共查询到19条相似文献，搜索用时 218 毫秒
1.
该文通过综述相关研究成果,对日冕亮点的观测特征和供能机制进行了总结和评论.日冕亮点是发生在过渡区和低日冕的小尺度局地增亮现象,经常在X射线和极紫外波段观测到,其寿命在5～40 h之间.日冕亮点的产生和演化与双极磁场的相互作用紧密相关.对于日冕亮点的供能机制,目前主要存在三种观点:(1)磁场对消的观点,当不同极性的磁场区域相互靠近时,局地发生磁重联,并在重联区域加热等离子体,从而导致X射线和极紫外辐射的增强;(2)分隔线重联,与日冕亮点相联系的磁场结构可以形成分隔线重联位形,沿分隔线的快速磁场重联导致过渡区和日冕局地的等离子体被加热,从而产生日冕亮点;(3)光球水平运动所诱发的电流片为亮点提供了能量来源.近期研究表明,三种机制可能同时作用,为亮点提供所需的能量. 相似文献
2.
利用怀柔太阳磁场望远镜,我们对太阳宁静区光球和色球磁场进行了观测。日面中心到边缘的观测表明,太阳宁静区中的小尺度磁结构在从光球到色球的扩展过程中变化不大。日面边缘的观测表明,小尺度磁结构的水平分量在光球和色球都不大。对极区和赤道边缘纵向磁场的比较发现,极区磁场与赤道边缘磁场有着不同的磁结构特性 相似文献
3.
在太阳光球表面出现的磁亮点是目前观测手段能够分辨的最小磁结构,也被认为是日冕中的磁绳在光球足点运动的可靠示踪者。磁亮点的尺度约为100～300 km,寿命从几分钟到几十分钟。磁亮点被观测到不仅具有漩涡运动现象,还有很强的振荡现象。磁亮点是在磁通量管的对流坍缩过程中形成的,这已被观测和数值模拟所验证;磁亮点的运动导致其所在的磁通量管产生振荡,或者与其他磁通量管发生扭绞。理论上认为,这些振荡会以波的形式向色球和日冕传送能量,而磁通量管之间的扭绞会在色球和日冕中发生磁重联并释放能量,从而加热色球和日冕。为了解开日冕加热和色球加热等未解之谜,对磁亮点的研究显示出它特殊的重要性。对磁亮点的基本特征、形成原理、观测证据、光球磁亮点和太阳大气其他亮点之间的关系,以及磁亮点对日冕加热贡献等方面进行了介绍和讨论。 相似文献
4.
汪景琇 《中国天文和天体物理学报》1995,(3)
本文讨论了从太阳光球向日冕传输磁能和磁复杂性的过程。活动日冕，作为由电磁场和粒子组成的系统，其唯一的开场表面是太阳光球。光球层等离子体的运动和磁场的相互作用，是造成磁能和磁复杂性向日冕传播的主要根源；同时，光球上的耗散过程也对日冕磁能和磁复杂性的积累有不可忽视的贡献。 相似文献
5.
我们在文[1]的启发下,计算了磁中性线附近异极性磁区相互入侵(或挤压)引起的等离子体动力学问题。气体初态取用流行的宁静太阳光球色球大气模型,即非等温的密度指数变化的重力分层大气。采用Lagrangian格式数值求解自洽的MHD方程,这可使入侵力学变得直观明显——磁场随流体而运动。我们的新结果是入侵流动在光球低层产生出强的水平磁场(即强的横向场),但光球高层和色球低层的磁结构却变化不大,有力地支持了文[13]提出的光球色球里可能出现磁流体力学间断面的概念。入侵确实在磁中性线附近建立了电流片,但这电流片主要在光球低层,其量级和观测一致。另外还显示垂直下降运动也可能导致异极磁区的入侵。尽管在MHD~1方程里包含了电阻耗散和热传导流,但计算证明它们对入侵力学影响不大,热传导的作用只是使气体温度分布逐渐趋于宁静太阳分布(尽管高度变了)。 相似文献
6.
本讨论了从太阳光球向日冕传输磁能和磁复杂性的过程。活动日冕，作为由电磁场和粒子组成的系统，其唯一的开场表面是太阳光球，光球层等离子体的运动和磁场的相互作用，是造成磁能和磁复杂性向日冕传输的主要根据；同时，光球上的耗散过程也对日冕磁能和磁复杂性的积累有不可忽视的贡献。 相似文献
7.
利用Hinode卫星观测的单色像和磁图,对出现在黑子半影内的35对偶极运动磁特征进行形态特征、运动速度以及低层太阳大气响应3方面的研究,得出以下结论:(1)偶极运动磁特征正负两极成对出现在黑子半影较垂直的磁场之间并向着半影外边界运动,间接验证了偶极运动磁特征起源于黑子半影水平磁场,在2-8小时的时间间隔内,同一位置上会反复出现形态特征和运动速度相似的偶极运动磁特征,为海蛇状磁力线模型提供了证据支持. (2)光球和色球在偶极运动磁特征向外运动过程中会出现增亮,说明偶极运动磁特征会加热中低层太阳大气.(3)偶极运动磁特征的出现位置和半影磁场结构分布符合非梳子状黑子半影结构特征. 相似文献
8.
