HD 94509的困惑光谱
The Puzzling Spectrum of HD 94509
摘要：
HD 94509的光谱特征非常不寻常，为Be和壳星的动物园增添了一个极端。壳层在光谱中占主导地位，显示出中A到早期F光谱类型的典型谱线，而光球氢线翼和氦线则表明存在晚期/中期B型中心恒星。许多金属吸收线具有宽的翼，但逐渐变窄的芯。它们不能被Voigt轮廓拟合。我们的目标是描述和说明这颗恒星不寻常的光谱特征，并进行粗略的计算，以估计壳层的物理条件和丰度。此外，中央星的特点。我们假设壳的平均条件。电子密度的估计是由英格利斯-泰勒公式。激发温度和列密度的Fe I和Fe II来自生长曲线。中性H柱密度由高Paschen成员估算。的柱密度进行了比较与光电离代码多云的计算。采用非LTE频谱合成来约束中心星的大气参数。总体化学丰度接近太阳能。几种元素的主导离子的柱密度，以及激发温度和平均电子密度很好地占了一个简单的模型。包括电离度在内的几个特征还没有得到很好的描述。HD 94509是一颗Be星，有稳定的壳层，接近末龄主序星。壳的动态状态和形状不寻常但对称的线轮廓需要单独研究。
英文摘要：
The spectral features of HD 94509 are highly unusual, adding an extreme to the zoo of Be and shell stars. The shell dominates the spectrum, showing lines typical for spectral types mid-A to early-F, while the presence of a late/mid B-type central star is indicated by photospheric hydrogen line wings and helium lines. Numerous metallic absorption lines have broad wings but taper to narrow cores. They cannot be fit by Voigt profiles. We aim to describe and illustrate unusual spectral features of this star, and make rough calculations to estimate physical conditions and abundances in the shell. Furthermore, the central star is characterized. We assume mean conditions for the shell. An electron density estimate is made from the Inglis-Teller formula. Excitation temperatures and column densities for Fe I and Fe II are derived from curves of growth. The neutral H column density is estimated from high Paschen members. The column densities are compared with calculations made with the photoionization code Cloudy. Atmospheric parameters of the central star are constrained employing non-LTE spectrum synthesis. Overall chemical abundances are close to solar. Column densities of the dominant ions of several elements, as well as excitation temperatures and the mean electron density are well accounted for by a simple model. Several features, including the degree of ionization, are less well described. HD 94509 is a Be star with a stable shell, close to the terminal-age main sequence. The dynamical state of the shell and the unusually shaped, but symmetric line profiles, require a separate study.
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