星际重水的邻位-对位比
太阳与恒星天体物理
2015-05-19 v1
摘要
尽管银河系中元素氘的丰度很低，但在低质量恒星形成区域，特别是Class 0原恒星IRAS 16293-2422的环境中，已发现增强的分子D/H比。CHESS（恒星形成区域的化学赫歇尔巡天）重点计划旨在研究星际介质的分子复杂性。HIFI仪器的高灵敏度和高光谱分辨率提供了独特的机会，可以观测到地面无法观测的邻位-D2O分子的基态1,1,1 - 0,0,0跃迁，并确定邻位-对位D2O比。我们在IRAS 16293-2422方向探测到了邻位-D2O分子在607.35 GHz处的基态跃迁。该谱线呈吸收特征，线不透明度为0.62 ± 0.11（1σ）。根据先前地面观测到的对位-D2O分子在316.80 GHz处的基态1,1,0 - 1,0,1跃迁（呈吸收特征），我们估计其线不透明度为0.26 ± 0.05（1σ）。我们表明，观测到的吸收是由原恒星包层中的冷气体引起的。利用这些新观测，我们首次估计出邻位-对位D2O比低于2.6（3σ不确定度水平），而热平衡值为2:1。
引用
@article{arxiv.1007.4410,
title = {Ortho-to-para ratio of interstellar heavy water},
author = {C. Vastel and C. Ceccarelli and E. Caux and A. Coutens and J. Cernicharo and S. Bottinelli and K. Demyk and A. Faure and L. Wiesenfeld and Y. Scribano and A. Bacmann and P. Hily-Blant and S. Maret and A. Walters and E. A. Bergin and G. A. Blake and A. Castets and N. Crimier and C. Dominik and P. Encrenaz and M. Gérin and P. Hennebelle and C. Kahane and A. Klotz and G. Melnick and L. Pagani and B. Parise and P. Schilke and V. Wakelam and A. Baudry and T. Bell and M. Benedettini and A. Boogert and S. Cabrit and P. Caselli and C. Codella and C. Comito and E. Falgarone and A. Fuente and P. F. Goldsmith and F. Helmich and T. Henning and E. Herbst and T. Jacq and M. Kama and W. Langer and B. Lefloch and D. Lis and S. Lord and A. Lorenzani and D. Neufeld and B. Nisini and S. Pacheco and J. Pearson and T. Phillips and M. Salez and P. Saraceno and K. Schuster and X. Tielens and F. van der Tak and M. H. D. van der Wiel and S. Viti and F. Wyrowski and H. Yorke and P. Cais and J. M. Krieg and M. Olberg and L. Ravera},
journal= {arXiv preprint arXiv:1007.4410},
year = {2015}
}
备注
5 pages, 5 figures, accepted the A&A HIFI Special Issue as a letter