日面高纬黑子与太阳活动

利用云南天文台太阳黑子观测资料,对太阳活动第１９ 周至第２２ 周日面高纬度（ 高于４０°） 的黑子群进行了统计．结果表明：高纬黑子面积绝大部分小于１００ ,平均５６ ,寿命大部分为１ ～３ 天,平均４ 天;黑子分类绝大部分为ＡＸＸ、ＨＳＸ、ＢＸＯ,其中ＡＸＸ 约占总数的一半．高纬黑子在日面南北半球上的不对称分布可用来预报该太阳周内的太阳活动在南北半球上的主次．由此预报２３ 周太阳活动将在南半球更活跃     

AR5395的黑子群特征

5395黑子群是1989年3月6日由日面东边缘转出来,于3月19日转到日面西边缘。3月12.8日过日面中心经圈。它的日面坐标是N34,L257。 该黑子群是第20太阳活动周以来面积最大的黑子群,且出现在30°以上的高纬度区域,更为罕见。它在通过日面期间,频繁地产生耀斑活动(共194个Hα耀斑),其     

近三个太阳活动周大黑子群的日面经度分布

本文对19、20、21太阳活动周的E、F型别黑子群进行了统计分析,得到:1.大黑子群日面经度随时间(用太阳自转周表示)的分布呈现“V”和“∧”形状;2.三个活动周大黑子群数按经度分布都有两个峰值。     

YR80—575号活动区的大黑子群

在国际太阳活动峰年期间,云南天文台观测到80—575号活动区,日面坐标S12L97,过中经日期11月11.7日,从11月5日到17日连续观测13天。 该活动区在日面通过期间,频繁地爆发耀斑,其中有一部分耀斑有强烈的x-线和短波突然中断事件相伴生。11月6日0542UT.,发生的一个X9/3B级耀斑伴生的X级x-线事件,强烈程度仅次于1978年7月11日的那次。 该活动区的形态特征之一是它的黑子群为第21太阳活动周以来面积最大的一群。它是云台80—529老活动的回归黑子群,许多新黑子在老黑子的周围浮现,从而变成一个非常复杂的FKC型黑子群,面积大,磁场梯度大,具有δ-结构。全群的平均磁场强度约为2000高斯,在几个主黑子中测量到最大磁场为3300高斯。 这个复杂的黑子群中,观测到了强烈的运动、旋转,分离,合并和黑子间的相互作用。老黑子中发现一个反常光桥,它是在两个本影合并起来时形成,而不象通常在黑子将分裂时出现。     

1989年3月和8月太阳大事件的日地系统整体行为研究

1989年3月日面出现了近四十年来最大的黑子群,发生了剧烈的太阳活动,产生了重大的地球物理效应。对这些事件的联测取得了大量日地物理的资料。为了推动进一步的分析和研究,中国科学院第22周太阳活动峰年日地系统整体行为研究专家组于1990年4月23日至26日在北京召开了“1989年3月和8月重大日地事件观测与分析研     

近三个太阳活动周黑子群的日面分布

本文用云南天文台黑子目视观测资料,作出了黑子的纬度分布图。从对十九、二十、二十一太阳活动周大面积黑子的纬度分布统计中,得出了和黑子周期有关的一些有意义的结果。     

AR5060黑子的形态分析(英文)

紫台观测编号为1988年第115号黑子群(Boulder编号为5060)是1988年6月26日由日面东边缘转出来,于7月9日转到日面西边缘背后,在7月18日过日面中心经圈,历时共13天。这个黑子群的日面坐标是S20和L5。 该黑子群比较大而复杂。在它通过日面期间,最大时的较正面积达2834(以半球面积的百万分之一为单位),这是从第20周至88年以来所观测到的面积最大的黑子群。此黑子群的型别(按麦氏分类)属最复杂的类型,基本上一直保持为FKC型。在6月26日从日面东边缘转出来时,黑子群呈现为一种异常排列,即其前导黑子位于高纬度,后随黑子处于低纬度,而且呈现明显的旋转运动,其转动方向是反时针的。它在过日面期间还不断的有自身的分裂和移动等特性。另外,该黑子群的磁性结构也异常复杂,在经过日面期间始终为δ结构。基于以上这些形态特征,促使这黑子群在通过日面这段时间内,先后产生了一系列的耀斑活动(其中有44个C级和13个M级的X射线耀斑),并大都伴随着显著的射电爆发,而且引起了多次相应的电离层突然骚动(SID)(有60个耀斑伴随着相应的电离层突然骚扰)。     

