旋转黑子的太阳周时间延迟研究

统计结果显示23周旋转黑子的纬度随时间的变化呈蝴蝶图分布.对23周旋转黑子蝴蝶图和黑子蝴蝶图两翼的4条拟合曲线间的均方差随相位变化进行研究的结果表明:黑子蝴蝶图南北半球之间、旋转黑子蝴蝶图南北半球之间以及在同一半球旋转黑子蝴蝶图和黑子蝴蝶图之间存在着系统的时间延迟.这说明:23周南北半球太阳黑子活动不是同时发生的,南半球和北半球之间存在着系统的时间延迟或提前(相位差),且是南半球滞后于北半球;23周旋转黑子蝴蝶图和黑子蝴蝶图之间存在着相位差,且是旋转黑子蝴蝶图滞后于黑子蝴蝶图,观测滞后值略小于发电机模型预言的理论值.     

Relationship between Rotating Sunspots and Flares

Active Region (AR) NOAA 10486 was a super AR in the declining phase of solar cycle 23. Dominated by the rapidly rotating positive polarity of an extensive δ sunspot, it produced several powerful flare-CMEs. We study the evolution and properties of the rotational motion of the major poles of positive polarities and estimate the accumulated helicity injected by them. We also present two homologous flares that occurred in the immediate periphery of the rotating sunspots. The main results are as follows: i) anticlockwise rotational motions are identified in the main poles of positive polarities in the AR; the fastest of them is about 220° for six days. ii) The helicity injection inferred from such rotational motion during the interval from October 25 to 30 is about − 3.0×10⁴³ Mx², which is comparable that calculated by the local correlation tracking (LCT) method (− 5.2×10⁴³ Mx²) in the whole AR. It is suggested that both methods reveal the essential topological properties of the AR, even if the former includes only the major poles and the fine features of the magnetic field are neglected. iii) It is found that there is a good spatial and temporal correspondence between the onset of two homologous CME-associated flares and the rotational motion of sunspots. This suggests that the rotational motions of sunspots not only relate to the transport of magnetic energy and complexity from the low atmosphere to the corona but may also play a key role in the onset of the homologous flares. Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users.     

Long-term Clock Bias Prediction Based on An ARMA Model

The long-term and reliable prediction of satellite clock bias (SCB) is an important prerequisite for realizing the satellite autonomous navigation and orbit determination. Considering the shortcomings of the quadratic polynomial model (PM) and gray system model (GM) in the long-term prediction of SCB, a new prediction method of SCB based on an ARMA (Auto-Regressive Moving Average) model is proposed to represent the variation characteristics of SCB more accurately. In this paper, a careful precision analysis of the 90-day SCB prediction is made to verify the feasibility and validity of this proposed method by using the IGS (International GNSS Service) clock data. According to the variation characteristics of each satellite clock, the pattern recognition, modeling and prediction of SCB are conducted, and the detailed comparison is made with the other three models at the same time. The results show that adopting the ARMA model can effectively improve the accuracy of long-term SCB prediction.     

A Statistical Analysis of X1- and X2- or Higher-Class Flares during Solar Cycles 21∼23

The X1- and X2- or higher class ?ares in solar cycles 21, 22, and 23 from 1986 to 2008 have been analyzed statistically in this paper. It is found in the statistical study that the number of the X1-class ?ares accounted for 52.71% of total X- and higher class ?ares, while, the number of the X2- and higher class ?ares accounted for 47.29% of total X- and higher class ?ares. No matter whether the X1- and X2- or higher class ?ares, most of them occured in the descending phases of the solar cycles. Moreover, the weaker the intensity of the solar cycle, the higher the ratio of the ?ares occurred in the descending phase of the solar cycle, and the stronger the intensity of solar ?ares, the higher the ratio of the ?ares occurred in the descending phases of the solar cycles. In addition, the phase difference between the peak of the smoothed monthly mean number of sunspots and that of the X-class ?ares has been calculated, which shows that the smoothed monthly mean number of the X1-class ?ares had a very noticeable time advance of 1 month with respect to that of sunspots in the cycles 21 and 22, but there was a time lag of 13 months in the cycle 23, while, for the X2- and higher class ?ares, there was a time lag of 9 months in the cycle 21, but a one-month time advance existed in the cycle 22, and again a time lag of 32 months appeared in the cycle 23.     

