The solar differential rotation in the 18th century
The solar differential rotation in the 18th century
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18世纪的太阳差动自转
DOI：
10.1051/0004-6361/201219266
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发表时间：
2012
影响因子：
6.5
通讯作者：
H. Froehlich
中科院分区：
文献类型：
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作者：
R. Arlt;H. Froehlich
约翰·施达切尔（Johann Staudacher）于1749年至1799年绘制的太阳黑子图被用来确定那个时期的太阳微分旋转。这些完整圆盘的图没有任何指向。假设赤道自转周期与今天相同，我们使用贝叶斯估计器获得了图纸的位置角度，相应的日光斑位置，图纸之间的时间偏移量和微分旋转参数δΩ。这些图纸成对分组，并将δΩ的边际分布相乘。我们得到δ Ω=−0.048±0.025 d−1（−2.75◦/d）为整个时期。与现在太阳的价值没有显著差异。我们发现一个（不显著的）迹象表明，在整个观测期内，δΩ从强的微分旋转δΩ≈−0.07 d−1，到弱的微分旋转δΩ≈−0.04 d−1。
The sunspot drawings of Johann Staudacher of 1749–1799 were used to determine the solar differential rotation in that period. These drawings of the full disk lack any indication of their orientation. We used a Bayesian estimator to obtain the position angles of the drawings, the corresponding heliographic spot positions, a time offset between the drawings and the differential rotation parameter δΩ, assuming the equatorial rotation period is the same as today. The drawings are grouped in pairs, and the resulting marginal distributions for δΩ were multiplied. We obtain δ Ω= −0.048 ± 0.025 d −1 (−2.75 ◦ /d) for the entire period. There is no significant difference to the value of the present Sun. We find an (insignificant) indication for a change of δΩ throughout the observing period from strong differential rotation, δΩ ≈− 0.07 d −1 , to weaker differential rotation, δΩ ≈− 0.04 d −1 .