标题： 一些关于roAp星的最新结果 显示英文标题

标题： Some recent results for the roAp stars

摘要： 三个主题被讨论：1) 对快速振荡Ap星的测光观测显示，脉动振幅随波长从蓝端到红端显著下降。理论推导和建模表明，这是由于脉动模式的垂直波长相对于大气尺度高度较短；事实上，这表明我们在可观测大气中看到了一个脉动节点。径向速度观测和理论计算现在支持这一观点。对其他CP星研究的含义是，这可以提供独立于传统光谱分析的大气结构观测约束。 2) roAp星的光度可以通过星震学确定。最近将这种星震学光度与HIPPARCOS光度进行比较的结果如图所示。这表明roAp星的温度和/或半径比以前模型所使用的要低，或者这些恒星的磁场改变了频率间隔。 3) 讨论了我们对某些roAp星脉动频率长期监测的最新结果。脉动腔存在明显的周期性变化，因此这些恒星的声速和/或声速传播时间（半径）也存在变化。这可能表明存在磁周期，其水平目前的磁测量无法检测到，尽管这种想法尚无理论支持。 显示英文摘要

摘要： Three topics are discussed: 1) Photometric observations of the rapidly oscillating Ap stars have shown that the pulsation amplitude drops dramatically as a function of wavelength from the blue to the red. A theoretical derivation, plus modelling, indicates that this is because the vertical wavelength of the pulsation mode is short compared to the scale height of the atmosphere; in fact, it indicates that we are seeing a pulsation node in the observable atmosphere. Radial velocity observations, and theoretical calculations now support this. The implication for other research on CP stars is that this can provide observational constraints on the atmospheric structure independent of traditional spectral analysis. 2) Luminosities of roAp stars can be determined from asteroseismology. A recent comparison of such asteroseismic luminosities with HIPPARCOS luminosities is shown. This suggests that roAp stars have lower temperatures and/or smaller radii than previous models have used, or that the magnetic fields in these stars alter the frequency separations. 3) The latest results of our long-term monitoring of the pulsation frequencies in certain roAp stars are discussed. There is a clear cyclic variability to the pulsation cavity, hence the sound speed and/or sound travel time (radius) of these stars. This might be indicative of magnetic cycles at a level that magnetic measurements cannot currently detect, although there is no theoretical support for such an idea.