标题： α-Cir 的光谱学 -- II. H-α 线的双峰和等值宽度 显示英文标题

标题： Spectroscopy of the roAp star Alpha-Cir -- II. The bisector and equivalent-width of the H-alpha line

摘要： 我们展示了从双地点观测中使用中等色散光谱仪获得的快速脉动Ap（roAp）星Alpha-Cir的H-alpha线的分界线测量结果。 主脉动模式的速度振幅和相位在H-alpha线中的高度不同而显著变化，包括线的核心和翼部之间的相位反转。 这支持了论文I中提出的关于恒星大气中径向脉动节点的理论。 与金属线混合部分影响了H-alpha分界线结果，但可能不足以解释相位反转。 我们还检测到了脉动期间线的等值宽度的变化，并测量了波长在H-alpha区域内的振荡信号。 显示英文摘要

摘要： We present bisector measurements of the H-alpha line of the rapidly oscillating Ap (roAp) star, Alpha-Cir, obtained from dual-site observations with medium-dispersion spectrographs. The velocity amplitude and phase of the principal pulsation mode vary significantly, depending on the height in the H-alpha line, including a phase reversal between the core and the wings of the line. This supports the theory, suggested in Paper I, of a radial pulsational node in the atmosphere of the star. Blending with metal lines partially affects the H-alpha bisector results but probably not enough to explain the phase reversal. We have also detected changes in the equivalent-width of the line during the pulsation, and measured the oscillatory signal as a function of wavelength across the H-alpha region.