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1.
ＡＲ６６５９是２２周以来最重要的一个活动区，它爆发了２２周最强大的高能事件。本文用云南天文台的光球、色球精细结构照片和北京天文台怀柔站的磁场速度场资料，分析了该活动区磁场速度场的二维位形和大耀斑期间的演化特征。本文分析的４个大耀斑均爆发在中性线附近的Ｎ极区磁场梯度大的地方及色球速度场的红移区。偏带观测也显示耀斑物质是向红端移动的。耀斑波沿横场传播在离本黑子群几万至十几万公里的地方激起感生耀斑，在原生耀斑与感生耀斑之间往往有耀斑环相连。此外，本文还从演化特征出发分析了耀斑爆发前活动区等离子体的宏观不稳定性。 相似文献
2.
Shuo Wang Yuanyong Deng Rajmal Jain Vasyl Yurchyshyn Haimin Wang Yuanyuan Liu Zhiliang Yang 《Journal of Astrophysics and Astronomy》2008,29(1-2):57-61
In this paper, we study the evolution of vector magnetic field of AR 10656 by using the observations of Huairou Solar Observing Station (HSOS, China) and Big Bear Solar Observatory (BBSO, USA). The magnetic flux emergence and cancellation, and thus, magnetic nonpotential changes, are associated with the major flares in this active region. Compared with some other super-active regions, the evolution of magnetic morphologies and non-potentialities are relatively gradual, and thus the energy transportation and release are relatively slow. This gradual process may result in the recurrent flares of AR 10656. 相似文献
3.
Solar System Research - An active region (AR) of the sun is an area of strong magnetic field. Sunspots are frequently formed in an AR. Solar activity exhibits in the form of solar flares and... 相似文献
4.
R. K. Srivastava 《Astrophysics and Space Science》1986,120(2):239-252
BV optical flares of AR Lacertae, found in 1979 observations, are presented and their features are discussed. The effect of wave migration and the significance levels of flares originating around both eclipses have been estimated. Flare features suggest that both the components of AR Lac have spotted regions and show activity. The varying amplitudes of flares indicate varying degrees of activity. These results are well supported by observations in other wavelength regions. 相似文献
5.
Sara F. Martin 《Solar physics》1980,68(2):217-236
Prefiare conditions, changes and events are loosely categorized as distinct, evolutionary or statistical. Distinct preflare phenomena are those for which direct physical associations with flares are implied. Also, they are not known to occur in a like manner during the absence of flares. These include the early stage of filament eruptions within active centers, preflare vortical structures, some transient X-ray emitting features, 5303 Å accelerating coronal arches, and increases in circular polarization at cm wavelengths. Evolutionary preflare changes are considered to be any long-term effect that may be related to the flare build-up even though the same changes may occur in the absence of flares. This category covers the development of current sheets or strongly sheared magnetic fields, evolving magnetic features, emerging flux regions, the development of satellite fields around sunspots, the evolution of reverse polarity field configurations, the merging of adjacent active centers, sunspot motions and the development of velocity patterns. Statistical preflare changes logically include both distinct and evolutionary preflare changes. However, in addition, there are preflare conditions and events that are not necessarily linked to the flare in either a direct physical or indirect evolutionary way. Such parameters or events that may only be statistically significant are certain magnetic field properties, the brightness of active centers at various wavelengths, the previous occurrence of flares and subflares, increased turbulence in filaments and certain radio events. 相似文献
6.
