标题： 活动双星的光球丰度 I HD 113816（IS Vir）和HD 119285（V851 Cen）的详细分析 显示英文标题

标题： The photospheric abundances of active binaries I Detailed analysis of HD 113816 (IS Vir) and HD 119285 (V851 Cen)

摘要： 对两个X射线活动双星RS CVn型恒星HD 113816（IS Vir）和HD 119285（V851 Cen）的高分辨率光学光谱进行了分析，并确定了它们的Na、Mg、Al、Si、Ca、Sc、Ti、Co和Ni含量。 使用三种不同的LTE方法对IS Vir和V851 Cen进行了分析。 在第一种方法中，利用测量的等效宽度和Kurucz LTE模型大气作为MOOG软件包的输入来推导丰度。输入的大气参数和丰度通过迭代修改，直到(i) Fe I丰度与激发势或等效宽度没有趋势，(ii) Fe I和Fe II平均丰度相同，以及(iii) Fe和Alpha元素的平均丰度与输入值一致。 第二种方法采用了类似的方法，但依靠B-V和V-I颜色指数来确定温度。 第三种方法依赖于拟合6162 Å Ca I线翼轮廓来推导表面重力。 这些方法的可靠性在单线RS CVn星的背景下进行了研究。 结果显示，V-I测光指数比B-V指数给出了更广泛的样本中显著较低的有效温度估计。 所有其他方法的结果彼此一致。 对IS Vir和V851 Cen的分析结果表明，它们的主星均为接近太阳金属丰度的巨星。 利用第一种方法得到的参数分别为：Teff = 4720 K, log g = 2.65, [Fe/H] = +0.04 和 Teff = 4700 K, log g = 3.0, [Fe/H] = -0.13。 对于V851 Cen，推导出的铁含量显著高于文献中的先前测定值。 这两颗恒星相对于太阳混合物表现出几种元素的相对过量（例如Ca）。 显示英文摘要

摘要： The high-resolution optical spectra of the two X-ray active binaries RS CVn stars HD 113816 (IS Vir) and HD 119285 (V851 Cen) are analysed and their Na, Mg, Al, Si, Ca, Sc, Ti, Co and Ni contents determined. The analysis of IS Vir and V851 Cen is performed with three different LTE methods. In the first one, abundances are derived using measured equivalent widths and Kurucz LTE model atmospheres as input for the MOOG software package. The input atmospheric parameters and abundances are iteratively modified until (i) the Fe I abundances exhibit no trend with excitation potential or equivalent width, (ii) Fe I and Fe II average abundances are the same and (iii) Fe and Alpha elements average abundances are consistent with the input values. The second method follows a similar approach, but relies on the B-V and V-I colour indices to determine the temperature. The third method relies on fitting the 6162 A Ca I line wing profiles to derive the surface gravity. The reliability of these methods is investigated in the context of single line RS CVn stars. It is shown that the V-I photometric index gives, on a broader sample of stars, significantly cooler estimates of the effective temperature than the B-V index. All other approaches give results in good agreement with each other. The analysis of IS Vir and V851 Cen results in both cases in their primaries being giant stars of near-solar metallicity. Their parameters as derived with the first method are respectively Teff = 4720 K, log g = 2.65, [Fe/H] = +0.04 and Teff = 4700 K, log g = 3.0 and [Fe/H] = -0.13. In the case of V851 Cen the derived iron content is significantly higher than a previous determination in the literature. Both stars exhibit relative overabundances of several elements (e.g. Ca) with respect to the solar mix.