Major solar plasma disturbances are subjected to Lomb-Scargle periodogram and wavelet analysis to determine the occurrence frequency.These disruptions include interplanetary coronal mass ejection,sudden storm commence...Major solar plasma disturbances are subjected to Lomb-Scargle periodogram and wavelet analysis to determine the occurrence frequency.These disruptions include interplanetary coronal mass ejection,sudden storm commencement,high-speed streams,corotating interaction regions,interplanetary shocks and Forbush decreases.We included information on all of the aforementioned solar disturbances for the last six solar cycles,from 1965 to 2023,for this study.Our findings reveal some intriguing and noteworthy results that clearly distinguish between even and odd-numbered solar cycles.The study suggests that the Sun behaves differently in odd and even-numbered solar cycles as it comes from the massive solar eruptions.During even-numbered solar cycles,variations with a period of∼44 days are prominently observed in addition to solar rotation(∼27 days)and extended solar(∼36 days)rotation.However,in addition to solar rotation,prolonged solar rotation,and periods of around 44 days,we also detect a number of intermittent changes with nearly comparable amplitude during the oddnumbered solar cycles.The findings also demonstrate that,in contrast to odd-numbered solar cycles,the emissions rate of these disruptions is more distinct and predictable during even-numbered solar cycles.展开更多
We present an analysis of the magnetic mechanism of an X6.4-class confined flare in NOAA Active Region(AR)13590 on 2024 February 22.Despite a pre-existing magnetic flux rope(MFR)embedded within a null-point topology,t...We present an analysis of the magnetic mechanism of an X6.4-class confined flare in NOAA Active Region(AR)13590 on 2024 February 22.Despite a pre-existing magnetic flux rope(MFR)embedded within a null-point topology,the flare produced only a localized jet without an associated coronal mass ejection.Using data from the Solar Dynamics Observatory and nonlinear force-free field extrapolations,we traced the formation and evolution of the MFR,which developed under photospheric shearing motions but remained weakly twisted(with twist number being lower than 1.3)and below the thresholds for kink instability.Meanwhile,the MFR is located at heights where the decay index(n≤1.0)of the overlying field was insufficient to trigger torus instability.Furthermore,we calculated two important parameters measuring the non-potentiality of the AR,one is the ratio of the free energy to the potential-field energy,and the other is the ratio of the non-potential helicity to the square of the magnetic flux.Both the two parameters were significantly lower than critical values for eruptive flares.These factors,combined with the stabilizing influence of the strong overlying field,confined the MFR and limited the eruption to a jet.Our findings highlight the importance of both local magnetic properties and global energy constraints in determining the eruptive potential of solar flares.展开更多
Decameter-hectometric(DH)Type Ⅱ bursts,arising from coronal mass ejection(CME)-driven shock waves,are crucial for understanding solar-terrestrial interactions and space weather forecasting.This study provides a compr...Decameter-hectometric(DH)Type Ⅱ bursts,arising from coronal mass ejection(CME)-driven shock waves,are crucial for understanding solar-terrestrial interactions and space weather forecasting.This study provides a comprehensive statistical analysis of CMEs associated with DH type Ⅱ solar radio bursts during Solar Cycle 24(2009–2019),utilizing data from the Wind/WAVES,Solar TErrestrial RElations Observatory/SWAVES,and Solar and Heliospheric Observatory/LASCO catalogs.Analyzing 180 events,we report key spectral and kinematic properties,including a mean CME speed of(1058±531)km s^(−1) and a mean width of(288.39±99.3),with 62%classified as halo CMEs.About 12%of the total CMEs are accelerated,58%of them are decelerated,and 30%of them are constant.Similarly,CMEs having a speed≤800 km s^(−1) are constant,and those with speed≥800 km s^(−1) are decelerated.DH type Ⅱ bursts displayed a mean starting frequency of(12,169.72±4939)kHz,ending frequency of(2152.69±3022.07)kHz,bandwidth of(10,017±5353)kHz,and an average duration of(345.62±453)minutes.A power-law relationship was established between the drift rate(df/dt)and burst duration(D),characterized by df/dt=2749.07·D^(−0.88),highlighting the inverse dependence of drift rate on burst longevity.This suggests a dynamic interplay between shock parameters and the ambient solar corona.The findings underscore the persistent and robust spectral coverage of CME-driven shocks,offering new insights into their evolution and impact on the heliospheric environment.展开更多
The polar magnetic fields of the Sun play an important role in governing solar activity and powering fast solar wind.However,because our view of the Sun is limited in the ecliptic plane,the polar regions remain largel...The polar magnetic fields of the Sun play an important role in governing solar activity and powering fast solar wind.However,because our view of the Sun is limited in the ecliptic plane,the polar regions remain largely uncharted.Using the high spatial resolution and polarimetric precision vector magnetograms observed by Hinode from 2012 to 2021,we investigate the long-term variation of the magnetic fields in polar caps at different latitudes.The Hinode magnetic measurements show that the polarity reversal processes in the north and south polar caps are non-simultaneous.The variation of the averaged radial magnetic flux density reveals that,in each polar cap,the polarity reversal is completed successively from the 70°latitude to the pole,reflecting a poleward magnetic flux migration therein.These results clarify the polar magnetic polarity reversal process at different latitudes.展开更多
Coronal magnetic fields evolve quasi-statically over long timescales and dynamically over short timescales.As of now there exist no regular measurements of coronal magnetic fields,and therefore generating the coronal ...Coronal magnetic fields evolve quasi-statically over long timescales and dynamically over short timescales.As of now there exist no regular measurements of coronal magnetic fields,and therefore generating the coronal magnetic field evolution using observations of the magnetic field at the photosphere is a fundamental requirement to understanding the origin of transient phenomena from solar active regions(ARs).Using the magneto-friction(MF)approach,we aim to simulate the coronal field evolution in the solar AR 11429.The MF method is implemented in the open source PENCIL CODE along with a driver module to drive the initial field with different boundary conditions prescribed from observed vector magnetic fields at the photosphere.In order to work with vector potential and the observations,we prescribe three types of bottom boundary drivers with varying free-magnetic energy.The MF simulation reproduces the magnetic structure,which better matches the sigmoidal morphology exhibited by Atmospheric Imaging Assembly(AIA)images at the pre-eruptive time.We found that the already sheared field further driven by the sheared magnetic field will maintain and further build the highly sheared coronal magnetic configuration,as seen in AR 11429.Data-driven MF simulation is a viable tool to generate the coronal magnetic field evolution,capturing the formation of the twisted flux rope and its eruption.展开更多