The NOAA active region (AR) 11029 was a small but highly active sunspot region which produced 73 GOES soft X-ray flares during its transit of the disk in late October 2009. The flares appear to show a departure from the well-known power law frequency-size distribution. Specifically, too few GOES C-class and no M-class flares were observed by comparison with a power law distribution (Wheatland, Astrophys. J. 710, 1324, 2010). This was conjectured to be due to the region having insufficient magnetic energy to power the missing large events. We construct nonlinear force-free extrapolations of the coronal magnetic field of AR 11029 using data taken on 24 October by the SOLIS Vector SpectroMagnetograph (SOLIS/VSM) and data taken on 27 October by the Hinode Solar Optical Telescope SpectroPolarimeter (Hinode/SP). Force-free modeling with photospheric magnetogram data encounters problems, because the magnetogram data are inconsistent with a force-free model. We employ a recently developed “self-consistency” procedure which addresses this problem and accommodates uncertainties in the boundary data (Wheatland and Régnier, Astrophys. J. 700, L88, 2009). We calculate the total energy and free energy of the self-consistent solution, which provides a model for the coronal magnetic field of the active region. The free energy of the region was found to be ≈?4×1029?erg on 24 October and ≈?7×1031?erg on 27 October. An order of magnitude scaling between RHESSI non-thermal energy and GOES peak X-ray flux is established from a sample of flares from the literature and is used to estimate flare energies from the observed GOES peak X-ray flux. Based on the scaling, we conclude that the estimated free energy of AR 11029 on 27 October when the flaring rate peaked was sufficient to power M-class or X-class flares; hence, the modeling does not appear to support the hypothesis that the absence of large flares is due to the region having limited energy. 相似文献
7.
P. Démoulin C. H. Mandrini M. G. Rovira J. C. Hénoux M. E. Machado 《Solar physics》1994,150(1-2):221-243
We present a detailed analysis of the magnetic topology of AR 2776 together with Hα UV, X-rays, and radio observations of the November 5, 1980 flares in order to understand the role of the active region large-scale
topology on the flare process. As at present the coronal magnetic field is modeled by an ensemble of sub-photospheric sources
whose positions and intensities are deduced from a least-square fit between the computed and observed longitudinal magnetic
fields. Charges and dipole representations are shown to lead to similar modeling of the magnetic topology provided that the
number of sources is great enough. However, for AR 2776, departure from a potential field has to be taken into account, therefore
a linear force-free field extrapolation is used.
The locations of the four bright off-band Hα kernels in quadrupolar active regions have been studied previously. In this new study the active region is bipolar and shows
a two-ribbon structure. We show that these two ribbons are a consequence of the bipolar photospheric field (the four kernels
of quadrupolar regions merge into two bipolar regions). The two ribbons are found to be located at the intersection of the
separatrices with the chromosphere when the shear, deduced from the fibril direction, is taken into account.
This study supports the hypothesis that magnetic energy is stored in field-aligned currents and released by magnetic reconnection
at the location of the separator, before being transported along field lines to the chromospheric level. It is also possible
that part of the magnetic energy could be stored and released on the separatrices. Our study shows that meeting just one of
two conditions- the presence of intense coronal currents or of a separator in a magnetic field configuration - is not sufficient
for flaring. In order to release the stored energy, the coronal currents need either to be formed along the separatrices or
to be transported towards the separator or separatrices. The location of the observed photospheric current concentrations
on the computed separatrices supports this view.
Member of the Carrera del Investigador Científico, CONICET. 相似文献
8.
Relationship between magnetic field evolution and flaring sites in AR 6659 in June 1991 总被引：2，自引：0，他引：2
B. Schmieder M. J. Hagyard Guoxiang Ai Hongqi Zhang B. Kalmán L. Györi B. Rompolt P. Démoulin M. E. Machado 《Solar physics》1994,150(1-2):199-219
During the international campaign of June 1991, the active region AR 6659 produced six very large, long-duration flares (X10/12)
during its passage across the solar disk. We present the characteristics of four of them (June 4, 6, 9, 15). Precise measurements
of the spot motions from Debrecen and Tokyo white-light pictures are used to understand the fragmentation of the main sunspot
group with time. This fragmentation leads to a continuous restructuring of the magnetic field pattern while rapid changes
are evidenced due to fast new flux emergence (magnetograms of MFSC, Huairou). The first process leads to a shearing of the
field lines along which there is energy storage; the second one is the trigger which causes the release of energy by creating
a complex topology. We conjecture that these two processes with different time scales are relevant to the production of flares. 相似文献
9.
