利用绝对定标碘盒光谱学测量太阳较差自转
Measurement of Solar Differential Rotation by Absolutely Calibrated Iodine-Cell Spectroscopy
AI总结：
针对以往碘盒光谱法测量太阳较差自转时未充分考虑日面谱线临边变化的问题，改用理论光谱拟合获取绝对日心径向速度并结合最小二乘法分析，得到了与文献相符的更精确自转参数和引力红移值。
摘要：
碘盒技术因在精确测定多普勒速度位移方面的高效性而闻名，作者曾基于全日面光谱观测将其应用于测量太阳较差自转（Takeda and Ueno, Sol. Phys. 270, 447, 2011）。然而，该研究中采用的数据处理过程（简单类比恒星情况）并不一定合适，因为没有适当考虑与分辨日面相关的具体特征（即谱线强度的临边昏暗变化）。因此，基于相同数据但采用理论光谱拟合重新研究了该问题，该方法能以一致的方式得出绝对日心径向速度（v_obs），如太阳引力红移研究所示（Takeda and Ueno, Sol. Phys. 281, 551, 2012）。同样，这次没有将每个日面点的 v_obs 转换为 omega（角速度）（这在中央子午线附近误差较大），而是对包含多个点 v_obs 值的数据集应用最小二乘分析来推导 omega。新分析得出 omega（度/天）= 13.92（+/- 0.03）-1.69（+/- 0.34）(sin psi)^2 -2.37（+/- 0.62）(sin psi)^4（psi：日面纬度），以及 675 m/s 的引力红移，与以往文献结果相符。此外，还考察了观测点在日面上的分布如何影响结果，发现视情况而定，自转参数可能存在显著误差。
英文摘要：
The iodine-cell technique, which is known to be efficient in precisely establishing Doppler velocity shifts, was once applied by the author to measuring the solar differential rotation based on full-disk spectroscopic observations (Takeda and Ueno, Sol. Phys. 270, 447, 2011). However, the data reduction procedure (in simple analogy with the stellar case) adopted therein was not necessarily adequate, because specific characteristic involved with the disk-resolved Sun (i.e., center-limb variation of line strengths) was not properly taken into consideration. Therefore, this problem is revisited based on the same data but with an application to theoretical spectrum fitting, which can yield absolute heliocentric radial velocities (v_obs) in a consistent manner as shown in the study of solar gravitational redshift (Takeda and Ueno, Sol. Phys. 281, 551, 2012). Likewise, instead of converting v_obs into omega (angular velocity) at each disk point, which suffers considerable errors especially near the central meridian, omega was derived this time by applying the least squares analysis to a dataset comprising v_obs values at many points. This new analysis resulted in omega (deg/day) = 13.92 (+/- 0.03) -1.69(+/- 0.34)(sin psi)^2 -2.37(+/- 0.62) (sin psi)^4 (psi: the heliographic latitude) along with the gravitational redshift of 675 m/s, which are favorably compared with previous publications. In addition, how the distribution of observing points on the disk affects the result is also examined, which reveals that rotation parameters may suffer appreciable errors depending on cases.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
