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标题：Oxygen budget in low-mass protostars: the NGC 1333-IRAS4A R1 shock observed in [O i] at 63 μm with SOFIA-GREAT
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作者：L. E. Kristensen ; L. E. Kristensen ; A. Gusdorf 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2017
卷号：601
页码：1-5
DOI：10.1051/0004-6361/201630310
语种：English
出版社：EDP Sciences
摘要：In molecular outflows from forming low-mass protostars, most oxygen is expected to be locked up in water. However, Herschel observations have shown that typically an order of magnitude or more of the oxygen is still unaccounted for. To test if the oxygen is instead in atomic form, SOFIA-GREAT observed the R1 position of the bright molecular outflow from NGC 1333-IRAS4A. The [O i] 63 μm line is detected and spectrally resolved. From an intensity peak at +15 km s-1, the intensity decreases until +50 km s-1. The profile is similar to that of high-velocity (HV) H2O and CO 16–15, the latter observed simultaneously with [O i]. A radiative transfer analysis suggests that ~15% of the oxygen is in atomic form toward this shock position. The CO abundance is inferred to be ~10-4 by a similar analysis, suggesting that this is the dominant oxygen carrier in the HV component. These results demonstrate that a large portion of the observed [O i] emission is part of the outflow. Further observations are required to verify whether this is a general trend.
关键词：stars: formation;ISM: molecules;ISM: jets and outflows;ISM: individual objects: NGC 1333-IRAS4A R1