《天文和天体物理学研究(英文版)》2017,(8)
We analyze sunspot rotation and magnetic transients in NOAA AR 11429 during two X-class(X5.4 and X1.3)flares using data from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory.A large leading sunspot with positive magnetic polarity rotated counterclockwise.As expected,the rotation was significantly affected by the two flares.Magnetic transients induced by the flares were clearly evident in the sunspots with negative polarity.They were moving across the sunspots with speed of order 3-7 km s~(-1).Furthermore,the trend of magnetic flux evolution in these sunspots exhibited changes associated with the flares.These results may shed light on understanding the evolution of sunspots. 相似文献
10.
利用云南天文台声光频谱议１９９１年６月观测到的来自６６５９活动区的米波射电爆发记录,及其光学活动、磁场速度场的资料,作了分析研究。得到了一些有意义的结果 相似文献
11.
12.
1 INTRODUCTIONRecently Bao, Zhang, Ai, and Zhang (1999), using Huairou vector magnetograph data,have shown that the average current helicity (h.) or the curreflt helicity imbalance ph of activeregions change rapidly after so1ar flares. Up'an the onset of flares it tends to decrease for a fewhours and then to increase again, whereas ifQ some cases the flare promotes an increase in thecurrent helicity The observations led to tbe fol1owing conclusions: (1) raPid and substantialchanges of c… 相似文献
13.
We analyze large-scale H-alpha movies of the large spot group of Sept. 13–26, 1963, together with radio, ionospheric and magnetic field data as well as white light pictures. The evolution of the group and associated magnetic fields is followed, and the positions of solar flares relative to the fields are noted, along with their morphology. Although the magnetic field is deformed in time, characteristic field structures may be traced through the deformation as the seat of recurrent homologous flares.We find that most flares are homologous, and some are triggered by disturbances elsewhere in the region. We note events produced by surges falling back to the surface, and one flare initiated by a bright bead seen to fly across the region. In almost every case of an isolated type III radio burst, a corresponding H-alpha brightening could be found, but not all flares produced bursts. Flares close to the sunspots are most likely to produce radio bursts. Flare surface waves in the region all travel out to the west, because of more open magnetic field structure there. In one case (Sept. 25) a wave is turned back by the closed field structure to the east.In almost all cases the time association of radio or ionospheric events is with the beginning of the flare or with the flash phase.Several morphological classes of flares are noted as recurrent types. 相似文献
14.
G. D. R. Attrill L. K. Harra L. van Driel-Gesztelyi M. J. Wills-Davey 《Solar physics》2010,264(1):119-147
We study two CME events on 13 and 14 December 2006 that were associated with large-scale dimmings. We study the eruptions
from pre-event on 11 December through the recovery on 15 December, using a combination of Hinode/EIS, SOHO/EIT, SOHO/MDI, and MLSO Hα data. The GOES X-class flares obscured the core dimmings, but secondary dimmings developed
remote from the active region (AR) in both events. The secondary dimmings are found to be formed by a removal of bright coronal
material from loops in the plage region to the East of the AR. Using Hinode/EIS data, we find that the outflows associated with the coronal-dimming regions are highly structured. The concentrated outflows
are located at the footpoints of coronal loops (which exist before, and are re-established after, the eruptions), and these
are correlated with regions of positive magnetic elements. Comparative study of the Hinode/EIS and SOHO/EIT data shows that the reduction in outflow velocity is consistent with the recovery in intensity of the studied
regions. We find that concentrated downflows develop during the recovery phase of the dimmings and are also correlated with
the same positive magnetic elements that were previously related to outflows. 相似文献
15.
Studies of solar flares indicate that the mechanism of flares is magnetic in character and that the coronal magnetic field is a key to understanding solar high-energy phenomena. In our ongoing research we are conducting a systematic study of a large database of observations which includes both coronal structure (from the Soft X-ray Telescope on the Yohkoh spacecraft) and photospheric vector magnetic fields (from the Haleakala Stokes Polarimeter at Mees Solar Observatory). We compare the three-dimensional nonlinear force-free coronal magnetic field, computed from photospheric boundary data, to images of coronal structure. In this paper we outline our techniques and present results for active region AR 7220/7222. We show that the computed force-free coronal magnetic field agrees well with Yohkoh X-ray coronal loops, and we discuss the properties of the coronal magnetic field and the soft X-ray loops. 相似文献
16.
