渐近巨星支（AGB）上的脉动：全局视角
Pulsations along the Asymptotic Giant Branch (AGB): a global view
AI总结：
本文针对AGB恒星脉动研究仅局限于米拉变星的缺陷，分析大样本半规则与不规则变星，揭示两类不同演化路径的AGB恒星及其后代特征，探讨其富氧到富碳的转变及质量等影响因素。
AI中文摘要：
在前三篇文章中，我们研究了米拉变星的光变曲线与其恒星性质之间的关系。分析仅限于可见光观测密度和质量较高的恒星样本，这使得光变曲线的简单参数化得以定义。研究揭示了恒星沿AGB的演化与光脉冲宽度、上升分支与正弦波的偏差等参数之间存在明确关系。然而，研究仅限于米拉变星，这一限制被发现是阻碍得出完整图像的主要缺陷。本文通过回顾大样本半规则变星和不规则变星，克服了这一不足。本文提供了两类具有不同后代的恒星的证据：第一类恒星进入AGB时已在脉动，振幅达到1个星等的量级；它持续冷却和膨胀，同时脉动振幅和周期增大，光脉冲宽度减小；其后代主要是前三篇文章中研究的部分米拉变星。第二类恒星进入AGB时尚未出现显著脉动；其部分后代可能在不进入热脉动分支且不经历强烈的第三次 dredge-up（TDU）事件的情况下离开AGB；其他后代则可能成为前三篇文章中研究的、具有更宽光脉冲的米拉变星。本文研究并描述了两类恒星从富氧到富碳的可能转变。本文还就当前最先进知识背景下对这些结果的解释提出了看法。第一类恒星的初始质量往往大于第二类恒星，而对流包层的性质细节似乎也在决定恒星所属的家族中发挥作用。
英文摘要：
In three preceding articles, we studied the relation between the light curves of Mira variables and their stellar properties. The analysis was restricted to a sample of stars offering high density and quality of observations in the visible, allowing for the definition of simple parameterizations of the light curves. Clear relations were revealed between the evolution of the stars along the AGB and parameters such as the width of the light pulse or the deviation of its ascending branch from a sine wave. However, the restriction to Mira variables was found to be a major drawback preventing a complete picture to be drawn. The present article overcomes this deficiency by reviewing a large sample of semi-regular and irregular variables. It gives evidence for two families of stars having different progenies. The first family enters the AGB already pulsating with amplitudes at the scale of one unit of magnitude. It keeps cooling down and expanding, while pulsating with increasing amplitudes and periods and decreasing width of the light pulse; its progeny is dominated by some of the Mira variables studied in the three preceding articles. The second family enters the AGB before displaying significant pulsations; some of its progeny may leave the AGB without entering the Thermally Pulsing Branch and experiencing strong TDU events; others may instead become Mira variables studied in the three preceding articles and pulsating with a broader light pulse. The possible transition of both families from oxygen-rich to carbon-rich is studied and described. Comments on the interpretation of these results in the context of current state-of-the-art knowledge are presented. While the stars of the first family tend to have larger initial masses than the stars of the second family, details of the properties of the convective envelope seem also to play a role in defining which families a star belongs to.
