High resolution and seeing-free spectroscopic observations of a decaying sunspot were done with the Solar Optical Telescope aboard Hinode satellite. We report the magnetic structure and Doppler velocity fields around umbral dots (UDs), based on the Milne-Eddington inversion of the two iron absorption lines at 6302A.The histograms of magnetic field strength (B), inclination angle (i), and Doppler velocity (v) of UDs showed a center-to-limb variation. Observed at the disk center, UDs had (i) slightly smaller field strength (AB = —17 Gauss) and (ii) relative blue shifts (△v =28 m s~(-1)) compared to their surroundings. When the sunspot approached to the limb, UDs and their surroundings showed almost no difference in the magnetic and Doppler values. This center-to-limb variation can be understood by the formation height difference in a cusp-shaped magnetized atmosphere around UDs, due to the weakly magnetized hot gas intrusion. In addition, some UDs showed oscillatory light curves with multiple peaks around 10 min, which may indicate the presence of the oscillatory convection.
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机译：腐朽的太阳黑子的高分辨率和无视光谱观测是用诸如Hinode卫星的太阳能光学望远镜完成的。我们根据6302A的两种铁吸收线的Milne-Eddington反演报告磁性结构和多普勒速度场（UDS）周围的磁性结构和多普勒速度场。磁场强度（b），倾斜角度（i）和多普勒的直方图UDS的速度（v）显示了中心到肢体变化。在盘中观察，UDS（i）与周围环境相比，UDS（i）稍微较小的场强（ab = -17高斯）和（ii）相对蓝色偏移（△V= 28 m s〜（-1））。当过度飞行到肢体时，UDS及其周围环境在磁性和多普勒值中几乎没有差异。由于弱磁化的热气体侵入，因此可以通过在UDS周围的CUSP形磁化气氛中的形成高度差来理解该中心到肢体变化。另外，一些UDS显示出振荡光曲线，其多个峰值约为10分钟，这可以指示振荡对流的存在。
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