共查询到20条相似文献，搜索用时 22 毫秒
1.
Magnetic reconnection is commonly accepted to play a key role in flare energy release, but only poor information about the
main characteristics of this process is available so far. An intrinsic feature of reconnection is plasma density enhancement
in current sheets. A unique method to detect this effect is provided by analysis of drifting bursts, whose emission frequency
is close to the local Langmuir frequency or its harmonics. With this purpose, we analyze a series of several tens of drifting
microwave bursts during the 30 March 2001 flare. The burst drift rates range from −10 to 20 GHz s−1. Using one-dimensional scans recorded with the SSRT interferometer at two different frequencies near 5.7 GHz, we have measured
relative positions of burst sources and their velocities along a flare loop revealed from soft X-ray and extreme-ultraviolet
images. It is argued that the contribution of the increasing density effect into the observed frequency drift rates is about
6 GHz s−1, which is shown to be consistent with theoretical models of magnetic reconnection with reasonable boundary conditions. 相似文献
2.
G. N. Zubkova N. N. Kardapolova B. I. Lubyshev V. P. Nefedyev G. Ya. Smolkov R. A. Sych T. A. Treskov 《Astronomische Nachrichten》1990,311(5):313-315
This paper gives the main characteristics of the Siberian Solar Radio Telescope as well as some results derived by investigating the s-component sources and radio bursts on the Sun using the SSRT. 相似文献
3.
The relationship between the proton intensity in the interplanetary space and radio bursts of type II for 78 proton events
for the period of 1989–2005 is studied based on the data of the Radio Solar Telescope Network. Two families of events have
been revealed in plots describing the dependence of the intensity of protons with different energies and the rate of the frequency
drift of meter-decameter radio bursts. This suggests the generation of shock waves both in the region of flare energy release
and at the fronts of coronal mass ejection. 相似文献
4.
《天文和天体物理学研究(英文版)》2021,(6)
Solar radio spikes are one of the most intriguing spectral types of radio bursts. Their very short lifetimes, small source size and super-high brightness temperature indicate that they should be involved in some strong energy release, particle acceleration and coherent emission processes closely related to solar flares. In particular, for the microwave spike bursts, their source regions are much close to the related flaring source region which may provide the fundamental information of the flaring process. In this work,we identify more than 600 millisecond microwave spikes which recorded by the Solar Broadband Radio Spectrometer in Huairou(SBRS/Huairou) during an X3.4 solar flare on 2006 December 13 and present a statistical analysis about their parametric evolution characteristic. We find that the spikes have nearly the same probability of positive and negative frequency drifting rates not only in the flare rising phase, but also in the peak and decay phases. So we suppose that the microwave spike bursts should be generated by shockaccelerated energetic electrons, just like the terminational shock(TS) wave produced by the reconnection outflows near the loop top. The spike bursts occurred around the peak phase have the highest central frequency and obviously weak emission intensity, which imply that their source region should have the lowest position with higher plasma density due to the weakened magnetic reconnection and the relaxation of TS during the peak phase. The right-handed polarization of the most spike bursts may be due to the TS lying on the top region of some very asymmetrical flare loops. 相似文献
5.
A. M. Uralov V. V. Grechnev S. V. Lesovoi R. A. Sych N. N. Kardapolova G. Ya. Smolkov T. A. Treskov 《Solar physics》1998,178(1):119-124
Two-dimensional images obtained at the Siberian Solar Radio Telescope (SSRT) in the correlation mode are presented. The subject under discussion is the active region NOAA 7978 that produced a flare of X2.6 importance on 9 July 1996. Before the flare a compact, weakly polarized, and reasonably bright long-lived radio source was observed which we have identified as the Neutral Line associated Source (NLS). The correlation of radio and magnetographic images of the active region reveals the NLS brightness center to be localized over the inversion line of the photospheric magnetic field at the place of closest contact of opposite-polarity magnetic hills. 相似文献
6.
