标题： 银河系O星光谱调查（GOSSS）中O Vz星的光谱分类和特性 显示英文标题

标题： Spectral classification and properties of the O Vz stars in the Galactic O-Star Spectroscopic Survey (GOSSS)

摘要： 基于银河系O型星光谱调查（GOSSS），对O Vz恒星进行了详细系统的研究。 目前使用的光谱分类标准被重新讨论，并通过添加基于He I 4471、He II 4542和He II 4686光谱线等值宽度的定量标准，对Vz现象进行了重新校准。 对新采用的光谱分类标准所产生的GOSSS O Vz和O V群体进行了比较分析。 探测了O Vz恒星的位置，显示出最极端的情况集中在最年轻的恒星形成区域。 还研究了在太阳金属丰度环境中Vz光谱异常现象的发生情况，这由fastwind代码预测，确认了在正确解释该现象时考虑多个过程的重要性。 显示英文摘要

摘要： On the basis of the Galactic O-Star Spectroscopic Survey (GOSSS), a detailed systematic investigation of the O Vz stars is presented. 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 4471, He II 4542, and He II 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.