Solar active regions(ARs)are formed by the emergence of current-carrying magnetic flux tubes from below the photosphere.Although for an isolated flux tube the direct and return currents flowing along the tube should b...Solar active regions(ARs)are formed by the emergence of current-carrying magnetic flux tubes from below the photosphere.Although for an isolated flux tube the direct and return currents flowing along the tube should balance with each other,it remains controversial whether such a neutralization of currents is also maintained during the emergence process.Here we present a systematic survey of the degrees of the current neutralization in a large sample of flux-emerging ARs which appeared on the solar disk around the central meridian from 2010 to 2022.The vector magnetograms taken by Helioseismic and Magnetic Imager onboard Solar Dynamic Observatory are employed to calculate the distributions of the vertical current density at the photosphere.Focusing on the main phase of flux emergence,i.e.,the phase in which the total unsigned magnetic flux is continuously increased,we statistically examined the ratios of direct to return currents in all the ARs.Such a large-sample statistical study suggests that most of the ARs were born with currents close to neutralization.The degree of current neutralization seems to be not affected by the active-region size,the active-region growing rate,and the total unsigned current.The only correlation of significance as found is that the stronger the magnetic field nonpotentiality is,the further the AR deviates from current neutrality,which supports previous event studies that eruption-productive ARs often have non-neutralized currents.展开更多
In this present study,we have analyzed different types of X-ray solar flares(C,M,and X classes)coming out from different classes of sunspot groups(SSGs).The data which we have taken under this study cover the duration...In this present study,we have analyzed different types of X-ray solar flares(C,M,and X classes)coming out from different classes of sunspot groups(SSGs).The data which we have taken under this study cover the duration of 24 yr from 1996 to 2019.During this,we observed a total of 15015 flares(8417 in SC-23 and 6598 in SC-24)emitted from a total of 33780 active regions(21746 in SC-23 and 12034 in SC-24)with sunspot only.We defined the flaring potential or flare-production potential as the ratio of the total number of flares produced from a particular type of SSG to the total number of the same-class SSGs observed on the solar surface.Here we studied yearly changes in the flaring potential of different McIntosh class groups of sunspots in different phases of SC-23 and 24.In addition,we investigated yearly variations in the potential of producing flares by different SSGs(A,B,C,D,E,F,and H)during different phases(ascending,maximum,descending,and minimum)of SC-23 and 24.These are our findings:(1)D,E,and F SSGs have the potential of producing flares≥8 times greater than A,B,C and H SSGs;(2)The larger and more complex D,E,and F SSGs produced nearly 80%of flares in SC-23 and 24;(3)The A,B,C and H SSGs,which are smaller and simpler,produced only 20%of flares in SC-23 and 24;(4)The biggest and most complex SSGs of F-class have flaring potential 1.996 and 3.443 per SSG in SC-23 and 24,respectively.(5)The potential for producing flares in each SSG is higher in SC-24 than in SC-23,although SC-24 is a weaker cycle than SC-23.(6)The alterations in the number of flares(C+M+X)show different time profiles than the alterations in sunspot numbers during SC-23 and 24,with several peaks.(7)The SSGs of C,D,E,and H-class have the highest flaring potential in the descending phase of both SC-23 and 24.(8)F-class SSGs have the highest flaring potential in the descending phase of SC-23 but also in the maximum phase of SC-24.展开更多
The Advanced Space-based Solar Observatory(ASO-S)is a mission proposed for the 25 th solar maximum by the Chinese solar community.The scientific objectives are to study the relationships between the solar magnetic fie...The Advanced Space-based Solar Observatory(ASO-S)is a mission proposed for the 25 th solar maximum by the Chinese solar community.The scientific objectives are to study the relationships between the solar magnetic field,solar flares and coronal mass ejections(CMEs).Three payloads are deployed:the Full-disk vector Magneto Graph(FMG),the Lyman-αSolar Telescope(LST)and the Hard X-ray Imager(HXI).ASO-S will perform the first simultaneous observations of the photospheric vector magnetic field,non-thermal imaging of solar flares,and the initiation and early propagation of CMEs on a single platform.ASO-S is scheduled to be launched into a 720 km Sun-synchronous orbit in 2022.This paper presents an overview of the mission till the end of Phase-B and the beginning of Phase-C.展开更多
The Full-disk vector Magneto Graph(FMG)instrument will carry out polarization observations at one wavelength position of the Fe I 5324.179?spectral line.This paper describes how to choose this single wavelength positi...The Full-disk vector Magneto Graph(FMG)instrument will carry out polarization observations at one wavelength position of the Fe I 5324.179?spectral line.This paper describes how to choose this single wavelength position,the relevant data-processing and the magnetic field calibrations based on the measured polarization signals at one single wavelength position.It is found that solar radial Doppler velocity,which can cause the spectral line to shift,is a disadvantageous factor for the linear calibration at one wavelength position.Observations at two symmetric wavelength positions may significantly reduce the wavelength shift effect(~75%),but simulations show that such polarization signals located at the solar limbs(e.g.,beyond the longitude range of±30°)are not free from the effect completely.In future work,we plan to apply machine learning techniques to calibrate vector magnetic fields,or employ full Stokes parameter profile inversion techniques to obtain accurate vector magnetic fields,in order to complement the linear calibration at the single wavelength position.展开更多
