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arXiv 1403.2183astro-ph.SRphysics.atom-ph
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恒星实验室II。新的Zn IV和Zn V振子强度及其在热白矮星G191-B2B和RE0503-289中的验证

Stellar laboratories II. New Zn IV and Zn V oscillator strengths and their validation in the hot white dwarfs G191-B2B and RE0503-289

T. Rauch, K. Werner, P. Quinet, J. W. Kruk

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53 pages, 8 figures
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摘要：

对于热星的高分辨率和高信噪比光谱的光谱分析，最先进的非局部热力学平衡（NLTE）模型大气是强制性的。这在很大程度上取决于用于计算的原子数据的可靠性。在最近对DA型白矮星G191-B2 B的紫外光谱分析中，新发现了21条Zn IV谱线。由于缺乏锌IV的数据，过渡概率的等电子锗VI适应的第一，粗略的测定光球锌丰度。我们对Zn IV和Zn V振子强度进行了新的计算，以详细考虑它们在NLTE恒星大气模型中的辐射和碰撞束缚跃迁，用于分析G191-B2B和RE 0503 -289的高分辨率和高S/N UV观测中显示的Zn IV - V光谱。在G191-B2B的紫外光谱中，我们鉴定出31条Zn IV和16条Zn V谱线。其中大多数是首次在任何恒星中发现的。在log Zn = -5.52 +/-0.2（质量分数，约为太阳的1.7倍）时，我们可以很好地再现几乎所有的光谱。特别是，Zn IV / Zn V电离平衡，这是一个非常敏感的指标的有效温度，很好地再现与先前确定的Teff = 60000 +/- 2000和log g = 7.60 +/- 0.05。在RE 0503 -289的光谱中，我们首次识别了128条Zn V线，并确定了log Zn = -3.57 +/-0.2（155倍太阳）。对原子数据的可靠测量和计算是恒星大气建模的先决条件。用我们新计算的振子强度很好地再现了两颗白矮星（G191-B2B和RE 0503 -289）紫外光谱中Zn IV和Zn V的谱线轮廓。这使我们能够精确地确定这两颗恒星的光球Zn丰度。

英文摘要：

For the spectral analysis of high-resolution and high-signal-to-noise spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model-atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. In a recent analysis of the ultraviolet (UV) spectrum of the DA-type white dwarf G191-B2B, 21 Zn IV lines were newly identified. Because of the lack of Zn IV data, transition probabilities of the isoelectronic Ge VI were adapted for a first, coarse determination of the photospheric Zn abundance. We performed new calculations of Zn IV and Zn V oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of the Zn IV - V spectrum exhibited in high-resolution and high-S/N UV observations of G191-B2B and RE0503-289. In the UV spectrum of G191-B2B, we identify 31 Zn IV and 16 Zn V lines. Most of these are identified for the first time in any star. We can reproduce well almost all of them at log Zn = -5.52 +/- 0.2 (mass fraction, about 1.7 times solar). In particular, the Zn IV / Zn V ionization equilibrium, which is a very sensitive indicator for the effective temperature, is well reproduced with the previously determined Teff = 60000 +/- 2000 and log g = 7.60 +/- 0.05. In the spectrum of RE0503-289, we identified 128 Zn V lines for the first time and determined log Zn = -3.57 +/- 0.2 (155 times solar). Reliable measurements and calculations of atomic data are a pre-requisite for stellar-atmosphere modeling. Observed Zn IV and Zn V line profiles in two white dwarf (G191-B2B and RE0503-289) ultraviolet spectra were well reproduced with our newly calculated oscillator strengths. This allowed us to determine the photospheric Zn abundance of these two stars precisely.

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