论文标题
凉爽金属污染的白色矮人中的镁丰度
Magnesium abundances in cool metal-polluted white dwarfs
论文作者
论文摘要
岩石材料的积聚负责大量白矮星的大气中存在沉重的元素。这些对象代表了推断外部活动的批量组成的独特机会。这种化学表征需要使用详细的气氛模型来确定白矮人的光谱中的元素丰度。在这项工作中，我们使用最先进的模型氛围代码来重新分析金属污染的白矮人的首次大型调查，为多个元素发现了很多元素。我们表明，改进的模型构成物理学导致系统上比以前的分析更高的Mg丰度。我们发现平均log mg/ca数量丰度比为1.5。该值显着高于软骨的参考丰度，因为当前的扩散模型预计，对于我们样品毫克的凉爽氦气 - 大气中的白矮星，应比Ca更长的大气中。这有助于解决最近确定的MG耗竭问题，与其行星系统的预期组成相比，据报道白矮人积聚的行星缺乏MG缺陷。
The accretion of rocky material is responsible for the presence of heavy elements in the atmospheres of a large fraction of white dwarf stars. Those objects represent a unique opportunity to infer the bulk composition of exoplanetesimals. This chemical characterization requires the use of detailed atmosphere models to determine the elemental abundances at the photospheres of white dwarfs. In this work, we use a state-of-the-art model atmosphere code to reanalyse the first large survey of metal-polluted white dwarfs for which abundances are found for multiple elements. We show that the improved constitutive physics of our models lead to systematically higher Mg abundances than previous analyses. We find an average log Mg/Ca number abundance ratio of 1.5. This value is significantly above the reference abundance for chondrites, which is expected as current diffusion models predict that for the cool helium-atmosphere white dwarfs of our sample Mg should remain in the atmosphere longer than Ca. This helps resolve a recently identified Mg depletion problem, where the planetesimals accreted by white dwarfs were reported to be Mg-deficient compared to the expected composition of their planetary systems.