A filament is a cool, dense structure suspended in the solar corona. The eruption of a filament is often associated with a coronal mass ejection(CME), which has an adverse effect on space weather. Hence,research on fi...A filament is a cool, dense structure suspended in the solar corona. The eruption of a filament is often associated with a coronal mass ejection(CME), which has an adverse effect on space weather. Hence,research on filaments has attracted much attention in the recent past. The tilt angle of active region(AR)magnetic bipoles is a crucial parameter in the context of the solar dynamo, which governs the conversion efficiency of the toroidal magnetic field to poloidal magnetic field. Filaments always form over polarity inversion lines(PILs), so the study of tilt angles for these filaments can provide valuable information about generation of a magnetic field in the Sun. We investigate the tilt angles of filaments and other properties using McIntosh Archive data. We fit a straight line to each filament to estimate its tilt angle. We examine the variation of mean tilt angle with time. The latitude distribution of positive tilt angle filaments and negative tilt angle filaments reveals that there is a dominance of positive tilt angle filaments in the southern hemisphere and negative tilt angle filaments dominate in the northern hemisphere. We study the variation of the mean tilt angle for low and high latitudes separately. Investigations of temporal variation with filament number indicate that total filament number and low latitude filament number vary cyclically, in phase with the solar cycle. There are fewer filaments at high latitudes and they also show a cyclic pattern in temporal variation. We also study the north-south asymmetry of filaments with different latitude criteria.展开更多
Solar flares and coronal mass ejections(CMEs)are thought to be the most powerful events on the Sun.They can release energy as high as~10^(32)erg in tens of minutes,and also can release solar energetic particles(SEPs)i...Solar flares and coronal mass ejections(CMEs)are thought to be the most powerful events on the Sun.They can release energy as high as~10^(32)erg in tens of minutes,and also can release solar energetic particles(SEPs)into interplanetary space.We explore global energy budgets of solar major eruptions that occurred on 2017 September 6,including the energy partition of a powerful solar flare,and the energy budget of the accompanying CME and SEPs.In the wavelength range shortward of~222 nm,a major contribution of the flare radiated energy is in the soft X-ray(SXR)0.1-7 nm domain.The flare energy radiated at wavelengths of Lyαand mid-ultraviolet is larger than that radiated in the extreme ultraviolet wavelengths,but it is much less than that radiated in the SxR waveband.The total flare radiated energy could be comparable to the thermal and nonthermal energies.The energies carried by the major flare and its accompanying CME are roughly equal,and they are both powered by the magnetic free energy in the NOAA AR 12673.Moreover,the CME is efficient in accelerating SEPs,and the prompt component(whether it comes from the solar flare or the CME)contributes only a negligible fraction.展开更多
A section of an S-shaped filament underwent an eruption in a sigmoidal active region （AR 8027） with S-shaped coronal structure, which was clearly driven by a bipole emerging below the NW end of the filament. The bip...A section of an S-shaped filament underwent an eruption in a sigmoidal active region （AR 8027） with S-shaped coronal structure, which was clearly driven by a bipole emerging below the NW end of the filament. The bipole with two separating poles showed typical characteristics of emerging flux region （EFR） and its axis rotated counterclockwise. Two canceiling magnetic features （CMFs） were formed between the two poles and adjacent flux with opposite polarity and substantial flux cancellation occurred in them. Along with the bipole emergence the filament was strongly disturbed. Just before the filament eruption, two X-ray loops overlying the filament brightened, an axial X-ray structure and then a cusp structure appeared. During the eruption first the whole filament rose and then its SE end broke away from the chromosphere, while its NW end remained stationary. Helical structure and motion were observed in the filament body and downward mass motion in the two ends. After the eruption, a major part of the filament remained and slowly returned to quiescence, and an X-ray arcade and an axial structure formed. These observations suggest that the eruption resuited from the interaction between the bipole and the overlying loops. We provide evidence that steady photospheric reconnection between their footprints took place in the two CMFs during the bipole emergence.展开更多
Learning the mapping of magnetograms and EUV images is important for understanding the solar eruption mechanism and space weather forecasting.Previous works are mainly based on the pix2pix model for full-disk magnetog...Learning the mapping of magnetograms and EUV images is important for understanding the solar eruption mechanism and space weather forecasting.Previous works are mainly based on the pix2pix model for full-disk magnetograms generation and obtain good performance.However,in general,we are more concerned with the magnetic field distribution in the active regions where various solar storms such as the solar flare and coronal mass ejection happen.In this paper,we fuse the self-attention mechanism with the pix2pix model which allows more computation resource and greater weight for strong magnetic regions.In addition,the attention features are concatenated by the Residual Hadamard Production(RHP) with the abstracted features after the encoder.We named our model as RHP-attention pix2pix.From the experiments,we can find that the proposed model can generate magnetograms with finer strong magnetic structures,such as sunspots.In addition,the polarity distribution of generated magnetograms at strong magnetic regions is more consistent with observed ones.展开更多
Magnetic fields play a key role in driving a broad range of dynamic phenomena in the atmospheres of the Sun and other stars.Routine and accurate measurements of the magnetic fields at all the atmospheric layers are of...Magnetic fields play a key role in driving a broad range of dynamic phenomena in the atmospheres of the Sun and other stars.Routine and accurate measurements of the magnetic fields at all the atmospheric layers are of critical importance to understand these magnetic activities,but in the solar and stellar coronae such a measurement is still a challenge due to the weak field strength and the high temperature.Recently,a magnetic-field-induced transition(MIT)of Fe X at 257.26A has been proposed for the magnetic field measurements in the solar and stellar coronae.In this review,we present an overview of recent progresses in the application of this method in astrophysics.We start by introducing the theory underlying the MIT method and reviewing the existing atomic data critical for the spectral modeling of Fe X lines.We also discuss the laboratory measurements that verify the potential capability of the MIT technique as a probe for diagnosing the plasma magnetic fields.We then continue by investigating the suitability and accuracy of solar and stellar coronal magnetic field measurements based on the MIT method through forward modeling.Furthermore,we discuss the application of the MIT method to the existing spectroscopic observations obtained by the Extreme-ultraviolet Imaging Spectrometer onboard Hinode.This novel technique provides a possible way for routine measurements of the magnetic fields in the solar and stellar coronae,but still requires further efforts to improve its accuracy.Finally,the challenges and prospects for future research on this topic are discussed.展开更多
