Asymmetry in Velocity and Intensity Helioseismic Spectra: A Solution to a Long-standing Puzzle
Asymmetry in Velocity and Intensity Helioseismic Spectra: A Solution to a Long-standing Puzzle
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速度和强度日震频谱的不对称性：解决长期难题
DOI：
10.1086/311219
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Jesper Schou
中科院分区：
文献类型：
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作者：
R. Nigam;A. Kosovichev;Philip Scherrer;Jesper Schou
我们给出了一个解释的速度和强度振荡功率谱的太阳声模式线的不对称性的相反的意义，从而解决了半个十年之久的难题的杜瓦尔和同事。在将太阳和日光层观测站上的迈克尔逊多普勒成像仪获得的中等角度l的速度和强度振荡数据与理论功率谱进行比较后得出了该解。我们的结论是，在速度和强度谱的太阳噪声是由两个组成部分：一个是相关的源，负责驱动太阳p-模式，另一个是一个附加的不相关的背景。噪声的相关分量影响线轮廓。强度谱的不对称性被反转，因为相关分量具有足够大的水平，而速度谱的不对称性保持不反转，因为相关分量较小。这也解释了在声学截止频率处和以上的速度和强度之间的高频偏移。当位于光球层下75±50 km深度的超绝热对流区时，由质量项（质量项）和偶极子项（雷诺应力引起的力）组成的复合源可以解释观测到的光谱。
We give an explanation for the opposite sense of asymmetry of the solar acoustic mode lines in velocity and intensity oscillation power spectra, thereby solving the half-decade-old puzzle of Duvall and coworkers. The solution came after comparing the velocity and intensity oscillation data of medium angular degree l obtained from the Michelson Doppler Imager instrument on board the Solar and Heliospheric Observatory with the theoretical power spectra. We conclude that the solar noise in the velocity and intensity spectra is made up of two components: one is correlated to the source that is responsible for driving the solar p-modes, and the other is an additive uncorrelated background. The correlated component of the noise affects the line profiles. The asymmetry of the intensity spectrum is reversed because the correlated component is of a sufficiently large level, while the asymmetry of the velocity spectrum remains unreversed because the correlated component is smaller. This also explains the high-frequency shift between velocity and intensity at and above the acoustic cutoff frequency. A composite source consisting of a monopole term (mass term) and a dipole term (force due to Reynolds stress) is found to explain the observed spectra when it is located in the zone of superadiabatic convection at a depth of 75±50 km below the photosphere.