An uncommon fine structure in the radio spectrum consisting of bursts in absorption was observed with the Chinese Solar Broadband Radiospectrometer (SBRS) in the frequency range of 2.6?–?3.8 GHz during an X3.4/4B flare on 13 December 2006 in active region NOAA 10930 (S05W33). Usual fine structures in emission such as spikes, zebra stripes, and drifting fibers were observed at the peak of every new flare brightening. Within an hour at the decay phase of the event we observed bursts consisting of spikes in absorption, which pulsated periodically in frequency. Their instantaneous frequency bandwidths were found to be in the 75 MHz range. Moreover, in the strongest Type III-like bursts in absorption, the spikes showed stripes of the zebra-pattern (ZP) that drifted to higher frequencies. All spikes had the duration as short as down to the limit of the instrument resolution of ≈8 ms. The TRACE 195 Å images indicate that the magnetic reconnection at this moment occurred in the western edge of the flare loop arcade. Taking into account the presence of the reverse-drifting bursts in emission, in the course of the restoration of the magnetic structures in the corona, the acceleration of the beams of fast particles must have occurred both upward and downward at different heights. The upward beams will be captured by the magnetic trap, where the loss-cone distribution of fast particles (responsible for the emission of continuum and ZP) were formed. An additional injection of fast particles will fill the loss-cone later, breaking the loss-cone distribution. Therefore, the generation of continuum will be quenched at these moments, which was evidenced by the formation of bursts in absorption. 相似文献
7.
The multi-wavelength analysis is performed on a flare on September 9, 2002 with data of Owens Valley Solar Arrays (OVSA),
Big Bear Solar Observatory (BBSO), Ramaty High Energy Solar Spectroscopic Imager (RHESSI), and Extreme UV Imager Telescope
(EIT), and The Michelson Doppler Imager (MDI) on board of the Solar and Heliospheric Observatory (SOHO). The radio sources
at 4.8 and 6.2 GHz located in the intersection of two flaring loops at 195 of SOHO/EIT respectively with two dipole magnetic
fields of SOHO/MDI, in which one EIT loop was coincident with an X-ray loop of RHESSI at 12–25 keV, and two Hαbright kernels a1 and a2 of BBSO, respectively at the two footpoints of this loop; the second EIT loop connected another two
Hαkernels b1 and b2 and radio sources at 7.8 and 8.2 GHz of OVSA. The maximum phase of microwave bursts was evidently later
than that of hard X-ray bursts and Hαkernels a1 and a2, but consistent with that of Hαkernels b1 and b2. Moreover, the flare may be triggered by the interaction of the two flaring loops, which is suggested by
the cross-correlation of radio, optical, and X-ray light curves of a common quasi-periodic oscillation in the rising phase,
as well as two peaks at about 7 and 9 GHz of the microwave spectra at the peak times of the oscillation, while the bi-directional
time delays at two reversal frequencies respectively at 7.8 and 9.4 GHz (similar to the peak frequencies of the microwave
spectra) may indicate two reconnection sites at different coronal levels. The microwave and hard X-ray footpoint sources located
in different EUV and optical loops may be explained by different magnetic field strength and the pitch angle distribution
of nonthermal electrons in these two loops. 相似文献
8.
The Siberian Solar Radio Telescope: the current state of the instrument,observations, and data 总被引：2，自引：0，他引：2
Grechnev V.V. Lesovoi S.V. Smolkov G. Ya. Krissinel B.B. Zandanov V.G. Altyntsev A.T. Kardapolova N.N. Sergeev R.Y. Uralov A.M. Maksimov V.P. Lubyshev B.I. 《Solar physics》2003,216(1-2):239-272
The Siberian Solar Radio Telescope (SSRT) is one of the world's largest solar radio heliographs. It commenced operation in
1983, and since then has undergone several upgrades. The operating frequency of the SSRT is 5.7 GHz. Since 1992 the instrument
has had the capability to make one-dimensional scans with a high time resolution of 56 ms and an angular resolution of 15 arc sec.