Anomalous Variation of VLF Signals in the Total Solar Eclipse of 22nd July 2009

Using the sudden ionospheric disturbance (SID) monitor provided by the Stanford University, the very low frequency (VLF) signals were observed in Nanjing during the total solar eclipse on 22nd July 2009. It is found that the intensity of the VLF signal varied anomalously during the total solar eclipse, exhibiting the effect similar to the sunrise and sunset, and that the intensity of the VLF signal strongly fluctuated, exhibiting the effect similar to thunderbolts. Moreover, the signal intensity enhanced in short periods both before and after the total eclipse. Based on the discussion on the reliability of the observed data and the comparison with the previous observations, it is found that the ionosphere exhibits some variations previous to the total solar eclipse.     

Evolutionary Characteristics of Total Solar Irradiance

The significant periods of total solar irradiance are 35 d and 26 d in the 23rd and 24th solar activity cycles, respectively. It is inferred that the solar quasi-rotation periods are also 35 d and 26 d in the 23rd and 24th solar activity cycles, respectively. The value of total solar irradiance around the 24th solar activity minimum may be close to the value of Maunder minimum. On the timescales from one solar rotation period to several months, sunspots are the main reason to cause the variation of total solar irradiance, but not the unique one, and the variation of total solar irradiance are not correlated with the Mg II index on the timescales from a few days to one solar rotation period.     

日面新生黑子的经度分布

以云南天文台对５２２个太阳自转周的观测资料统计,在可见日面上新生的黑子,各个太阳活动周出现频数不等。从中筛选出面积ＣＹ≥５００的２２８群,以及ＣＹ≥１２００的２９群,它们分别都在经度上呈相对集中性,但又多随时间变化而漂移,在时间分布上无规律性。在可比的太阳第２１和２２活动周内,新生黑子对应的最强烈活动区只有８１２００和９２３９０,另外是８２４９５回转的８２５３３对应在最强烈活区,说明新生大黑子无固定的活动源。     

Sunspots: An overview

Sunspots are the most readily visible manifestations of solar magnetic field concentrations and of their interaction with the Sun's plasma. Although sunspots have been extensively studied for almost 400 years and their magnetic nature has been known since 1908, our understanding of a number of their basic properties is still evolving, with the last decades producing considerable advances. In the present review I outline our current empirical knowledge and physical understanding of these fascinating structures. I concentrate on the internal structure of sunspots, in particular their magnetic and thermal properties and on some of their dynamical aspects. Received 27 September 2002 / Published online 3 March 2003     

Observations of Rotating Sunspots from TRACE

Recent observations from TRACE in the photospheric white-light channel have shown sunspots that rotate up to 200° about their umbral centre over a period of 3–5 days. The corresponding loops in the coronal fan are often seen to twist and can erupt as flares. In an ongoing study, seven cases of rotating sunspots have been identified, two of which can be associated with sigmoid structures appearing in Yohkoh/SXT and six with events seen by GOES. This paper analyzes the rotation rates of the sunspots using TRACE white-light data. Observations from AR 9114 are presented in detail in the main text and a summary of the results for the remaining six sunspots is presented in Appendixes A–F. Discussion of the key results, particularly common features, are presented, as well as possible mechanisms for sunspot rotation. Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1026138413791     