We report detailed observation of the“herringbone”of a Type II solar radio burst that occurred on 2010 November 3rd.Data from the Space Weather Prediction Center,National Oceanic and Atmospheric Administration,e-CAL...We report detailed observation of the“herringbone”of a Type II solar radio burst that occurred on 2010 November 3rd.Data from the Space Weather Prediction Center,National Oceanic and Atmospheric Administration,e-CALLISTO,and Nan?ay Radio Heliograph are analyzed.We determine the brightness temperature and degree of circular polarization of the“herringbone”burst.Correlations between the physical parameters and the“herringbone”are examined.Based on the relationship,this is the first study that suggested this“herringbone”was generated through fundamental plasma.展开更多
Accurate measurement of magnetic fields is very important for understanding the formation and evolution of solar magnetic fields.Currently,there are two types of solar magnetic field measurement instruments:filter-bas...Accurate measurement of magnetic fields is very important for understanding the formation and evolution of solar magnetic fields.Currently,there are two types of solar magnetic field measurement instruments:filter-based magnetographs and Stokes polarimeters.The former gives high temporal resolution magnetograms and the latter provides more accurate measurements of magnetic fields.Calibrating the magnetograms obtained by filter-based magnetographs with those obtained by Stokes polarimeters is a good way to combine the advantages of the two types.Our previous studies have shown that,compared to the magnetograms obtained by the Spectro-Polarimeter(SP)on board Hinode,those magnetograms obtained by both the filter-based Solar Magnetic Field Telescope(SMFT)of the Huairou Solar Observing Station and by the filter-based Michelson Doppler Imager(MDI)aboard SOHO have underestimated the flux densities in their magnetograms and systematic center-to-limb variations present in the magnetograms of both instruments.Here,using a sample of 75 vector magnetograms of stable alpha sunspots,we compare the vector magnetograms obtained by the Helioseismic and Magnetic Imager(HMI)aboard Solar Dynamics Observatory(SDO)with co-temporal vector magnetograms acquired by SP/Hinode.Our analysis shows that both the longitudinal and transverse flux densities in the HMI/SDO magnetograms are very close to those in the SP/Hinode magnetograms and the systematic center-to-limb variations in the HMI/SDO magnetograms are very minor.Our study suggests that using a filter-based magnetograph to construct a low spectral resolution Stokes profile,as done by HMI/SDO,can largely remove the disadvantages of the filter-type measurements and yet still possess the advantage of high temporal resolution.展开更多
We statistically study the properties of emerging flux regions(EFRs)and response of the upper solar atmosphere to the flux emergence using data from the Helioseismic and Magnetic Imager and the Atmospheric Imaging Ass...We statistically study the properties of emerging flux regions(EFRs)and response of the upper solar atmosphere to the flux emergence using data from the Helioseismic and Magnetic Imager and the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory.Parameters including total emerged flux,flux growth rate,maximum area,duration of the emergence and separation speed of the opposite polarities are adopted to delineate the properties of EFRs.The response of the upper atmosphere is addressed by the response of the atmosphere at different wavelengths(and thus at different temperatures).According to our results,the total emerged fluxes are in the range of(0.44-11.2)×1019 Mx while the maximum area ranges from 17 to 182 arcsec2.The durations of the emergence are between 1 and 12 h,which are positively correlated to both the total emerged flux and the maximum area.The maximum distances between the opposite polarities are 7-25 arcsec and are also positively correlated to the duration.The separation speeds are from 0.05 to 1.08 km s-1,negatively correlated to the duration.The derived flux growth rates are(0.1-1.3)×1019 Mx h-1,which are positively correlated to the total emerging flux.The upper atmosphere first responds to the flux emergence in the 1600Achromospheric line,and then tens to hundreds of seconds later,in coronal lines,such as the 171(T=105.8 K)and 211(T=106.3 K)lines almost simultaneously,suggesting the successive heating of the atmosphere from the chromosphere to the corona.展开更多
There are only a few observations published so far that show the initiation of a coronal mass ejection (CME) and illustrate the magnetic changes in the surface origin of a CME. Any attempt to connect a CME with its l...There are only a few observations published so far that show the initiation of a coronal mass ejection (CME) and illustrate the magnetic changes in the surface origin of a CME. Any attempt to connect a CME with its local solar activities is meaningful. In this paper we present a clear instance of a halo CME initiation. A careful analysis of magnetograms shows that the only obvious magnetic changes in the surface region of the CME is a magnetic flux cancellation underneath a quiescent filament. The early disturbance was seen as the slow upward motion in segments of the quiescent filament. Four hours later, the filament was accelerated to about 50 km s-1 and erupted. While a small part of the material in the filament was ejected into the upper corona, most of the mass was transported to a nearby region. About forty minutes later, the transported mass was also ejected partially to the upper corona. The eruption of the filament triggered a two-ribbon flare, with post-flare loops connecting the flare ribbons. A halo CME, which is inferred to be associated with the eruptive filament, was observed from LASCO/C2 and C3. The halo CME contained two CME events, each event corresponded to a partial mass ejection of the filament. We suggest that the magnetic reconnection at the lower atmosphere is responsible for the filament eruption and the halo CME.展开更多
文摘Major solar plasma disturbances are subjected to Lomb-Scargle periodogram and wavelet analysis to determine the occurrence frequency.These disruptions include interplanetary coronal mass ejection,sudden storm commencement,high-speed streams,corotating interaction regions,interplanetary shocks and Forbush decreases.We included information on all of the aforementioned solar disturbances for the last six solar cycles,from 1965 to 2023,for this study.Our findings reveal some intriguing and noteworthy results that clearly distinguish between even and odd-numbered solar cycles.The study suggests that the Sun behaves differently in odd and even-numbered solar cycles as it comes from the massive solar eruptions.During even-numbered solar cycles,variations with a period of∼44 days are prominently observed in addition to solar rotation(∼27 days)and extended solar(∼36 days)rotation.However,in addition to solar rotation,prolonged solar rotation,and periods of around 44 days,we also detect a number of intermittent changes with nearly comparable amplitude during the oddnumbered solar cycles.The findings also demonstrate that,in contrast to odd-numbered solar cycles,the emissions rate of these disruptions is more distinct and predictable during even-numbered solar cycles.
