AI 中文总结
研究利用CHARA阵列对31颗恒星在H和K波段进行干涉临边昏暗测量，用四种定律拟合数据并与五个恒星大气网格预测比较，测量角直径精度约0.2 - 0.3%，结果为恒星大气模型提供近红外基准。
AI 中文摘要
临边昏暗，即恒星强度从圆盘中心到边缘的降低，编码了恒星大气的温度结构和不透明度。直接对这种中心到边缘变化进行空间分辨测量仍然很少，尤其是在近红外波段。我们展示了用CHARA阵列同时在H和K波段观测的31颗恒星的干涉临边昏暗测量结果。样本涵盖光谱类型F - M和光度等级IV - I。目标在H波段得到很好分辨，大多数目标在K波段也能分辨。这种覆盖范围限制了联合H + K拟合中与临边昏暗相关的可见度曲率。我们用四种解析临边昏暗定律拟合组合的H + K平方可见度，并将所得系数与来自五个恒星大气网格（Kurucz、MPS1、MPS2、Stagger和球形SATLAS，报告的系数基于罗斯兰半径约定）的带通匹配预测进行比较，这些网格涵盖一维平面平行、三维辐射 - 流体动力学和球形低重力模型。相关的临边昏暗角直径测量的中值形式精度约为0.2 - 0.3%。CHARA结果显示在较长波长以及有效温度增加时临边昏暗预期会减弱。与大气网格最明显的差异在于波长依赖性：CHARA样本中幂律系数从H到K的中值分数下降约为39%，而模型预测仅约为17 - 22%。相对于MPS2比较，经验系数在H波段高约21%，在K波段低约5%。这些结果提供了多波段干涉临边昏暗作为恒星大气模型的近红外基准。
英文摘要
Limb darkening, the decrease in stellar intensity from the disk center to the limb, encodes the temperature structure and opacity of stellar atmospheres. Direct spatially resolved measurements of this center-to-limb variation remain scarce, especially in the near-infrared. We present interferometric limb-darkening measurements for 31 stars observed simultaneously in the $H$ and $K$ bands with the CHARA Array. The sample spans spectral types F--M and luminosity classes IV--I. The targets are well resolved in $H$ and, for most targets, also in $K$. This coverage constrains the visibility curvature associated with limb darkening in joint $H+K$ fits. We fit the combined $H{+}K$ squared visibilities with four analytic limb-darkening laws and compare the resulting coefficients with bandpass-matched predictions from five stellar-atmosphere grids (Kurucz, MPS1, MPS2, Stagger, and spherical SATLAS, with reported coefficients placed on the Rosseland-radius convention) spanning one-dimensional plane-parallel, three-dimensional radiation--hydrodynamic, and spherical low-gravity models. The associated limb-darkened angular diameters are measured with median formal precisions of $\simeq 0.2$--0.3\%. The CHARA results show expected weaker limb darkening at longer wavelengths and also with increasing $T_{\rm eff}$. The clearest discrepancy with the atmosphere grids is in the wavelength dependence: the median fractional decrease in the power-law coefficient from $H$ to $K$ is $\simeq 39\%$ in the CHARA sample, compared with only $\simeq 17$--$22\%$ with model predictions. Relative to the MPS2 comparison, the empirical coefficients are higher by $\simeq 21\%$ in $H$ and lower by $\simeq 5\%$ in $K$. These results provide multi-band interferometric limb darkening as a near-infrared benchmark for stellar-atmosphere models.
CommentsAccepted for publication in The Astronomical Journal; 16 figures, 6 tables and 28 pages