太阳整体行为研究

黑子相对数与黑子群在日面纬度上分布的蝴蝶图表征着太阳长期活动演化的特征，本文主要对这二者尤其是后者进行了研究。太阳活动在日面上分布表现为不对称，这是近30年太阳物理研究的主要内容之一。本文对这一领域进行了详细调研，发现太阳活动的南北半球分布不对称性的确存在，是否存在东西半球分布不对称目前还没有定论，但在日面经度上的分布肯定是不均匀的。本文还利用太阳22周活动极大时期X射线（Imp≥M1.0）耀斑事件进行了统计分析，给出了不对称演化特征，发现不对称性并不是事件活动剧烈程度的函数。统计分析表现21周太阳活动既不是已往方面中所述的南半球占优，也不是北半球占优。本文总结了以往对太阳长期活动特征研究的结论，也分析了黑子面积描述的活动周期特征，发现可用一个二参数函数来描述太阳活动周，这个结论对太阳长期活动预防是有用的。本文还详细解剖了蝴蝶图，揭示了其所含的物理信息，同时将不对称研究引入到这种解剖工作中，或是定量再现已有的一些定律，一些效应，或是揭示一些新的长期活动特征。本文最后对太阳长期活动预报方法和预报结构进行了总结，21－23周的预报事例说明前兆因子方法比其它方法要好。本文用Moscow中子监测值对23周作了预报，其峰值为151．1（月平均黑子相对数），对23周事例的总结分析表明其峰值为162．3。     

21～24太阳活动周首个高纬黑子和首个X级耀斑的半球特点与太阳活动的南北不对称性的关系

利用GOES和SDO卫星监测的太阳软X射线耀斑的数据,发现在21~24太阳活动周期间,第1个X级耀斑与第1个高纬黑子都出现在同一半球。与高纬黑子表征的太阳活动南北半球的不对称性一样,一个太阳活动周第1个X级耀斑的出现,很可能预示着首先出现X级耀斑的半球,其太阳活动将比另一半球更剧烈。     

太阳黑子的世纪周期及对24、25活动周的预报

太阳活动除了具有公认的11 a周期以外,还存在着一个80～120 a变化的世纪周期,也称为Gleissberg周期.使用傅里叶变换和小波分析的方法,分析了1700～2008年的年均黑子数世纪周期的变化规律.得到结果:在太阳活动世纪周期的低谷期,所对应11 a太阳周的极大年和极小年的黑子数目都比其他太阳周的低.在这300多年里,世纪周期的周期长度也有变化.由世纪周期的变化趋势,预测第24、25太阳活动周将处于世纪周期的低谷期.通过对以前3个世纪周期的谷期黑子数求平均的方法,得到第24,25太阳周极大年年均黑子数为63.6±21.1,极小年的为2.2±2.1.这些结果有助于理解当前太阳活动反常宁静这一现象.     

