WATER FRACTIONS IN EXTRASOLAR PLANETESIMALS
WATER FRACTIONS IN EXTRASOLAR PLANETESIMALS
复制标题
太阳系外行星中的水分数
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
Siyi Xu
中科院分区：
文献类型：
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作者：
M. Jura;Siyi Xu
为了利用外部污染的白色矮星来研究太阳系外小行星的水分，我们从文献中收集了一个样本，我们估计超过60%的DB白色矮星的温度超过13，000 K，亮度超过3 × 10−3 L，距离太阳80 pc。当把所有的恒星放在一起考虑时，我们发现重原子的总质量吸积率超过氢的1000倍以上。如果是这样的话，这一太阳系外小行星的子群被视为一个整体，几乎没有水，至少比最原始的陨石CI陨石干燥20倍。此外，虽然一个明显的“过剩”的氧气在一个单一的DB可以被解释为证据，吸积材料起源于一个富含水的母体，我们表明，至少在某些情况下，可以有足够的不确定性的吸积率的时间历史，这样的论点可能是模棱两可的。不管与解释从单个对象的结果相关的困难，我们的分析人口的污染DBs提供了间接的观测支持的理论观点，雪线是重要的岩石星子形成的磁盘。
With the goal of using externally polluted white dwarfs to investigate the water fractions of extrasolar planetesimals, we assemble from the literature a sample that we estimate to be more than 60% complete of DB white dwarfs warmer than 13,000 K, more luminous than 3 × 10−3 L☉, and within 80 pc of the Sun. When considering all the stars together, we find that the summed mass accretion rate of heavy atoms exceeds that of hydrogen by over a factor of 1000. If so, this sub-population of extrasolar asteroids treated as an ensemble has little water and is at least a factor of 20 drier than CI chondrites, the most primitive meteorites. Furthermore, while an apparent “excess” of oxygen in a single DB can be interpreted as evidence that the accreted material originated in a water-rich parent body, we show that at least in some cases, there can be sufficient uncertainties in the time history of the accretion rate that such an argument may be ambiguous. Regardless of the difficulty associated with interpreting the results from an individual object, our analysis of the population of polluted DBs provides indirect observational support for the theoretical view that a snow line is important in disks where rocky planetesimals form.