标题： HD 164270 (WC9)物理性质和风特性从紫外到中红外的研究及其与BD+30 3639 ([WC9])的比较 显示英文标题

标题： An Ultraviolet to Mid-Infrared Study of the Physical and Wind Properties of HD 164270 (WC9) and Comparison to BD+30 3639 ([WC9])

摘要： 我们展示了HD164270（WC9，WR103）的新Spitzer IRS观测结果。 定量分析了HD164270的UV、光学、近红外和中红外光谱，考虑了线状吸收和风团聚效应，揭示了T* ~ 48kK，log L/L_sun ~ 4.9，体积填充因子为f ~ 0.1时的dM/dt ~ 1e-5 M_sun/yr。 我们的模型预测，在外层恒星风中He部分再结合，这意味着WC9恒星最近由无线电推导出的质量损失率被低估了。 通过光学诊断，我们得到C/He ~ 0.2和O/He ~ 0.01（按数量计算）。 观察到[NeII] 12.8微米和[SIII] 18.7微米的中红外精细结构线，而[NeIII]和[SIV]缺失。 由此得到Ne/He ~ Ne^+/He = 2.2e-3（按数量计算），比太阳值高7倍（根据Asplund等人最近的推导），以及S/He ~ S^2+/He = 5.1e-5（按数量计算）。 通过对其他WC亚型类似结果的比较，我们得出结论，WC9恒星与早期亚型一样化学上先进。 我们探讨了为什么晚期WC恒星仅在高金属丰度环境中被观测到。 此外，我们将HD164270的UV/光学/中红外光谱形态与行星状星云中心星BD+30 3639（[WC9]）进行了比较。 它们的UV和光学特征非常相似，因此我们的定量比较证实了Smith & Aller最初提出的恒星温度、风密度和化学成分的相似性，尽管它们有着完全不同的演化历史，目前HD164270的质量是BD+30 3639的十倍。 在中红外波长上，BD+30 3639年轻稠密星云中的尘埃完全支配了它的外观，与HD164270形成对比。 显示英文摘要

摘要： We present new Spitzer IRS observations of HD164270 (WC9, WR103). A quantitative analysis of the UV, optical, near- and mid-IR spectrum of HD164270 is presented, allowing for line blanketing and wind clumping, revealing T* ~ 48kK, log L/L_sun ~ 4.9, dM/dt ~ 1e-5 M_sun/yr for a volume filling factor of f \~ 0.1. Our models predict that He is partially recombined in the outer stellar wind, such that recent radio-derived mass-loss rates of WC9 stars have been underestimated. We obtain C/He ~ 0.2 and O/He ~ 0.01 by number from optical diagnostics. Mid-IR fine structure lines of [NeII] 12.8 and [SIII] 18.7micron are observed, with [NeIII] and [SIV] absent. From these we obtain Ne/He ~ Ne^+/He = 2.2e-3 by number, 7 times higher than the Solar value (as recently derived by Asplund et al.), and S/He ~ S^2+/He = 5.1e-5 by number. From a comparison with similar results for other WC subtypes we conclude that WC9 stars are as chemically advanced as earlier subtypes. We consider why late WC stars are exclusively observed in high metallicity environments. In addition, we compare the UV/optical/mid-IR spectroscopic morphology of HD164270 with the Planetary Nebula central star BD+30 3639 ([WC9]). Their UV and optical signatures are remarkably similar, such that our quantitative comparisons confirm similarities in stellar temperature, wind densities and chemistry first proposed by Smith & Aller, in spite of completely different evolutionary histories, with HD164270 presently a factor of ten more massive than BD+30 3639. At mid-IR wavelengths, the dust from the dense young, nebula of BD+30 3639 completely dominates its appearance, in contrast with HD164270.