论文标题
在热极星星中检测氟
Detection of fluorine in hot Extreme Helium Stars
论文作者
论文摘要
本文的主要目的是探索热极星（EHES）中氟的丰度。氟的不足是凉爽的Ehes和R Coronae Borealis（RCB）恒星的特征，并进一步实施了它们的紧密连接。对于热e，基于它们的氟丰度，这种与冷却器的关系尚未探索。我们在本文中介绍了由单个离子化的氟线（F \，{\ sc ii}）确定的氟的第一个丰度估计值，该氟来自光谱的10个热恒星。使用F \，{\ sc ii}线确定氟的丰度，以3505Å\和3850Å为中心的两个窗口中。 10颗恒星中有6颗显示出类似于凉爽的氟的显着增强。两个贫困的热ehs没有氟的特征，对于F的丰度具有明显的高度上限。将这些氟的丰度与这些恒星中观察到的其他元素丰度进行了比较，这些恒星提供了有关这些恒星形成和演变的想法。 C，O和NE氟的趋势表明，在共同的白矮人合并后，大量的氦气燃烧可以解释大部分观察到的丰度。根据观察到的丰度，讨论了白矮人合并模拟的预测。
The main objective of this paper is to explore abundances of fluorine in hot Extreme Helium Stars (EHes). Overabundance of fluorine is a characteristic feature for cool EHes and R Coronae Borealis (RCB) stars and further enforces their close connection. For hot EHes this relationship with the cooler EHes, based on their fluorine abundance is unexplored. We present in this paper the first abundance estimates of fluorine determined from singly ionised fluorine lines (F\,{\sc ii}) for 10 hot EHe stars from optical spectra. Fluorine abundances were determined using the F\,{\sc ii} lines in two windows centered at 3505 Å\ and 3850 Å. Six of the 10 stars show significant enhancement of fluorine similar to the cool EHes. Two carbon-poor hot EHes show no signature of fluorine and have a significant low upper limit for the F abundance. These fluorine abundances are compared with the other elemental abundances observed in these stars which provide an idea about the formation and evolution of these stars. The trends of fluorine with C, O, and Ne show that significant helium burning after a CO-He white dwarf merger can account for a majority of the observed abundances. Predictions from simulations of white dwarf mergers are discussed in light of the observed abundances.