基金supported by Guangdong Basic and Applied Basic Research Foundation(2025A1515011353)the Specialized Research Fund for State Key Laboratory of Solar Activity and Space Weather.
文摘We present an analysis of the magnetic mechanism of an X6.4-class confined flare in NOAA Active Region(AR)13590 on 2024 February 22.Despite a pre-existing magnetic flux rope(MFR)embedded within a null-point topology,the flare produced only a localized jet without an associated coronal mass ejection.Using data from the Solar Dynamics Observatory and nonlinear force-free field extrapolations,we traced the formation and evolution of the MFR,which developed under photospheric shearing motions but remained weakly twisted(with twist number being lower than 1.3)and below the thresholds for kink instability.Meanwhile,the MFR is located at heights where the decay index(n≤1.0)of the overlying field was insufficient to trigger torus instability.Furthermore,we calculated two important parameters measuring the non-potentiality of the AR,one is the ratio of the free energy to the potential-field energy,and the other is the ratio of the non-potential helicity to the square of the magnetic flux.Both the two parameters were significantly lower than critical values for eruptive flares.These factors,combined with the stabilizing influence of the strong overlying field,confined the MFR and limited the eruption to a jet.Our findings highlight the importance of both local magnetic properties and global energy constraints in determining the eruptive potential of solar flares.
基金supported by the National Key R&D Program of China(2021YFA1600500 and 2021YFA1600503)sponsored by the CAS-TWAS President Fellowship Programpartially supported by the Tianchi Talent Program of the Xinjiang Uygur Autonomous Region of China.
文摘Decameter-hectometric(DH)Type Ⅱ bursts,arising from coronal mass ejection(CME)-driven shock waves,are crucial for understanding solar-terrestrial interactions and space weather forecasting.This study provides a comprehensive statistical analysis of CMEs associated with DH type Ⅱ solar radio bursts during Solar Cycle 24(2009–2019),utilizing data from the Wind/WAVES,Solar TErrestrial RElations Observatory/SWAVES,and Solar and Heliospheric Observatory/LASCO catalogs.Analyzing 180 events,we report key spectral and kinematic properties,including a mean CME speed of(1058±531)km s^(−1) and a mean width of(288.39±99.3),with 62%classified as halo CMEs.About 12%of the total CMEs are accelerated,58%of them are decelerated,and 30%of them are constant.Similarly,CMEs having a speed≤800 km s^(−1) are constant,and those with speed≥800 km s^(−1) are decelerated.DH type Ⅱ bursts displayed a mean starting frequency of(12,169.72±4939)kHz,ending frequency of(2152.69±3022.07)kHz,bandwidth of(10,017±5353)kHz,and an average duration of(345.62±453)minutes.A power-law relationship was established between the drift rate(df/dt)and burst duration(D),characterized by df/dt=2749.07·D^(−0.88),highlighting the inverse dependence of drift rate on burst longevity.This suggests a dynamic interplay between shock parameters and the ambient solar corona.The findings underscore the persistent and robust spectral coverage of CME-driven shocks,offering new insights into their evolution and impact on the heliospheric environment.
基金supported by the National Key R&D Programs of China(2019YFA0405000,2022YFF0503800,2022YFF0503000)the Strategic Priority Research Programs of the Chinese Academy of Sciences(XDB0560000,XDB41000000)+1 种基金the National Natural Science Foundations of China(NSFC,Grant Nos.12173005,12273060,12350004,12273061,12222306,and 12073001)the Youth Innovation Promotion Association CAS,and Yunnan Academician Workstation of Wang Jingxiu(No.202005AF150025)。
文摘The polar magnetic fields of the Sun play an important role in governing solar activity and powering fast solar wind.However,because our view of the Sun is limited in the ecliptic plane,the polar regions remain largely uncharted.Using the high spatial resolution and polarimetric precision vector magnetograms observed by Hinode from 2012 to 2021,we investigate the long-term variation of the magnetic fields in polar caps at different latitudes.The Hinode magnetic measurements show that the polarity reversal processes in the north and south polar caps are non-simultaneous.The variation of the averaged radial magnetic flux density reveals that,in each polar cap,the polarity reversal is completed successively from the 70°latitude to the pole,reflecting a poleward magnetic flux migration therein.These results clarify the polar magnetic polarity reversal process at different latitudes.
基金the support from DST through Startup Research Grantfunding from the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation program(Project Uni SDyn,grant agreement No.818665)(JW)。
文摘Coronal magnetic fields evolve quasi-statically over long timescales and dynamically over short timescales.As of now there exist no regular measurements of coronal magnetic fields,and therefore generating the coronal magnetic field evolution using observations of the magnetic field at the photosphere is a fundamental requirement to understanding the origin of transient phenomena from solar active regions(ARs).Using the magneto-friction(MF)approach,we aim to simulate the coronal field evolution in the solar AR 11429.The MF method is implemented in the open source PENCIL CODE along with a driver module to drive the initial field with different boundary conditions prescribed from observed vector magnetic fields at the photosphere.In order to work with vector potential and the observations,we prescribe three types of bottom boundary drivers with varying free-magnetic energy.The MF simulation reproduces the magnetic structure,which better matches the sigmoidal morphology exhibited by Atmospheric Imaging Assembly(AIA)images at the pre-eruptive time.We found that the already sheared field further driven by the sheared magnetic field will maintain and further build the highly sheared coronal magnetic configuration,as seen in AR 11429.Data-driven MF simulation is a viable tool to generate the coronal magnetic field evolution,capturing the formation of the twisted flux rope and its eruption.
