Interstellar Extinction and Elemental Abundances: Individual Sight Lines
Interstellar Extinction and Elemental Abundances: Individual Sight Lines
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DOI：
10.3847/1538-4365/ac2cc3
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发表时间：
2021-11
期刊：
影响因子：
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通讯作者：
W. Zuo;Aigen Li;Gang Zhao
中科院分区：
文献类型：
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作者：
W. Zuo;Aigen Li;Gang Zhao
虽然众所周知，银河星际消光曲线和尘埃形成元素的气相丰度从一条视线到另一条视线都表现出相当大的变化，但大多数尘埃消光建模工作都针对银河平均消光曲线，该曲线是通过对许多不同气体和尘埃特性的云进行平均而获得的。因此，有关尘埃特性与星际环境之间关系的任何细节都会丢失。在这里，我们利用太空望远镜获得的丰富的消光和元素丰度数据，探索大量单独视线的尘埃特性。我们对每条视线观察到的消光曲线进行建模，并推导出需要束缚在灰尘中（即灰尘消耗）的主要灰尘形成元素（即 C、O、Si、Mg 和 Fe）的丰度。然后，我们将衍生的尘埃损耗与观测到的这些元素的气相丰度进行比较，并研究环境对尘埃特性和元素损耗的影响。研究发现，对于大部分视线，星际氧原子完全被气体和尘埃容纳，因此不存在“缺氧”问题。对于消光氢柱密度 A V /N H ≳ 4.8 × 10−22 mag cm2 H−1 的视线，即使星际 C/H、Si/H、Mg/H 和 Fe/H 丰度被假定为由银河化学物质增强的原太阳丰度，也缺乏 C、Si、Mg 和 Fe 元素来制造尘埃来解释观测到的消光。 进化。
While it is well recognized that both the Galactic interstellar extinction curves and the gas-phase abundances of dust-forming elements exhibit considerable variations from one sight line to another, as yet most of the dust extinction modeling efforts have been directed to the Galactic average extinction curve, which is obtained by averaging over many clouds of different gas and dust properties. Therefore, any details concerning the relationship between the dust properties and the interstellar environments are lost. Here we utilize the wealth of extinction and elemental abundance data obtained by space telescopes and explore the dust properties of a large number of individual sight lines. We model the observed extinction curve of each sight line and derive the abundances of the major dust-forming elements (i.e., C, O, Si, Mg, and Fe) required to be tied up in dust (i.e., dust depletion). We then confront the derived dust depletions with the observed gas-phase abundances of these elements and investigate the environmental effects on the dust properties and elemental depletions. It is found that for the majority of the sight lines the interstellar oxygen atoms are fully accommodated by gas and dust and therefore there does not appear to be a “missing oxygen” problem. For those sight lines with an extinction-to-hydrogen column density A V /N H ≳ 4.8 × 10−22 mag cm2 H−1 there are shortages of C, Si, Mg, and Fe elements for making dust to account for the observed extinction, even if the interstellar C/H, Si/H, Mg/H, and Fe/H abundances are assumed to be protosolar abundances augmented by Galactic chemical evolution.