论文标题
TC充足的M星：低质量星的鸭嘴兽进化
Tc-rich M stars: platypuses of low-mass star evolution
论文作者
论文摘要
The technetium-rich (Tc-rich) M stars reported in the literature (Little-Marenin & Little (1979); Uttenthaler et al. (2013)) are puzzling objects since no isotope of technetium has a half-life longer than a few million years, and 99Tc, the longest-lived isotope along the s-process path, is expected to be detected only in thermally-pulsing stars enriched with other s-process元素（如锆）。由于渐近巨型分支（AGB）上的每个热脉冲在同一时间挖出，因此还应富集碳。但是，这些富含TC的物体被归类为M星，这意味着它们既没有明显的锆增强（否则它们将被标记为S型恒星），也没有任何大碳过多（在这种情况下是碳星）。在这里，我们介绍了富含TC的M型星的第一个详细的化学分析，即她。我们首先确认了TC线的检测，然后分析其碳和S过程丰度，并得出有关其进化状态的结论。理解这些TC富含TC的M恒星是限制第三次挖掘的阈值光度的重要步骤，以及在AGB上的第一个热脉冲中，第三次挖掘的阈值亮度和S过程弹出的组成。
The technetium-rich (Tc-rich) M stars reported in the literature (Little-Marenin & Little (1979); Uttenthaler et al. (2013)) are puzzling objects since no isotope of technetium has a half-life longer than a few million years, and 99Tc, the longest-lived isotope along the s-process path, is expected to be detected only in thermally-pulsing stars enriched with other s-process elements (like zirconium). Carbon should also be enriched, since it is dredged up at the same time, after each thermal pulse on the asymptotic giant branch (AGB). However, these Tc-enriched objects are classified as M stars, meaning that they neither have any significant zirconium enhancement (otherwise they would be tagged as S-type stars) nor any large carbon overabundance (in which case they would be carbon stars). Here we present the first detailed chemical analysis of a Tc-rich M-type star, namely S Her. We first confirm the detection of the Tc lines, and then analyze its carbon and s-process abundances, and draw conclusions on its evolutionary status. Understanding these Tc-rich M stars is an important step to constrain the threshold luminosity for the first occurrence of the third dredge-up and the composition of s-process ejecta during the very first thermal pulses on the AGB.
