来自多波长月球掩星的毕宿五光球不对称的证据
Evidence of asymmetries in the Aldebaran photosphere from multi-wavelength lunar occultations
摘要：
我们已经记录了三个月掩星的毕宿五（AlfTau）在不同的望远镜和使用各种带通，从紫外到远红。使用模型依赖和模型独立的方法对数据进行了分析。推导出的均匀光盘角直径值已被转换为边缘变暗的值，使用模型大气关系，并发现在广泛的协议之间，并与以前的文献值。边缘变暗的直径平均约为20.3毫弧秒。然而，我们已经发现迹象表明毕宿五的光球亮度轮廓可能不是对称的，这一发现已经被其他作者报道过了。在我们亮度剖面的采样尺度上，在1到2毫角秒之间，均匀和边缘变暗的圆盘模型可能不是一个很好的描述。在我们测量的137天的时间跨度内，不对称性似乎随波长而不同。表面斑点似乎是观测结果与模型之间差异的一个可能解释。
英文摘要：
We have recorded three lunar occultations of Aldebaran (AlfTau) at different telescopes and using various band-passes, from the ultraviolet to the far red. The data have been analyzed using both model-dependent and model-independent methods. The derived uniform-disc angular diameter values have been converted to limb-darkened values using model atmosphere relations, and are found in broad agreement among themselves and with previous literature values. The limb-darkened diameter is about 20.3 milliarcseconds on average . However, we have found indications that the photospheric brightness profile of Aldebaran may have not been symmetric, a finding already reported by other authors for this and for similar late-type stars. At the sampling scale of our brightness profile, between one and two milliarcsecond, the uniform and limb-darkened disc models may not be a good description for Aldebaran. The asymmetries appear to differ with wavelength and over the 137 days time span of our measurements. Surface spots appear as a likely explanation for the differences between observations and the models.
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