发表机构
The University of Tokyo; National Astronomical Observatory of Japan; National Institute for Fusion Science; The Graduate University for Advanced Studies, SOKENDAI（东京大学; 日本国立天文台; 核聚变科学研究所; 综合研究大学院大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用Hinode卫星数据分析了太阳临边附近Fe I 630.15 nm谱线，发现颗粒对流导致朝向临边的红移增加，且颗粒谱线形成区域比颗粒间区域更厚。
AI 中文摘要
光球层谱线的多普勒速度和二等分线表现出显著的从日面中心到临边的变化。这种变化一直被认为是由具有波纹状表面的颗粒对流的投影角度引起的。本研究旨在展示直到临边的谱线位移，并探究这些位移是如何由颗粒对流引起的。我们利用Hinode卫星上的太阳光学望远镜（SOT）的偏振光谱仪（SP）获得的极区观测数据集，对非常接近临边的颗粒进行了空间分辨，分析了Fe I 630.15 nm吸收线。我们还分析了在临边上方1角秒内观测到的Fe I 630.15 nm发射线。本研究揭示了以下几点：1）空间平均的谱线显示，朝向临边的红移增加，然后变得恒定，最后几乎为零；2）被分类为明亮且非磁区的颗粒的多普勒速度显示朝向临边的红移增加；3）颗粒的二等分线变化大于颗粒间区域的变化；4）发射线显示出小的蓝移。这些结果表明，朝向临边的红移增加是由颗粒红移的增加引起的。由于二等分线反映了沿视线方向的大气速度，我们的观测可以被解释为表明颗粒中的谱线形成区域在几何上比颗粒间区域更厚。
英文摘要
The Doppler velocity and bisector of photospheric lines show significant center-to-limb variation. This variation has been considered to be caused by the projection angle of the granular convection which has a corrugated surface. This study aimed to show the spectral line shifts up to limb and investigate how these shifts are caused by granular convection. We analyzed the Fe I 630.15 nm absorption line by spatially resolving the granulation very close to the limb using datasets of polar observations obtained with the Spectro-polarimeter (SP) of the Solar Optical Telescope (SOT) onboard Hinode. We also analyzed the Fe I 630.15 nm emission line, which was observed within 1" above the limb. This study revealed the following: 1) the spatially averaged spectral lines showed an increase in redshift toward the limb, then became constant, and finally became nearly zero, 2) the Doppler velocities of granules, which were classified as bright and non-magnetic regions, showed as increase in redshifts toward the limb, 3) the bisector of granules changed more than that of the intergranules, and 4) the emission lines showed small blueshifts. These results indicate that the increase in redshift toward the limb is caused by the increase in the redshift of granules. Because the bisector reflects the atmospheric velocity along the line-of-sight, our observations can be interpreted as suggesting that the line-forming region in granules is geometrically thicker than that in intergranules.
Comments19 pages, 11 figures, accepted for publication in Solar Physics