On the origin of the solar system and the exceptional position of the Sun in the Galaxy

The solar system's position in the Galaxy is an exclusive one, since the Sun is close to the corotation circle, which is the place where the angular velocity of the galactic differential rotation is equal to that of density waves displaying as spiral arms. Each galaxy contains only one corotation circle; therefore, it is an exceptional place. In the Galaxy, the deviation of the Sun from the corotation is very small — it is equal to ΔR/R _⊙≈0.03, where ΔR=R _c ?R _⊙,R _c is the corotation distance from the galactic center andR _⊙ is the Sun's distance from the galactic center. The special conditions of the Sun's position in the Galaxy explain the origin of the fundamental cosmogony timescalesT ₁≈4.6×10⁹ yr,T ₂?10⁸ yr,T ₃?10⁶ yr detected by the radioactive decay of various nuclides. The timescaleT ₁ (the solar system's ‘lifetime’) is the protosolar cloud lifetime in a space between the galactic spiral arms. The timescaleT ₂ is the presolar cloud lifetime in a spiral arm.T ₃ is a timescale of hydrodynamical processes of a cloud-wave interaction. The possibility of the natural explanation of the cosmogony timescales by the unified process (on condition that the Sun is near the state of corotation) can become an argument in favour of the fact that the nearness to the corotation is necessary for the formation of systems similar to the Solar system. If the special position of the Sun is not incidental, then the corotation circles of our Galaxy, as well as those of other galaxies, are just regions where situations similar to ours are likely to be found.     

Perturbations by the oblateness of the Earth and by the planets in the motion of the Moon

Perturbations in the motion of the Moon are computed for the effect by the oblateness of the Earth and for the indirect effect of planets. Based on Delaunay's analytical solution of the main problem, the computations are performed by a method of Fourier series operation. The effect of the oblateness of the Earth is obtained to the second order, partly adopting an analytical evaluation. Both in longitude and latitude are found a few terms whose coefficient differs from the current lunar ephemeris based on Brown's theory by about 0.01. While, concerning the indirect effect of planets, several periodic terms in the current ephemeris seem to have errors reaching 0.05.As for the secular variations of and due to the figure of the Earth and the indirect effect of planets, the newly-computed values agree within 1/cy with Brown's results reduced to the same values of the parameters. Further, the accelerations in the mean longitude, and caused by the secular changes in the eccentricity of the Earth's orbite and in the obliquity of the ecliptic are obtained. The comparison with Brown shows an agreement within 0.3/cy² for the former cause and 0.02/cy² for the latter. An error is found in the argument of the principal term for the perturbations due to the ecliptic motion in the current ephemeris.Proceedings of the Conference on Analytical Methods and Ephemerides: Theory and Observations of the Moon and Planets. Facultés universitaires Notre Dame de la Paix, Namur, Belgium, 28–31 July, 1980.     

On the model of the accumulation of the moon compatible with the data on the composition and the age of lunar rocks

It is suggested that the overall early melting of the lunar surface is not necessary for the explanation of facts and that the structure of highlands is more complicated than a solidified anorthositic ‘plot’. The early heating of the interior of the Moon up to 1000K is really needed for the subsequent thermal history with the maximum melting 3.5 × 10⁹ yr ago, to give the observed ages for mare basalts. This may be considered as an indication that the Moon during the accumulation retained a portion of its gravitational energy converted into heat, which may occur only at rapid processes. A rapid (t < 10³ yr) accretion of the Moon from the circumterrestrial swarm of small particles would give necessary temperature, but it is not compatible with the characteristic time 10⁸ yr of the replenishment of this swarm which is the same as the time-scale of the accumulation of the Earth. It is shown that there were conditions in the circumterrestial swarm for the formation at a first stage of a few large protomoons. Their number and position is evaluated from the simple formal laws of the growth of satellites in the vicinity of a planet. Such ‘systems’ of protomoons are compared with the observed multiple systems, and the conclusion is reached that there could have been not more than 2–3 large protomoons with the Earth. The tidal evolution of protomoon orbits was short not only for the present value of the tidal phase-lag but also for a considerably smaller value. The coalescence of protomoons into a single Moon had to occur before the formation of the observed relief on the Moon. If we accept the age 3.9 × 10⁹ yr for the excavation of the Imbrium basin and ascribe the latter to the impact of an Earth satellite, this collision had to be roughly at 30R, whereR is the radius of the Earth, because the Moon at that time had to be somewhere at this distance. Therefore, the protomoons had to be orbiting inside 20–25R, and their coalescence had to occur more than 4.0x10⁹ yr ago. The energy release at coalescence is equivalent to several hundred degrees and even 1000 K. The process is very rapid (of the order of one hour). Therefore, the model is valid for the initial conditions of the Moon.     