基金supported by the National Natural Science Foundation of China(NSFC)U2031108Yunnan Key Laboratory of Solar Physics and Space Science under the number YNSPCC202213。
文摘Solar active regions(ARs)are formed by the emergence of current-carrying magnetic flux tubes from below the photosphere.Although for an isolated flux tube the direct and return currents flowing along the tube should balance with each other,it remains controversial whether such a neutralization of currents is also maintained during the emergence process.Here we present a systematic survey of the degrees of the current neutralization in a large sample of flux-emerging ARs which appeared on the solar disk around the central meridian from 2010 to 2022.The vector magnetograms taken by Helioseismic and Magnetic Imager onboard Solar Dynamic Observatory are employed to calculate the distributions of the vertical current density at the photosphere.Focusing on the main phase of flux emergence,i.e.,the phase in which the total unsigned magnetic flux is continuously increased,we statistically examined the ratios of direct to return currents in all the ARs.Such a large-sample statistical study suggests that most of the ARs were born with currents close to neutralization.The degree of current neutralization seems to be not affected by the active-region size,the active-region growing rate,and the total unsigned current.The only correlation of significance as found is that the stronger the magnetic field nonpotentiality is,the further the AR deviates from current neutrality,which supports previous event studies that eruption-productive ARs often have non-neutralized currents.
基金partially supported by the Institute of Eminence(Io E)Program(Scheme No:6031)of BHU,Varanasi。
文摘In this present study,we have analyzed different types of X-ray solar flares(C,M,and X classes)coming out from different classes of sunspot groups(SSGs).The data which we have taken under this study cover the duration of 24 yr from 1996 to 2019.During this,we observed a total of 15015 flares(8417 in SC-23 and 6598 in SC-24)emitted from a total of 33780 active regions(21746 in SC-23 and 12034 in SC-24)with sunspot only.We defined the flaring potential or flare-production potential as the ratio of the total number of flares produced from a particular type of SSG to the total number of the same-class SSGs observed on the solar surface.Here we studied yearly changes in the flaring potential of different McIntosh class groups of sunspots in different phases of SC-23 and 24.In addition,we investigated yearly variations in the potential of producing flares by different SSGs(A,B,C,D,E,F,and H)during different phases(ascending,maximum,descending,and minimum)of SC-23 and 24.These are our findings:(1)D,E,and F SSGs have the potential of producing flares≥8 times greater than A,B,C and H SSGs;(2)The larger and more complex D,E,and F SSGs produced nearly 80%of flares in SC-23 and 24;(3)The A,B,C and H SSGs,which are smaller and simpler,produced only 20%of flares in SC-23 and 24;(4)The biggest and most complex SSGs of F-class have flaring potential 1.996 and 3.443 per SSG in SC-23 and 24,respectively.(5)The potential for producing flares in each SSG is higher in SC-24 than in SC-23,although SC-24 is a weaker cycle than SC-23.(6)The alterations in the number of flares(C+M+X)show different time profiles than the alterations in sunspot numbers during SC-23 and 24,with several peaks.(7)The SSGs of C,D,E,and H-class have the highest flaring potential in the descending phase of both SC-23 and 24.(8)F-class SSGs have the highest flaring potential in the descending phase of SC-23 but also in the maximum phase of SC-24.
基金supported by the Strategic Priority Research Program on Space Science, Chinese Academy of Sciences (Grant Nos. XDA15320100, XDA15320102, XDA15320103, XDA15320104, XDA15320300 and XDA15052200)supported by the National Natural Science Foundation of China (Grant Nos. 11427803, U1731241, U1631242 and 11820101002)
文摘The Advanced Space-based Solar Observatory(ASO-S)is a mission proposed for the 25 th solar maximum by the Chinese solar community.The scientific objectives are to study the relationships between the solar magnetic field,solar flares and coronal mass ejections(CMEs).Three payloads are deployed:the Full-disk vector Magneto Graph(FMG),the Lyman-αSolar Telescope(LST)and the Hard X-ray Imager(HXI).ASO-S will perform the first simultaneous observations of the photospheric vector magnetic field,non-thermal imaging of solar flares,and the initiation and early propagation of CMEs on a single platform.ASO-S is scheduled to be launched into a 720 km Sun-synchronous orbit in 2022.This paper presents an overview of the mission till the end of Phase-B and the beginning of Phase-C.
基金supported by the Strategic Priority Research Program on Space Science, the Chinese Academy of Sciences (Grant Nos. XDA15320302, XDA15052200 and XDA15320102)the National Natural Science Foundation of China (Grant Nos. 11773038, 11703042, U1731241, 11427901, 11427803, 11473039 and U1831107)the 13th Fiveyear Informatization Plan of the Chinese Academy of Sciences (Grant No. XXH13505-04)
文摘The Full-disk vector Magneto Graph(FMG)instrument will carry out polarization observations at one wavelength position of the Fe I 5324.179?spectral line.This paper describes how to choose this single wavelength position,the relevant data-processing and the magnetic field calibrations based on the measured polarization signals at one single wavelength position.It is found that solar radial Doppler velocity,which can cause the spectral line to shift,is a disadvantageous factor for the linear calibration at one wavelength position.Observations at two symmetric wavelength positions may significantly reduce the wavelength shift effect(~75%),but simulations show that such polarization signals located at the solar limbs(e.g.,beyond the longitude range of±30°)are not free from the effect completely.In future work,we plan to apply machine learning techniques to calibrate vector magnetic fields,or employ full Stokes parameter profile inversion techniques to obtain accurate vector magnetic fields,in order to complement the linear calibration at the single wavelength position.
