A cool, magnetic white dwarf accreting planetary debris
A cool, magnetic white dwarf accreting planetary debris
复制标题
一颗冷磁性白矮星正在吸积行星碎片
DOI：
10.1093/mnras/stad3370
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发表时间：
2023
影响因子：
4.8
通讯作者：
Melis, Carl
中科院分区：
文献类型：
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作者：
Vennes, Stéphane;Kawka, Adela;Klein, Beth L.;Zuckerman, B.;Weinberger, Alycia J.;Melis, Carl
我们对冷的、高磁性的、污染的白色矮星2 MASS J 0916 −4215的光谱数据进行了分析。白色矮星的大气主要由氢组成，但镁、钙、钛、铬、铁和锶的许多谱线，以及沿着的Lii、Nai、Ali和Kilines，都在不完整的帕申-巴克区中被发现，最明显的是在Caiilines的情况下。广泛的新的计算的Paschen-Back效应在几个谱线和计算的结果列在表格中的CaiiH&K双重。丰度模式显示大量的锂和锶过剩，这可能被视为类似于地球大陆地壳的行星碎片在星星上堆积的标志，尽管硅的稀缺表明大块地球物质可能被稀释。准确的丰度测量证明敏感的加宽参数的值，由于碰撞中性氢（Hi），特别是在饱和线，如共振线的Cai和Caii。我们发现thatHiif制定的值从文献中可以被高估了10倍，在大多数共振线。
We present an analysis of spectroscopic data of the cool, highly magnetic, and polluted white dwarf 2MASS J0916−4215. The atmosphere of the white dwarf is dominated by hydrogen, but numerous spectral lines of magnesium, calcium, titanium, chromium, iron, and strontium, along with Lii, Nai, Ali, and Kilines, are found in the incomplete Paschen–Back regime, most visibly, in the case of Caiilines. Extensive new calculations of the Paschen–Back effect in several spectral lines are presented and results of the calculations are tabulated for the CaiiH&K doublet. The abundance pattern shows a large lithium and strontium excess, which may be viewed as a signature of planetary debris akin to Earth’s continental crust accreted on to the star, although the scarcity of silicon indicates possible dilution in bulk Earth material. Accurate abundance measurements proved sensitive to the value of the broadening parameter due to collisions with neutral hydrogen (Hi), particularly in saturated lines such as the resonance lines of Caiand Caii. We found thatHiif formulated with values from the literature could be overestimated by a factor of 10 in most resonance lines.