本论文可分为两个部分,第一部分系统地综述了太阳大气中的小尺度活动现象,并给出了详细的统计结果。小尺度磁场的对消激发小尺度活动现象。这些磁场显著影响太阳大气的结构和动力学特征,这产场影响能量从小阳大气的结构和动力学特征,如这些磁场影响能量从太阳大气的低层向高层传输,针状体动力学（小尺度磁活动）能够把物质从光球输送到日冕,及小尺度磁场对消产生的Ｘ射线亮点等等。近几年,大多数太阳物理学家认为小尺度磁场对 相似文献
9.
戴子高 《中国天文和天体物理学报》1997,(2)
本文研究了中子星的热演化、自转演化和磁场演化的相互影响．考虑了一个自洽模型：中子星因磁偶极辐射而自转减慢，在内部产生某些加热过程，中子星磁场通过壳层的欧姆耗散来衰减．结果表明，磁场衰减提高了加热过程的重要性；相反，加热效应减慢了磁衰减．因此可以得出，中子星的热、自转和磁场也许不是独立演化的．不仅如此，这些演化与初始条件有关，因此，人们也许可以从射电和Ｘ射线观测对脉冲星年龄、初始磁场和周期给出某些限制． 相似文献
10.
本研究了中子星的热演化，自转演化和磁场演化的相互影响，考虑了一个自洽模型，中子星因磁偶极辐射而自转减慢，在内部产生某些加热过程，中子星磁场通过壳层的欧姆耗散来衰减。结果表明，磁场衰减提高了加热过程的重要性，相反，加热效应减慢了磁衰减，因此可以得出，中子星的热，自转和磁场也许不是独立演化的，不仅如此，这些演化与初始条件有关，因此，人们也许可以从射电和Ｘ射线观测对脉冲星年龄，初始磁场和周期给出某些限 相似文献
11.
Kenneth H. Schatten 《Solar physics》2009,255(1):3-38
Photospheric ephemeral regions (EPRs) cover the Sun like a magnetic carpet. From this, we update the Babcock – Leighton solar
dynamo. Rather than sunspot fields appearing in the photosphere de novo from eruptions originating in the deep interior, we consider that sunspots form directly in the photosphere by a rapid accumulation
of like-sign field from EPRs. This would only occur during special circumstances: locations and times when the temperature
structure is highly superadiabatic and contains a large subsurface horizontal magnetic field (only present in the Sun’s lower
latitudes). When these conditions are met, superadiabatic percolation occurs, wherein an inflow and downflow of gas scours
the surface of EPRs to form active regions. When these conditions are not met, magnetic elements undergo normal percolation,
wherein magnetic elements move about the photosphere in Brownian-type motions. Cellular automata (CA) models are developed
that allow these processes to be calculated and thereby both small-scale and large-scale models of magnetic motions can be
obtained. The small-scale model is compared with active region development and Hinode observations. The large-scale CA model offers a solar dynamo, which suggests that fields from decaying bipolar magnetic regions
(BMRs) drift on the photosphere driven by subsurface magnetic forces. These models are related to observations and are shown
to support Waldmeier’s findings of an inverse relationship between solar cycle length and cycle size. Evidence for significant
amounts of deep magnetic activity could disprove the model presented here, but recent helioseismic observations of “butterfly
patterns” at depth are likely just a reflection of surface activity. Their existence seems to support the contention made
here that the field and flow separate, allowing cool, relatively field-free downdrafts to descend with little field into the
nether worlds of the solar interior. There they heat by compression to form a hot solar-type Santa Ana wind deep below active
regions. 相似文献
12.
Harvey Karen L. Jones Harrison P. Schrijver Carolus J. Penn Matthew J. 《Solar physics》1999,190(1-2):35-44
Simultaneous measurements of the magnetic fields in the photosphere and chromosphere were used to investigate if magnetic
flux is submerging at sites between adjacent opposite polarity magnetic network elements in which the flux is observed to
decrease or `cancel'. These data were compared with chromospheric and coronal intensity images to establish the timing of
the emission structures associated with these magnetic structures as a function of height. We found that most of the cancelation
sites show either that the bipole is observed longer in the photosphere than in the chromosphere and corona (44%) or that
the timing difference of the disappearance of the bipole between these levels of the atmosphere is unresolved. The magnetic
axis lengths of the structures associated with the cancelation sites are on average slightly smaller in the chromosphere than
the photosphere. These observations suggest that magnetic flux is retracting below the surface for most, if not all, of the
cancelation sites studied. 相似文献
13.
R. Muller 《Solar physics》1985,100(1-2):237-255
The observed properties of the small-scale features visible in the quiet photosphere — the granulation, of convective origin, and the network bright points, associated with kG magnetic fields — are described. The known properties of the magnetic flux tubes associated with network bright points are also presented. Empirical models derived from the observations are discussed, as well as a few theoretical models of particular importance for the understanding of the origin of the small-scale features of the quiet photosphere. Finally, the observational evidences showing that the structure of the granulation and of the photospheric network are varying over the solar cycle are reported. 相似文献
14.
