arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1202.3992astro-ph.GA
收藏

原行星盘中氘增强的多途径证据

Evidence for Multiple Pathways to Deuterium Enhancements in Protoplanetary Disks

Karin I. Oberg, Chunhua Qi, David J. Wilner, Michiel R. Hogerheijde

备注：
accepted for publication in ApJ
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

氘代分子在原行星盘中的分布取决于分子的形成途径。我们使用ALMA科学验证期间用~3”合成光束获得的TW Hya周围盘的空间分辨DCN发射的观测结果，以及来自亚毫米阵列的可比DCO+观测结果，来研究这些物质径向分布的差异，从而研究它们形成化学的差异。与DCO+相反，DCO+显示了随半径增加的柱密度，DCN更适合于中心峰值的模型。我们推断，DCN形成在一个较小的半径，因此在更高的温度比DCO+。这与化学网络模型预测的在T<30 K下从H2 D+形成DCO+和在更高温度下从涉及CH 2D+的额外途径形成DCN一致。我们估计DCN/HCN丰度比约为0.017，类似于DCO+/HCO+丰度比。在这个原行星盘的温度范围内，氘分馏似乎是有效的。这些结果表明，在解释太阳系天体中观察到的氘分数范围时要谨慎，因为应该考虑到多种形成途径。

英文摘要：

The distributions of deuterated molecules in protoplanetary disks are expected to depend on the molecular formation pathways. We use observations of spatially resolved DCN emission from the disk around TW Hya, acquired during ALMA Science verification with a ~3" synthesized beam, together with comparable DCO+ observations from the Submillimeter Array, to investigate differences in the radial distributions of these species and hence differences in their formation chemistry. In contrast to DCO+, which shows an increasing column density with radius, DCN is better fit by a model that is centrally peaked. We infer that DCN forms at a smaller radii and thus at higher temperatures than DCO+. This is consistent with chemical network model predictions of DCO+ formation from H2D+ at T<30 K and DCN formation from additional pathways involving CH2D+ at higher temperatures. We estimate a DCN/HCN abundance ratio of ~0.017, similar to the DCO+/HCO+ abundance ratio. Deuterium fractionation appears to be efficient at a range of temperatures in this protoplanetary disk. These results suggest caution in interpreting the range of deuterium fractions observed in Solar System bodies, as multiple formation pathways should be taken into account.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

↑