On the theory of the oblateness of the Sun

In this paper we first emphasize why it is important to know the successive zonal harmonics of the Sun's figure with high accuracy: mainly fundamental astrometry, helioseismology, planetary motions and relativistic effects. Then we briefly comment why the Sun appears oblate, going back to primitive definitions in order to underline some discrepancies in theories and to emphasize again the relevant hypotheses. We propose a new theoretical approach entirely based on an expansion in terms of Legendre's functions, including the differential rotation of the Sun at the surface. This permits linking the two first spherical harmonic coefficients (J ₂ and J ₄) with the geometric parameters that can be measured on the Sun (equatorial and polar radii). We emphasize the difficulties in inferring gravitational oblateness from visual measurements of the geometric oblateness, and more generally a dynamical flattening. Results are given for different observed rotational laws. It is shown that the surface oblateness is surely upper bounded by 11 milliarcsecond. As a consequence of the observed surface and sub-surface differential rotation laws, we deduce a measure of the two first gravitational harmonics, the quadrupole and the octopole moment of the Sun: J ₂=−(6.13±2.52)×10⁻⁷ if all observed data are taken into account, and respectively, J ₂=−(6.84±3.75)×10⁻⁷ if only sunspot data are considered, and J ₂=−(3.49±1.86)×10⁻⁷ in the case of helioseismic data alone. The value deduced from all available data for the octopole is: J ₄=(2.8±2.1)×10⁻¹². These values are compared to some others found in the literature. Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1005238718479     

Accounting for the viscosity of the fluid core in the problem of the physical libration of the moon

A two-component theoretical model of the physical libration of the Moon in longitude is constructed with account taken of the viscosity of the core. In the new version, a hydrodynamic problem of motion of a fluid filling a solid rotating shell is solved. It is found that surfaces of equal angular velocity are spherical, and a velocity field of the fluid core of the Moon is described by elementary functions. A distribution of the internal pressure in the core is found. An angular momentum exchange between the fluid core and solid mantle is described by a third-order differential equation with a right-hand side. The roots of a characteristic equation are studied and the stability of rotation is proved. A libration angle as a function of time is found using the derived solution of the differential equation. Limiting cases of infinitely large and infinitely small viscosity are considered and an effect of lag of a libration phase from a phase of action of an external moment of forces is ascertained. This makes it possible to estimate the viscosity and sizes of the lunar fluid core from data of observations.     

On some problems concerning the calculation of the form of the magnetopause and the electric field on the magnetopause in the framework of the continuum medium model

In order to understand the reason of the existence of the electric field in the magnetosphere, and for the theoretical evaluation of its value, it is necessary to find the solution of the problem of determination of the magnetosphere boundary form in the frameworks of the continuum medium model which takes into account part of the magnetospheric plasma movement in supporting the magnetospheric boundary equilibrium. A number of problems for finding the distribution of the pressure, the density, the magnetic field and the electric field on the particular tangential discontinuity is considered in the case when the form of discontinuity is set (the direct problem) and a number of problems for finding the form of the discontinuity and the distribution of the above-mentioned physical quantities on the discontinuity is considered when the law of the change of the external pressure along the boundary is set (for example, with the help of the approximate Newton equation). The problem which is considered here, which deals with the calculation of the boundary form and with the calculation of the distribution of the corresponding physical quantities on the discontinuity of the 1st kind for the compressible fluid with the magnetic field with field lines which are perpendicular to the plane of the flow in question, concerns the last sort of problems. The comparison of the results of the calculation with the data in the equatorial cross-section of the magnetosphere demonstrates that the calculated form of the boundary, the value of the velocity of the return flow and the value of the electric field on the magnetopause, agree satisfactorily with the observational data.