标题： SX Phoenicis变量的线性非绝热性质 显示英文标题

标题： Linear nonadiabatic properties of SX Phoenicis variables

摘要： 我们提出了一种详细的线性非绝热脉动情景，用于银河系球状星团（GGCs）和本地集团（LG）矮星系中的脉动蓝离散星（BSs）/凤凰座SX（SX Phe）。 模型序列是通过采用广泛的输入参数构建的，并适当覆盖了这些天体预期脉动不稳定的HR图区域。 当前计算以及Gilliland等人已提出的更多金属丰富的模型表明，SX Phe的脉动特性部分受到金属含量的影响。 我们的计算还表明，长期周期变化似乎是一个很好的可观测量，用于识别较冷的SX Phe变星的脉动模式。 讨论了脉动特性对氦包层含量的依赖性，我们发现氦增丰模型的长期周期变化大约是典型模型的两倍。 根据这一证据，我们建议可以可靠地采用SX Phe的脉动特性来限制蓝离散星的演化历史，并进而确定触发其形成的物理机制。 显示英文摘要

摘要： We present a detailed linear, nonadiabatic pulsational scenario for oscillating Blue Stragglers (BSs)/SX Phoenicis (SX Phe) in Galactic Globular Clusters (GGCs) and in Local Group (LG) dwarf galaxies. The sequences of models were constructed by adopting a wide range of input parameters and properly cover the region of the HR diagram in which these objects are expected to be pulsationally unstable. Current calculations together with more metal-rich models already presented by Gilliland et al. suggest that the pulsation properties of SX Phe are partially affected by metal content. Our calculations also suggest that the secular period change seems to be a good observable to identify the pulsation mode of cooler SX Phe variables. The dependence of pulsation properties on the helium envelope content is discussed and we find that the secular period change for He-enhanced models is approximately a factor of two larger than for canonical ones. According to this evidence we suggest that the pulsation properties of SX Phe can be soundly adopted to constrain the evolutionary history of BSs, and in turn to single out the physical mechanisms which trigger their formation.