Ap-stars GO And、84 UMa和$κ$ Psc的基本参数
Fundamental parameters of the Ap-stars GO And, 84 UMa, and $κ$ Psc
摘要：
本工作的目的是利用光谱技术测定三颗Ap星GO And（HD 4778）、$κ$ Psc（HD 220825）和84 UMa（HD 120198）的基本参数。通过分析这些恒星，我们完成了样本的Ap星的基本参数已另外通过干涉测量。这使得通过直接和间接方法得出的结果能够进行交叉比较。对于所有调查的恒星，我们确定的基本参数和衍生的化学丰度是典型的AP星。丰度的主要特点是逐渐增加的重元素大气丰度从一个数量级的铁峰值元素到非常显着过量的3-4 dex的稀土元素相对于太阳值。唯一的例外是Ba，其丰度接近太阳丰度。在HD 120198和HD 220825的大气中也有明显的He缺乏，而HD 4778的He丰度接近太阳丰度。我们没有发现显着的Fe和Cr分层。利用这些丰度，我们为每颗恒星构建了自洽的大气模型。表面化学不均匀性对导出的基本参数的影响在有效温度下不超过+/-100 K，这在Ap星类似自洽分析的误差范围内。最后，我们比较了光谱推导出的有效温度，半径和光度的13个14 Ap星在基准样品的干涉测量结果。虽然半径和光度在两次测定的误差范围内，但对于温度为$T_{eff} >$ 9000 K的恒星，光谱有效温度高于干涉测量温度。观察到的氢线轮廓有利于光谱导出的温度。
英文摘要：
The aim of this work is to determine fundamental parameters of three Ap stars, GO And (HD 4778), $κ$ Psc (HD 220825), and 84 UMa (HD 120198), using spectroscopic techniques. By analysing these stars, we complete the sample of Ap stars for which fundamental parameters have additionally been derived by means of interferometry. This enables a cross-comparison of results derived by direct and indirect methods. For all investigated stars, we determined fundamental parameters and derived chemical abundances that are typical for Ap stars. The abundances are mainly characterised by a gradual increase of heavy element atmospheric abundances from an order of magnitude for iron peak elements up to very significant excesses of 3-4 dex of the rare-earth elements relative to the solar values. The only exception is Ba, whose abundance is close to the solar abundance. There is also a significant He deficiency in the atmospheres of HD 120198 and HD 220825, whereas the He abundance in HD 4778 is close to the solar abundance. We do not find significant Fe and Cr stratification. Using these abundances, we constructed self-consistent atmospheric models for each star. The effect of the surface chemical inhomogeneity on the derived fundamental parameters did not exceed +/-100 K in effective temperature, which lies within the range of errors in similar self-consistent analyses of Ap stars. Finally, we compared spectroscopically derived effective temperatures, radii, and luminosity for 13 out of 14 Ap stars in a benchmark sample with the interferometric results. While radii and luminosity agree within the quoted errors of both determinations, the spectroscopic effective temperatures are higher than the interferometric temperatures for stars with temperatures $T_{eff} >$ 9000 K. The observed hydrogen line profiles favour the spectroscopically derived temperatures.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