Based on a topological model for the magnetic field of a solar active region (AR), we suggest a criterion for the existence of magnetic null points on the separators in the corona. With the problem of predicting solar flares in mind, we have revealed a model parameter whose decrease means that the AR evolves toward a major eruptive flare. We analyze the magnetic field evolution for AR 9077 within two days before the Bastille Day flare on July 14, 2000. The coronal conditions are shown to have become more favorable for magnetic reconnection, which led to a 3B/X5.7 eruptive flare. 相似文献
17.
The global 3-dimensional topology of the magnetic field of the weakly flaring active region AR 5420 in the early phase has been estimated using a series of photospheric longitudinal and vector magnetogams together with Hα filtergrams and white-light images. As a physical model for this task, we have used the assumption ofa force-free magnetic field character. An arcade-like structure of the magnetic field has been identified in the preflare phase with an apparent sheared configuration already present in the current-free field case. This system might have been an important source of generation of a field-aligned current system for the eruptions that followed. That was, in particular, suggeted by a significant extension of the active region area in the observation period from June 22 to 25, 1984, that resulted in a stronger shear of the detected arcade-like system. The atmospheric electric currents generated in such a way and the transition triggered by a large-amplitude perturbation generated by new flux emergences on June 23 at this place together might be the reason of the sequence of flares observed. Despite the changes in the Hα structure, the global force-free character of the field did not change significantly over the time of observations. The invariance (in the first order) of the force-free (nearly current-free) character of the magnetic field is consistent with the occurrence of relatively small flares only. 相似文献
18.
AR5395及AR6659的贮能释能周期性 总被引：1，自引：0，他引：1
本文分析了了AR5395和AR6659的X射线耀斑活动周期性，耀斑强度周期的存在表明活动区的能量积累和释放过程具有可重复性，包括贮存的能量大小也具可重复性，计算得出AR5395的耀风强度周期为24．49小时，而AR6659的周期为57．39小时，耀斑指数按周期的分布证明在一个贮能周期中活动区贮存的能量大致相同，周期内的平均耀斑指数代表能量积累效率，AR6659较之AR5395有较长的能量积累周期和较高的能量积累效率．此外，本文还讨论了耀斑事件出现的周期．这种周期的长短代表活动区磁结构对于耀斑出现的稳定程度，并且，当活动区处于较高能量状态（即相对势场状态的偏离较大）时，出现耀斑不稳定性的可能性增加。 相似文献
19.
R. Chandra B. Schmieder C. H. Mandrini P. Démoulin E. Pariat T. Török W. Uddin 《Solar physics》2011,269(1):83-104
We present and interpret observations of two morphologically homologous flares that occurred in active region (AR) NOAA 10501
on 20 November 2003. Both flares displayed four homologous Hα ribbons and were both accompanied by coronal mass ejections
(CMEs). The central flare ribbons were located at the site of an emerging bipole in the centre of the active region. The negative
polarity of this bipole fragmented in two main pieces, one rotating around the positive polarity by ≈ 110° within 32 hours.
We model the coronal magnetic field and compute its topology, using as boundary condition the magnetogram closest in time
to each flare. In particular, we calculate the location of quasi-separatrix layers (QSLs) in order to understand the connectivity between the flare ribbons. Though several polarities were present in AR 10501,
the global magnetic field topology corresponds to a quadrupolar magnetic field distribution without magnetic null points.
For both flares, the photospheric traces of QSLs are similar and match well the locations of the four Hα ribbons. This globally
unchanged topology and the continuous shearing by the rotating bipole are two key factors responsible for the flare homology.
However, our analyses also indicate that different magnetic connectivity domains of the quadrupolar configuration become unstable
during each flare, so that magnetic reconnection proceeds differently in both events. 相似文献
20.
Relationship between Rotating Sunspots and Flares 总被引：2，自引：0，他引：2
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. 相似文献