基金the team at the McIntosh Archive project (a Boston College/NOAA/NCAR collaboration, funded by the NSF), based at NOAA National Centers for Environmental Information, for creating a digital archive of McIntosh Carrington maps and making it available online. R.M
文摘A filament is a cool, dense structure suspended in the solar corona. The eruption of a filament is often associated with a coronal mass ejection(CME), which has an adverse effect on space weather. Hence,research on filaments has attracted much attention in the recent past. The tilt angle of active region(AR)magnetic bipoles is a crucial parameter in the context of the solar dynamo, which governs the conversion efficiency of the toroidal magnetic field to poloidal magnetic field. Filaments always form over polarity inversion lines(PILs), so the study of tilt angles for these filaments can provide valuable information about generation of a magnetic field in the Sun. We investigate the tilt angles of filaments and other properties using McIntosh Archive data. We fit a straight line to each filament to estimate its tilt angle. We examine the variation of mean tilt angle with time. The latitude distribution of positive tilt angle filaments and negative tilt angle filaments reveals that there is a dominance of positive tilt angle filaments in the southern hemisphere and negative tilt angle filaments dominate in the northern hemisphere. We study the variation of the mean tilt angle for low and high latitudes separately. Investigations of temporal variation with filament number indicate that total filament number and low latitude filament number vary cyclically, in phase with the solar cycle. There are fewer filaments at high latitudes and they also show a cyclic pattern in temporal variation. We also study the north-south asymmetry of filaments with different latitude criteria.
基金funded by the National Key R&D Program of China 2022YFF0503002(2022YFF0503000)the National Natural Science Foundation of China(NSFC,Grant Nos.11973092,12073081,12003064,12103090 and U1938102)+6 种基金the Strategic Priority Research Program on Space Science,CAS,grant Nos.XDA15052200 and XDA15320301supported by the Specialized Research Fund for State Key LaboratoriesLYRA is a project of the Centre Spatial de Liege,the Physikalisch-Meteorologisches Observatorium Davos and the Royal Observatory of Belgium funded by the Belgian Federal Science Policy Office(BELSPO)by the Swiss Bundesamt für Bildung und WissenschaftPart of this work was performed in the framework of the SERPENTINE project,which has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No.101004159support by the Turku Collegium for Science,Medicine and Technology of the University of Turku,Finlandsupport from the Belgian Federal Science Policy Office(BELSPO)in the framework of the ESA-PRODEX program,grant No.4000134474.
文摘Solar flares and coronal mass ejections(CMEs)are thought to be the most powerful events on the Sun.They can release energy as high as~10^(32)erg in tens of minutes,and also can release solar energetic particles(SEPs)into interplanetary space.We explore global energy budgets of solar major eruptions that occurred on 2017 September 6,including the energy partition of a powerful solar flare,and the energy budget of the accompanying CME and SEPs.In the wavelength range shortward of~222 nm,a major contribution of the flare radiated energy is in the soft X-ray(SXR)0.1-7 nm domain.The flare energy radiated at wavelengths of Lyαand mid-ultraviolet is larger than that radiated in the extreme ultraviolet wavelengths,but it is much less than that radiated in the SxR waveband.The total flare radiated energy could be comparable to the thermal and nonthermal energies.The energies carried by the major flare and its accompanying CME are roughly equal,and they are both powered by the magnetic free energy in the NOAA AR 12673.Moreover,the CME is efficient in accelerating SEPs,and the prompt component(whether it comes from the solar flare or the CME)contributes only a negligible fraction.
基金Supported by the National Natural Science Foundation of China.
文摘A section of an S-shaped filament underwent an eruption in a sigmoidal active region （AR 8027） with S-shaped coronal structure, which was clearly driven by a bipole emerging below the NW end of the filament. The bipole with two separating poles showed typical characteristics of emerging flux region （EFR） and its axis rotated counterclockwise. Two canceiling magnetic features （CMFs） were formed between the two poles and adjacent flux with opposite polarity and substantial flux cancellation occurred in them. Along with the bipole emergence the filament was strongly disturbed. Just before the filament eruption, two X-ray loops overlying the filament brightened, an axial X-ray structure and then a cusp structure appeared. During the eruption first the whole filament rose and then its SE end broke away from the chromosphere, while its NW end remained stationary. Helical structure and motion were observed in the filament body and downward mass motion in the two ends. After the eruption, a major part of the filament remained and slowly returned to quiescence, and an X-ray arcade and an axial structure formed. These observations suggest that the eruption resuited from the interaction between the bipole and the overlying loops. We provide evidence that steady photospheric reconnection between their footprints took place in the two CMFs during the bipole emergence.
基金funded by the National Key R&D Program of China(Nos.2021YFA1600504 and 2022YFE0133700)the National Natural Science Foundation of China(NSFC)(Nos.11790305,11963003,12273007 and 61902371)。
文摘Learning the mapping of magnetograms and EUV images is important for understanding the solar eruption mechanism and space weather forecasting.Previous works are mainly based on the pix2pix model for full-disk magnetograms generation and obtain good performance.However,in general,we are more concerned with the magnetic field distribution in the active regions where various solar storms such as the solar flare and coronal mass ejection happen.In this paper,we fuse the self-attention mechanism with the pix2pix model which allows more computation resource and greater weight for strong magnetic regions.In addition,the attention features are concatenated by the Residual Hadamard Production(RHP) with the abstracted features after the encoder.We named our model as RHP-attention pix2pix.From the experiments,we can find that the proposed model can generate magnetograms with finer strong magnetic structures,such as sunspots.In addition,the polarity distribution of generated magnetograms at strong magnetic regions is more consistent with observed ones.
基金supported by the National Natural Science Foundation of China(NSFC,Grant Nos.11825301,12103066 and12073004).