Simultaneous observations made at several wavelengths in microwave range using the high spatial resolution of radiotelescope RATAN-600 make it possible to develop methods of measuring the magnetic fields in the solar corona and the chromosphere. In this paper we develop a method of measuring the magnetic fields from thermal bremsstrahlung and demonstrate it, using observations of a flocculus (plage) during August 1–3, 1977. The observations show that the flocculus under investigation possessed bipolar magnetic structure with peak to peak amplitude of magnetic field strength of about 40 G at the level of the upper chromosphere and the transition region (with a r.m.s. error of 5.7 G for favourable conditions). The radio astronomical map of the magnetic field is in agreement with the Mt. Wilson magnetic field map to within the experimental error. It follows that the average longitudinal magnetic field above the flocculus does not drop significantly with height above the photosphere up to the CCTR (chromosphere-corona transition region). An analysis of the spectra of polarized radio emission also gives an opportunity to determine the temperature gradient in the CCTR (which proved to amount to about 1000 K km-1 and to follow their variation with height. 相似文献
15.
Microwave emission from solar active regions at frequencies above 4 GHz is dominated by gyroresonance opacity in strong coronal magnetic fields, which allows us to use radio observations to measure coronal magnetic field strengths. In this paper we demonstrate one powerful consequence of this fact: the ability to identify coronal currents from their signatures in microwave images. Specifically, we compare potential-field (i.e., current-free) extrapolations of photospheric magnetic fields with microwave images and are able to identify regions where the potential extrapolation fails to predict the magnetic field strength required to explain the microwave images. Comparison with photospheric vector magnetic field observations indicates that the location inferred for coronal currents agrees with that implied by the presence of vertical currents in the photosphere. The location, over a neutral line exhibiting strong shear, is also apparently associated with strong heating. 相似文献
16.
S. Liu 《Astrophysics and Space Science》2014,351(2):409-416
Magnetic fields dominate most solar activities, there exist direct relations between solar flare and the distributions of magnetic field, and also its corresponding magnetic energy. In this paper, the statistical results about the relationships between the spatial magnetic field and solar flare are given basing on vector magnetic field observed by the Solar Magnetic Field Telescope (SMFT) at Huairou Solar Observing Station (HSOS). The spatial magnetic fields are obtained by extrapolated photosphere vector magnetic field observed by SMFT. There are 23 active regions with flare eruption are chosen as data samples, which were observed from 1997 to 2007. The results are as follows: 1. Magnetic field lines become lower after flare for 16 (69 %) active regions; 2. The free energy are decreased after flare for 17 (74 %) active regions. It can conclude that for most active regions the changes of magnetic field after solar flare re coincident with the previous observations and studies. 相似文献
17.
V. E. Abramov-Maksimov G. F. Vyalshin G. B. Gelfreikh V. I. Shatilov 《Solar physics》1996,164(1-2):333-343
In the present paper we present the results of measurement of magnetic fields in some sunspots at different heights in the solar atmosphere, based on simultaneous optical and radio measurements. The optical measurements were made by traditional photographic spectral observations of Zeeman splitting in a number of spectral lines originating at different heights in the solar photosphere and chromosphere. Radio observations of the spectra and polarization of the sunspot - associated sources were made in the wavelength range of 2–4 cm using large reflector-type radio telescope RATAN-600. The magnetic field penetrating the hot regions of the solar atmosphere were found from the shortest wavelength of generation of thermal cyclotron emission (presumably in the third harmonic of electron gyrofrequency). For all the eight cases under consideration we have found that magnetic field first drops with height, increases from the photosphere to lower chromosphere, and then decreases again as we proceed to higher chromosphere and chromosphere-corona transition region. Radio measurements were found to be well correlated with optical measurements of magnetic fields for the same sunspot. An alternative interpretation implies that different lines used for magnetic field measurements refer to different locations on the solar surface. If this is the case, then the inversion in vertical gradients of magnetic fields may not exist above the sunspots. Possible sources of systematic and random errors are also discussed. 相似文献
18.
M. I. Stodilka 《Kinematics and Physics of Celestial Bodies》2011,27(4):161-174
An integrated effect of small-scale magnetic fields on online absorption coefficient is analytically estimated. The formation
of magnetically sensitive Fe I lines under the conditions of undisturbed solar photosphere in the presence of small-scale
magnetic fields is studied. It is shown that these fields can broaden the wings of magnetically sensitive lines. 相似文献
19.
M. L. Demidov 《Journal of Astrophysics and Astronomy》2000,21(3-4):209-212
A comparison is made of observational data on the mean magnetic field of the Sun from several observatories (a selection of
published information and new measurements). Results of correlation and regression analyses of observations of background
magnetic fields at the STOP telescope of the Sayan solar observatory in different spectral lines are also presented. Results
obtained furnish an opportunity to obtain more unbiased information about largescale magnetic fields of the Sun and, in particular,
about manifestations of strong (kilogauss) magnetic fields in them. 相似文献