arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1005.2489astro-ph.GAphysics.chem-ph
收藏

银河系中心区域的星际HOCN

Interstellar HOCN in the Galactic center region

S. Bruenken, A. Belloche, S. Martin, L. Verheyen, K. M. Menten

摘要:

目标。我们的目标是确认银河系中心云中氰酸(HOCN)的星际探测。以前仅在Sgr B2(OH)中暂时检测到。方法.我们对Sgr B2(N)和(M)的3毫米范围的热芯进行了一次完整的线测量,并辅之以IRAM 30米望远镜在2毫米波段的选定频率上进行的额外观测,以及对Sgr B2云复合体中2和3毫米波段的四个额外位置进行的额外观测。光谱调查进行了分析,在当地的化学平衡近似(LTE)通过建模的所有识别的分子同时发射。这使我们能够区分HOCN的弱特征和在Sgr B2(N)和(M)中观察到的丰富线光谱。线更稳定(1.1 eV)异构体异氰酸,HNCO,在这些来源中,以及那些HOCN和HNCO对其他位置,在LTE近似进行了分析。结果在银河系中心的一个静止分子云中检测到HOCN的四次跃迁,decl.)距离热核源Sgr B2(M)(20“,100”),证实了其先前的初步星际探测。在Sgr B2复合体中,检测到多达四个朝向其他五个位置的跃迁,包括热核Sgr B2(M)、(S)和(N)。对于扩展气体组分,HOCN相对于HNCO的丰度比相当恒定,约为0.3 - 0.8%,表明这些异构体的共同形成过程。

英文摘要:

Aims. Our aim is to confirm the interstellar detection of cyanic acid, HOCN, in the Galactic center clouds. It has previously been tentatively detected only in Sgr B2(OH). Methods. We used a complete line survey of the hot cores Sgr B2(N) and (M) in the 3 mm range, complemented by additional observations carried out with the IRAM 30 m telescope at selected frequencies in the 2 mm band and towards four additional positions in the Sgr B2 cloud complex in the 2 and 3 mm bands. The spectral survey was analysed in the local thermodynamical equilibrium approximation (LTE) by modeling the emission of all identified molecules simultaneously. This allowed us to distinguish weak features of HOCN from the rich line spectrum observed in Sgr B2(N) and (M). Lines of the more stable (by 1.1 eV) isomer isocyanic acid, HNCO, in these sources, as well as those of HOCN and HNCO towards the other positions, were analysed in the LTE approximation as well. Results. Four transitions of HOCN were detected in a quiescent molecular cloud in the Galactic center at a position offset in (R.A., decl.) by (20'',100'') from the hot core source Sgr B2(M), confirming its previous tentative interstellar detection. Up to four transitions were detected toward five other positions in the Sgr B2 complex, including the hot cores Sgr B2(M), (S), and (N). A fairly constant abundance ratio of ~ 0.3 - 0.8 % for HOCN relative to HNCO was derived for the extended gas components, suggesting a common formation process of these isomers.

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。

↑