文摘Magnetic fields play a key role in driving a broad range of dynamic phenomena in the atmospheres of the Sun and other stars.Routine and accurate measurements of the magnetic fields at all the atmospheric layers are of critical importance to understand these magnetic activities,but in the solar and stellar coronae such a measurement is still a challenge due to the weak field strength and the high temperature.Recently,a magnetic-field-induced transition(MIT)of Fe X at 257.26A has been proposed for the magnetic field measurements in the solar and stellar coronae.In this review,we present an overview of recent progresses in the application of this method in astrophysics.We start by introducing the theory underlying the MIT method and reviewing the existing atomic data critical for the spectral modeling of Fe X lines.We also discuss the laboratory measurements that verify the potential capability of the MIT technique as a probe for diagnosing the plasma magnetic fields.We then continue by investigating the suitability and accuracy of solar and stellar coronal magnetic field measurements based on the MIT method through forward modeling.Furthermore,we discuss the application of the MIT method to the existing spectroscopic observations obtained by the Extreme-ultraviolet Imaging Spectrometer onboard Hinode.This novel technique provides a possible way for routine measurements of the magnetic fields in the solar and stellar coronae,but still requires further efforts to improve its accuracy.Finally,the challenges and prospects for future research on this topic are discussed.
基金the Faculty of Science,University of Malaya(grant No.GPF081-2020)for their funding。
文摘We report detailed observation of the“herringbone”of a Type II solar radio burst that occurred on 2010 November 3rd.Data from the Space Weather Prediction Center,National Oceanic and Atmospheric Administration,e-CALLISTO,and Nan?ay Radio Heliograph are analyzed.We determine the brightness temperature and degree of circular polarization of the“herringbone”burst.Correlations between the physical parameters and the“herringbone”are examined.Based on the relationship,this is the first study that suggested this“herringbone”was generated through fundamental plasma.
基金supported by the National Natural Science Foundation of China(NSFC,grant No.11973056)the National Key R&D Program of China(grant No.2021YFA1600500)。
文摘Accurate measurement of magnetic fields is very important for understanding the formation and evolution of solar magnetic fields.Currently,there are two types of solar magnetic field measurement instruments:filter-based magnetographs and Stokes polarimeters.The former gives high temporal resolution magnetograms and the latter provides more accurate measurements of magnetic fields.Calibrating the magnetograms obtained by filter-based magnetographs with those obtained by Stokes polarimeters is a good way to combine the advantages of the two types.Our previous studies have shown that,compared to the magnetograms obtained by the Spectro-Polarimeter(SP)on board Hinode,those magnetograms obtained by both the filter-based Solar Magnetic Field Telescope(SMFT)of the Huairou Solar Observing Station and by the filter-based Michelson Doppler Imager(MDI)aboard SOHO have underestimated the flux densities in their magnetograms and systematic center-to-limb variations present in the magnetograms of both instruments.Here,using a sample of 75 vector magnetograms of stable alpha sunspots,we compare the vector magnetograms obtained by the Helioseismic and Magnetic Imager(HMI)aboard Solar Dynamics Observatory(SDO)with co-temporal vector magnetograms acquired by SP/Hinode.Our analysis shows that both the longitudinal and transverse flux densities in the HMI/SDO magnetograms are very close to those in the SP/Hinode magnetograms and the systematic center-to-limb variations in the HMI/SDO magnetograms are very minor.Our study suggests that using a filter-based magnetograph to construct a low spectral resolution Stokes profile,as done by HMI/SDO,can largely remove the disadvantages of the filter-type measurements and yet still possess the advantage of high temporal resolution.
基金supported by the National Natural Science Foundation of China(Grant Nos.10873038 and 10833007)the National Basic Research Program of China(973Program,2011CB811402).
文摘We statistically study the properties of emerging flux regions(EFRs)and response of the upper solar atmosphere to the flux emergence using data from the Helioseismic and Magnetic Imager and the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory.Parameters including total emerged flux,flux growth rate,maximum area,duration of the emergence and separation speed of the opposite polarities are adopted to delineate the properties of EFRs.The response of the upper atmosphere is addressed by the response of the atmosphere at different wavelengths(and thus at different temperatures).According to our results,the total emerged fluxes are in the range of(0.44-11.2)×1019 Mx while the maximum area ranges from 17 to 182 arcsec2.The durations of the emergence are between 1 and 12 h,which are positively correlated to both the total emerged flux and the maximum area.The maximum distances between the opposite polarities are 7-25 arcsec and are also positively correlated to the duration.The separation speeds are from 0.05 to 1.08 km s-1,negatively correlated to the duration.The derived flux growth rates are(0.1-1.3)×1019 Mx h-1,which are positively correlated to the total emerging flux.The upper atmosphere first responds to the flux emergence in the 1600Achromospheric line,and then tens to hundreds of seconds later,in coronal lines,such as the 171(T=105.8 K)and 211(T=106.3 K)lines almost simultaneously,suggesting the successive heating of the atmosphere from the chromosphere to the corona.
基金the Major Project 19791090, funded by theNational Natural Science FOundation of China (NSFC)
文摘There are only a few observations published so far that show the initiation of a coronal mass ejection (CME) and illustrate the magnetic changes in the surface origin of a CME. Any attempt to connect a CME with its local solar activities is meaningful. In this paper we present a clear instance of a halo CME initiation. A careful analysis of magnetograms shows that the only obvious magnetic changes in the surface region of the CME is a magnetic flux cancellation underneath a quiescent filament. The early disturbance was seen as the slow upward motion in segments of the quiescent filament. Four hours later, the filament was accelerated to about 50 km s-1 and erupted. While a small part of the material in the filament was ejected into the upper corona, most of the mass was transported to a nearby region. About forty minutes later, the transported mass was also ejected partially to the upper corona. The eruption of the filament triggered a two-ribbon flare, with post-flare loops connecting the flare ribbons. A halo CME, which is inferred to be associated with the eruptive filament, was observed from LASCO/C2 and C3. The halo CME contained two CME events, each event corresponded to a partial mass ejection of the filament. We suggest that the magnetic reconnection at the lower atmosphere is responsible for the filament eruption and the halo CME.
