Observations of Water Vapor Outflow from NML Cygnus
Observations of Water Vapor Outflow from NML Cygnus
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NML 天鹅座水蒸气流出的观测
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
M. Harwit
中科院分区：
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作者：
V. Zubko;Di Li;T. Lim;H. Feuchtgruber;M. Harwit
我们报告了基于红外空间天文台和亚毫米波天文卫星收集的数据对NML天鹅座远红外和亚毫米波水蒸气发射的新观测结果。我们将NML Cyg的辐射与先前发表的VY CMa和W Hya的辐射进行比较，试图建立最近提出的演化恒星流出模型的有效性。获得的数据支持了ivezizic和Elitzur的论点，即演化恒星的大气遵循一套标度定律，其中流出物的光学深度是最重要的标度参数，它既影响辐射传输，也影响流出物的动力学。具体来说，我们提供了比较NML Cyg， VY CMa和W Hya的水蒸气排放的观测结果，并发现，在我们数据质量允许的范围内，结果与Zubko和Elitzur开发的模型基本一致。利用这个模型，我们根据在这些富氧巨星的大气中观测到的尘埃不透明度、光谱线通量和水蒸气流出速度，得出了质量损失。对于vycma和NML Cyg，我们也得到了恒星质量的估计。
We report new observations of the far-infrared and submillimeter water vapor emission of NML Cygnus based on data gathered with the Infrared Space Observatory and the Submillimeter Wave Astronomy Satellite. We compare the emission from NML Cyg to that previously published for VY CMa and W Hya in an attempt to establish the validity of recently proposed models for the outflow from evolved stars. The data obtained support the contention by Ivezić & Elitzur that the atmospheres of evolved stars obey a set of scaling laws in which the optical depth of the outflow is the single most significant scaling parameter, affecting both the radiative transfer and the dynamics of the outflow. Specifically, we provide observations comparing the water vapor emission from NML Cyg, VY CMa, and W Hya and find, to the extent permitted by the quality of our data, that the results are in reasonable agreement with a model developed by Zubko & Elitzur. Using this model we derive a mass loss based on the dust opacities, spectral line fluxes, and outflow velocities of water vapor observed in the atmospheres of these oxygen-rich giants. For VY CMa and NML Cyg, we also obtain an estimate of the stellar mass.