The Processing and Classification for the Spectra of Six Comets

In order to explore the relationship between comets and asteroids, the spectra of six comets, including 78P, C/2009 P1, 49P, C/2010 G2, C/2010 S1, and C/2011 F1, have been observed with the 2.16 m telescope at the Xinglong Observing Station of National Astronomical Observatories. At the same time, the spectra of some sun-like stars are also observed. The IRAF (Image Reduction and Analysis Facility) software is used to process the obtained spectra, and to obtain the relative re?ectance spectra of the six comets. Then, they are compared with the 24 asteroid spectral types of the Bus-DeMeo taxonomy to derive the spectral distances of these comets. According to the order of the calculated spectral distances, the details of the re?ectance spectra, as well as the results of the K-S test, the asteroid spectral types which are most close to the spectra of these comets are ?nally determined.     

Solar-cycle variation of the sound-speed asphericity from GONG and MDI data 1995–2000

We study the variation of the frequency splitting coefficients describing the solar asphericity in both GONG and MDI data, and use these data to investigate temporal sound-speed variations as a function of both depth and latitude during the period 1995–2000 and a little beyond. The temporal variations in even splitting coefficients are found to be correlated to the corresponding component of magnetic flux at the solar surface. We confirm that the sound-speed variations associated with the surface magnetic field are superficial. Temporally averaged results show a significant excess in sound speed around     and latitude of 60°.     

Propagation of the Slow Magnetoacoustic Waves in Coronal Loops Above Sunspots

The observations from the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) have revealed the weak dis- turbances (WDs) propagating in the fan-like coronal loops of the active region (AR 11092) at 171 ?A, 193 ?A, and 211 ?A. These WDs seem to be a common phenomenon in this part of the active region. The disturbances originate from the bright loop foot, and propagate along the loops. The observed propagation speed decreases with the increasing temperature, and varies between 40 km/s and 121 km/s, close to and less than the sound speed in coronal loops. Consid- ering the projection effect and the different angles of the loops with respect to the line of sight, this is exactly what the slow-wave model expects. The wavelet analysis shows that the periods of the WDs observed in different wavebands have no signi?cant difference, the two distinct periods, 3 min and more than 10 min, are all detected in the three EUV wavebands. Not only the coronal loops but also the sunspot region in the chromosphere exhibit intensity oscillations with a period of the order of 3 min. This result suggests that the sunspot oscillations can propagate into the corona through the chromosphere and transition region.     

On the choice of parameters in solar-structure inversion

The observed solar p-mode frequencies provide a powerful diagnostic of the internal structure of the Sun and permit us to test in considerable detail the physics used in the theory of stellar structure. Among the most commonly used techniques for inverting such helioseismic data are two implementations of the optimally localized averages (OLA) method, namely the subtractive optimally localized averages (SOLA) and multiplicative optimally localized averages (MOLA). Both are controlled by a number of parameters, the proper choice of which is very important for a reliable inference of the solar internal structure. Here we make a detailed analysis of the influence of each parameter on the solution and indicate how to arrive at an optimal set of parameters for a given data set.     

On the measurement precision of solar p-mode eigenfrequencies

We make use of 3456 d of observations of the low-ℓ p-mode oscillations of the Sun in order to study the evolution over time of the measurement precision of the radial eigenfrequencies. These data were collected by the ground-based Birmingham Solar-Oscillations Network (BiSON) between 1991 January and 2000 June. When the power spectrum of the complete time series is fitted, the analysis yields frequency uncertainties that are close to those expected from the returned coherence times of the modes. The slightly elevated levels compared with the prediction appear to be consistent with a degradation of the signal-to-noise ratio in the spectrum that is the result of the influence of the window function of the observations (duty cycle 71 per cent). The fractional frequency precision reaches levels of a several parts in 10⁶ for many of the modes. The corresponding errors reported from observations made by the GOLF instrument on board the ESA/NASA SOHO satellite, when extrapolated to the length of the BiSON data set, are shown to be (on average) about ∼25 per cent smaller than their BiSON counterparts owing to the uninterrupted nature of the data from which they were derived.
An analysis of the BiSON data in contiguous segments of different lengths, T , demonstrates that the frequency uncertainties scale as T ^−1/2. This is to be expected in the regime where the coherence (life) times of the modes, τ _{n ℓ}, are smaller than the observing time T (the 'oversampled' regime). We show that mode detections are only now beginning to encroach on the 'undersampled' regime (where   T < τ _{n ℓ})  .     

