确认了星周磷化氢
Confirmation of circumstellar phosphine
摘要：
磷化氢（PH 3）是几年前在碳星包层IRC+10216和CRL 2688中通过观测J=1-0旋转跃迁产生的266.9 GHz发射线而初步确定的。我们报告的J=2-1的旋转跃迁的检测在IRC+10216使用Herschel上的HIFI仪器，这明确地证实了PH 3的识别。辐射转移计算表明，红外泵浦到激发振动态在IRC+10216包层中PH 3的激发中发挥着重要作用，并且观察到的谱线与在恒星和100 R* 之间的任何地方形成的磷化氢一致。恒星，相对于H2的丰度为1 e-8。PH 3的检测挑战化学模型，没有一个提供令人满意的形成方案。虽然PH 3仅占IRC+10216中总有效磷的2%，但它与HCP一起，HCP是内部拱星层中磷的主要气相载体之一，这表明它也可能是其他天文环境中重要的磷物种。这是第一次在太阳系外明确探测到PH 3，也是更好地了解太空中磷化学的又一步。
英文摘要：
Phosphine (PH3) was tentatively identified a few years ago in the carbon star envelopes IRC+10216 and CRL2688 from observations of an emission line at 266.9 GHz attributable to the J=1-0 rotational transition. We report the detection of the J=2-1 rotational transition of PH3 in IRC+10216 using the HIFI instrument on board Herschel, which definitively confirms the identification of PH3. Radiative transfer calculations indicate that infrared pumping to excited vibrational states plays an important role in the excitation of PH3 in the envelope of IRC+10216, and that the observed lines are consistent with phosphine being formed anywhere between the star and 100 R* from the star, with an abundance of 1e-8 relative to H2. The detection of PH3 challenges chemical models, none of which offers a satisfactory formation scenario. Although PH3 locks just 2 % of the total available phosphorus in IRC+10216, it is together with HCP, one of the major gas phase carriers of phosphorus in the inner circumstellar layers, suggesting that it could be also an important phosphorus species in other astronomical environments. This is the first unambiguous detection of PH3 outside the solar system, and a further step towards a better understanding of the chemistry of phosphorus in space.
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