Wavelet analysis of stellar differential rotation - III. The Sun in white light
Wavelet analysis of stellar differential rotation - III. The Sun in white light
复制标题
恒星差分旋转的小波分析 - III。
DOI：
10.1051/0004-6361:20021758
复制
发表时间：
2003
影响因子：
6.5
通讯作者：
A. Hempelmann
中科院分区：
文献类型：
--
作者：
A. Hempelmann
像开普勒这样的未来太空项目将提供大量高精度的恒星光曲线。本文描述了利用这些数据对缓慢自转恒星的自转甚至差自转的可观测性进行的检验。研究了两个已发表的太阳总辐照度测量的光曲线：1978年至1993年的Nimbus-7地球辐射预算(ERB)观测和1980至1989年的活动腔辐射计辐射监测器I(ACRIM I)测量。光曲线分析表明，在时间尺度上的振荡与太阳自转相当，但具有复杂的模式。傅立叶分析和时频小波分析都不能得出太阳活动周期较活跃阶段的真实自转周期。在太阳活动极小期，真正的自转周期只占很短的一段时间。根据这项研究，即使是太空诞生的宽带光度法也可能成为研究旋转速度与太阳一样慢的恒星的恒星蝴蝶图的不合适工具。然而，本系列的论文I和II表明，色球示踪剂如Lyman、Mg II h+k和CaII H+K是执行这一任务的合适工具。
Future space projects like KEPLER will deliver a vast quantity of high precision light curves of stars. This paper describes a test concerning the observability of rotation and even dierential rotation of slowly rotating stars from such data. Two published light curves of solar total irradiance measures are investigated: the Nimbus-7 Earth Radiation Budget (ERB) observations between 1978 and 1993 and the Active Cavity Radiometer Irradiance Monitor I (ACRIM I) measurements between 1980 and 1989. Light curve analysis show that oscillations on time-scales comparable to solar rotation but of a complex pattern are visible. Neither Fourier analysis nor time-frequency Wavelet analysis yield the true rotation period during the more active phases of the solar cycle. The true rotation period dominates only for a short time during solar minimum. In the light of this study even space-born broad band photometry may turn out an inappropriate instrument to study stellar butterfly diagrams of stars rotating as slow as the Sun. However, it was shown in Papers I and II of this series that chromospheric tracers like Lyman, Mg II h+k and CaII H+K are appropriate instruments to perform this task.