Arias, Julia I.;Walborn, Nolan R.;Simón Díaz, Sergio;Barbá, Rodolfo H.;Maíz Apellániz, Jesús;Sabín-Sanjulián, Carolina;Gamen, Roberto C.;Morrell, Nidia I.;Sota, Alfredo;Marco, Amparo;Negueruela, Ignacio;Leão, João R. S.;Herrero, Artemio;Alfaro, Emilio J. 2016. Spectral Classification and Properties of the OVz Stars in the Galactic O Star Spectroscopic Survey (GOSSS). Astronomical Journal 152, 2, DOI: 10.3847/0004-6256/152/2/31
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 lambda 4471, He II lambda 4542, and He II lambda 4686 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.