One-dimensional (1D) model atmospheres are still the most c ommonly used tool for the determination of stellar chemical composition. Convection in the m odel is usually treated by mixing-length theory (MLT). The mixing-length parameter α is generally calibrated from the Sun and applied to all other sta s. The metal-poor giant, HD 122563, is an important benchmark s tar to test stellar atmosphere and interior physics. We investigate the influence of the convection mixi ng-length parameter α on the determination of chemical abundances of Na, Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Co Ni, Sr, Y, Zr and Ba in the case of HD 122563, taking advantage of a high resolution and high sig nal-to-noise ratio HARPS spectrum. The abundance discrepancies ∆[X/H] that occur due toα variation rarely exceed 0.05 dex and most are less than 0.03 dex. We calculate the discrepancy ∆[X/H] using a line-by-line differential analysis. The abundance discrepancies do not have direct relation with either lin strength or the excitation potential. For 1D stellar atmospheric analysis of HD 122563, the accuracy of a bundance determination does not strongly depend on the choice of mixing-length parameter α (causing average discrepancies of < 0.03dex), while the uncertainties in the effective temperature and surface gra vity play a more important role.

中文翻译：

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对流混合长度参数 α 对贫金属巨星 HD 122563 化学丰度的影响

一维（1D）模式大气仍然是最常用的确定恒星化学成分的工具。模型中的对流通常用混合长度理论 (MLT) 处理。混合长度参数 α 通常从太阳校准并应用于所有其他恒星。贫金属巨星HD 122563是测试恒星大气和内部物理的重要基准星。我们研究了对流混合长度参数 α 对测定 Na、Mg、Al、Si、Ca、Sc、Ti、Cr、Mn、Co Ni、Sr、Y、Zr 和 Ba 的化学丰度的影响。 HD 122563 的情况，利用高分辨率和高信噪比 HARPS 频谱。由α变异引起的丰度差异Δ[X/H]很少超过0.05 dex，大多数小于0.03 dex。我们使用逐行差异分析计算差异Δ[X/H]。丰度差异与 lin 强度或激发电位没有直接关系。对于 HD 122563 的一维恒星大气分析，能量流确定的准确性并不强烈依赖于混合长度参数 α 的选择（导致平均差异 < 0.03dex），而有效温度和表面重力的不确定性一个更重要的角色。