star Spectroscopic Survey (GOSSS)

SIMON DIAZ, S.; SABIN-SANJULIAN, C; SOTA, A; LEAO, J.R.S.; WALBORN, N.R.; MAIZ APELLANIZ, J; MORRELL, N.I.; NEGUERUELA, I.; ALFARO, E.J.; ARIAS, J.I.; BARBA, RODOLFO H; GAMEN, R. C.; MARCO, A.; HERRERO, A.

ASTRONOMICAL JOURNAL

IOP PUBLISHING LTD

Lugar: Londres; Año: 2016 vol. 152 p. 31 - 49

0004-6256

On the basis of the Galactic O Star Spectroscopic Survey (GOSSS), we present a detailed systematic investigation of the O Vz stars. The currently used spectral classification criteria are rediscussed, and the Vz phenomenon is recalibrated through the addition of a quantitative criterion based on the equivalent widths of the He i λ4471, He ii λ4542, and He ii λ4686 spectral lines. The GOSSS O Vz and O V populations resulting from the newly adopted spectral classification criteria are comparatively analyzed. The locations of the O Vz stars are probed, showing a concentration of the most extreme cases toward the youngest star-forming regions. The occurrence of the Vz spectral peculiarity in a solar-metallicity environment, as predicted by the fastwind code, is also investigated, confirming the importance of taking into account several processes for the correct interpretation of the phenomenon.