边缘变暗的大角星;用IOTA/IONIC干涉仪成像
The limb-darkened Arcturus; Imaging with the IOTA/IONIC interferometer
摘要：
本文对大角星进行了H波段干涉测量，大角星是一颗经常用作空间和光谱定标器的恒星。利用IOTA-3干涉仪对大角星进行了光谱干涉观测（R~35）。大气模型和处方被拟合到数据中，以得出光球的亮度分布。还使用两种软件算法获得图像重建：Wisard和Mira。一个消色差的幂律被证明是一个很好的模型的亮度分布，与一个来自大气模型模拟使用我们的Marcs模型的一个兼容的临边变暗。导出Rosseland直径为21.05 ± 0.21，对应于有效温度T_eff=4295 ± 26 K。在闭合阶段没有检测到伴星，亮度比的上限为8 e-4。在距光球层如此距离处的动态范围被确定为1.5e-4（1 sigma rms）。上限为1.7e-3也是光球层上亮度不对称的水平。
英文摘要：
This paper is an H band interferometric examination of Arcturus, a star frequently used as a spatial and spectral calibrator. Using the IOTA 3 telescope interferometer, we performed spectro-interferometric observation (R~35) of Arcturus. Atmospheric models and prescriptions were fitted to the data to derive the brightness distribution of the photosphere. Image reconstruction was also obtained using two software algorithms: Wisard and Mira. An achromatic power law proved to be a good model of the brightness distribution, with a limb darkening compatible with the one derived from atmospheric model simulations using our Marcs model. A Rosseland diameter of 21.05+/-0.21 was derived, corresponding to an effective temperature of T_eff=4295+/-26 K. No companion was detected from the closure phases, with an upper limit on the brightness ratio of 8e-4 at 1AU. Dynamic range at such distance from the photosphere was established at 1.5e-4 (1sigma rms). An upper limit of 1.7e-3 was also derived for the level of brightness asymmetries present on the photosphere.
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