Early-type stars observed in the ESO UVES Paranal Observatory Project - I. Interstellar Na I UV, Ti II and Ca II K observations
Early-type stars observed in the ESO UVES Paranal Observatory Project - I. Interstellar Na I UV, Ti II and Ca II K observations
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ESO UVES Paranal 天文台项目观测到的早期型恒星 - I. 星际 Na I UV、Ti II 和 Ca II K 观测
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
S. Bagnulo
中科院分区：
文献类型：
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作者：
I. Hunter;J. Smoker;F. Keenan;C. Ledoux;E. Jehin;R. Cabanac;C. Melo;S. Bagnulo
本文分析了银河系盘内74条视向线上O型和B型恒星的Na I（λ air = 3302.37和3302.98 A）、Ti II（λ air = 3383.76 A）和Ca II K（λair = 3933.66 A）星际吸收特征。这些数据是从紫外线和可见中阶梯光谱仪帕拉纳尔天文台项目获得的，光谱分辨率为3.75 km s-1，Na I、Ti II和Ca II观测的每像素平均信噪比分别为260、300和430。除了Ti II的一条视线和Ca II的所有视线外，其他所有视线都检测到了星际特征。研究了这三种物质的柱密度与距离、相对于银道面的高度、H I柱密度、相对于太阳丰度的红化和亏损的关系。我们还研究了使用Na I柱密度作为H I的指标的准确性。在一般情况下，我们发现类似的强相关性为钛和钙，和较弱的相关性钠。我们的研究结果证实了一般认为，钛和钙发生在同一地区的星际介质（ISM），也是钛II/钙II的比例是恒定的所有参数。因此，我们得出结论，钛和钙的吸收特性基本上是恒定的一般ISM条件下的银河系光盘。
We present an analysis of interstellar Na I (λair = 3302.37 and 3302.98 A), Ti II (λair = 3383.76 A) and Ca II K( λair = 3933.66 A) absorption features for 74 sightlines towards O- and B-type stars in the Galactic disc. The data were obtained from the Ultraviolet and Visual Echelle Spectrograph Paranal Observatory Project, at a spectral resolution of 3.75 km s −1 and with mean signal-to-noise ratios per pixel of 260, 300 and 430 for the Na I ,T iII and Ca II observations, respectively. Interstellar features were detected in all but one of the Ti II sightlines and all of the Ca II sightlines. The dependence of the column density of these three species with distance, height relative to the Galactic plane, H I column density, reddening and depletion relative to the solar abundance has been investigated. We also examine the accuracy of using the Na I column density as an indicator of that for H I. In general, we find similar strong correlations for both Ti and Ca, and weaker correlations for Na. Our results confirm the general belief that Ti and Ca occur in the same regions of the interstellar medium (ISM) and also that the Ti II/Ca II ratio is constant over all parameters. We hence conclude that the absorption properties of Ti and Ca are essentially constant under the general ISM conditions of the Galactic disc.