Relative phase analyses of long-term hemispheric solar flare activity

Wavelet transform methods, including the continuous wavelet transform, cross-wavelet transform and wavelet coherence, have been proposed to investigate the phase synchrony of the monthly mean flare indices in the time interval 1966 January–2007 December in the solar northern and southern hemispheres, respectively. The Schwabe cycle is the only period of statistical significance, and its mean value is 10.7 yr for the monthly mean flare indices in the northern hemisphere but slightly smaller, 10.1 yr, in the southern hemisphere – this should lead to phase asynchrony between the two. Both the cross-wavelet transform and wavelet coherence analyses show asynchronous behaviour with strong phase mixing in the high-frequency components of hemispheric flare activity, and strong synchronous behaviour with coherent phase angles in the low-frequency components, corresponding to the period-scales around the Schwabe cycle. The northern flare activity should lead the southern for the low-frequency components.     

The SHASTA Code Modified by Self-adaptive Mesh and Numerical Experiment of Magnetic Reconnections

SHASTA (Sharp and Smooth Transport Algorithm) is a code with single mesh to solve the 2-dimensional magnetohydrodynamic (MHD) equations. When SHASTA is used to the numerical simulation of magnetic reconnection problem, it is modified to be the code which adopts the method of the selfadaptive mesh. The modified code can carry out refined calculations in diffusion regions. In the process of the self-adaptive calculations with SHASTA, a “plugand-play” strategy is adopted and the original algorithm to solve 2-dimensional MHD partial differential equations is treated as an independent cell. In addition, the hierarchical data structure is used in this modification and parameters in each refined level are described by a 2-dimensional variable array. The regions where the distributions of magnetic field and pressure exhibit steep variations are marked as the refined regions. Then, the distributions of physical quantities and the boundary conditions in the grid points of refined levels are deduced via interpolation method. Finally, the refined calculated results of refined regions are assigned to the previous level of mesh and the existing results are updated. The numerical experiment of magnetic reconnections which adopts refined calculations indicates that compared with the code with single mesh, the resolution of details is improved and the corresponding increment of computing time is related to the selection of parameters in the simulation. The calculation accuracy and effect on instability, which are caused by a part of the self-adaptive code, depend on the boundary settings, push strategy over each single step as well as the interpolation algorithm.     

Detection and temporal coherence of p‐modes below 1.4 mHz

Data collected recently by the helioseismic experiments aboard the SOHO spacecraft have allowed the detection of low degree p‐modes with increasingly lower order n. In particular, the GOLF experiment is currently able to unambiguously identify low degree modes with frequencies as low as 1.3 mHz. The detection of p‐modes with very low frequency (i.e., low n), is difficult due to the low signal‐to‐noise ratio in this spectral region and its contamination by solar signals that are not of acoustic origin. To address this problem without using any theoretical a priory, we propose a methodology that relies only on the inversion of observed values to define a spectral window for the expected locations of these low frequency modes. The application of this method to 2920‐day‐long GOLF observations is presented and its results discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

太阳活动区δ黑子的研究进展

对太阳活动区δ黑子的研究有着非常重要的意义。因为几乎所有大耀斑都产生在δ黑子中，近３０多年来对δ黑子的观测和研究，取得了长足的进步但仍有许多问题需要我们作进一步的研究和观测证实。在本文中总结了３０多年来对δ黑子的研究进展，着重讨论了δ黑子的形成，发展和衰亡，以及与耀斑的关系等方面取得的最新成果。