Heavy-metal hot subdwarfs (sdB and sdO) represent a small group of stars with unusually high concentrations of trans-iron elements in their atmospheres, having abundances ~ 10000 times solar. One example is LS IV-14$^{\circ}$ 116, where a number of heavy-metal absorption lines of Sr II, Y III and Zr IV have been observed in the optical band 4000 - 5000 A. We use a fully relativistic Dirac atomic R-Matrix (DARC) to calculate photoionization cross sections of Sr$^{0}$, Y$^{+}$ and Zr$^{2+}$ from their ground state to the twentieth excited level. We use the cross sections and the oscillator strengths to simulate the spectrum of a hot subdwarf. We obtain complete sets of photoionization cross sections for the three ions under study. We use these data to calculate the opacity of the stellar atmospheres of hot subdwarf stars, and show that for overabundances observed in some heavy-metal subdwarves, photo-excitation from zirconium, in particular, does contribute some back warming in the model.

中文翻译：

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重金属热亚矮星的不透明度建模：Sr0、Y+ 和 Zr2 + 的光电离

重金属热亚矮星（sdB 和 sdO）代表一小组在其大气中具有异常高浓度反式铁元素的恒星，其丰度约为太阳的 10000 倍。一个例子是 LS IV-14$^{\circ}$116，其中在 4000 - 5000 A 光带中观察到了许多 Sr II、Y III 和 Zr IV 的重金属吸收谱线。相对论狄拉克原子 R 矩阵 (DARC) 计算 Sr$^{0}$、Y$^{+}$ 和 Zr$^{2+}$ 从基态到第 20 个激发能级的光电离截面。我们使用横截面和振荡器强度来模拟热亚矮星的光谱。我们获得了所研究的三种离子的全套光电离截面。我们使用这些数据来计算热亚矮星的恒星大气的不透明度，