Making one of these scans now takes 14 ms. In 1996 the capability was added to make full, two-dimensional images of the solar
disk. The SSRT is now capable of obtaining images with an angular resolution of 21 arc sec every 2 min. In this paper we describe
the main features and operation of the instrument, particularly emphasizing issues pertaining to the imaging process and factors
limiting data quality. Some of the data processing and analysis techniques are discussed. We present examples of full-disk
solar images of the quiet Sun, recorded near solar activity minimum, and images of specific structures: plages, coronal bright
points, filaments and prominences, and coronal holes. We also present some observations of dynamic phenomena, such as eruptive
prominences and solar flares, which illustrate the high-time-resolution observations that can be done with this instrument.
We compare SSRT observations at 5.7 GHz, including computed `light curves', both morphologically and quantatively, with observations
made in other spectral domains, such as 17 GHz radio images, Hα filtergrams and magnetograms, extreme-ultraviolet and X-ray
observations, and dynamic radio spectra. 相似文献
9.
A type IV radio burst accompanied by several normal- and reverse-drifting type III bursts, multiple long-term quasi-periodic pulsations and spikes was observed with the radio spectrometers (1.0–2.0 and 2.6–3.8 GHz) at National Astronomical Observatories of China (NAOC) on 23 September 1998. In combination with the images of Siberian Solar Radio Telescope (SSRT) of Russia, the complex and multiple magnetic structures inferred from the radio bursts reveal the existence of both large-scale and small-scale magnetic structures. This event suggests that the geometries of coronal magnetic fields contain multiple discrete electron acceleration/injection sites at different heights, and extended open and closed magnetic field lines. It can be shown that the energetic electrons gain access to open, diverging and closed field lines thus producing different types of radio bursts. From the characteristics of position, polarization, dispersion and displacement of the sources, the model of the type IV event is supported, which involves synchrotron emission from the electrons confined by the rapid scattering through the interaction of hydromagnetic wave with particles. 相似文献
10.
A statistical analysis of decimetric radio bursts (RBs), X-ray flares and coronal mass ejections (CMEs) is carried out. We
consider all radio bursts recorded by the Cracow Solar Radio Telescope from the beginning of 1996 until the end of 2004. It
is found that the decimetric radio bursts are associated and strongly correlated with X-ray flares. Correlation coefficients
between RBs durations and the maximal fluxes of the radio bursts and flares are found to be 0.60 and 0.87, respectively. We
also demonstrated that a significant population of the decimetric radio bursts are associated with CMEs. The correlation coefficient
between the maximal radio flux density multiplied by the duration of the RBs versus velocity multiplied by width of CMEs is
found to be 0.55. 相似文献
11.
We have selected 27 solar microwave burst events recorded by the Solar Broadband Radio Spectrometer (SBRS) of China, which were accompanied by M/X class flares and fast CMEs. A total of 70.4% of radio burst events peak at 2.84 GHz before the peaks of the related flares’ soft X-ray flux with an average time difference of about 6.7 minutes. Almost all of the CMEs start before or around the radio burst peaks. At 2.6?–?3.8 GHz bandwidth, 234 radio fine structures (FSs) were classified. More often, some FSs appear in groups, which can contain several individual bursts. It is found that many more radio FSs occur before the soft X-ray maxima and even before the peaks of radio bursts at 2.84 GHz. The events with high peak flux at 2.84 GHz have many more radio FSs and the durations of the radio bursts are independent of the number of radio FSs. Parameters are given for zebra patterns, type III bursts, and fiber structures, and the other types of FSs are described briefly. These radio FSs include some special types of FSs such as double type U bursts and W-type bursts. 相似文献
12.
Ground level enhancements (GLEs) of cosmic-ray intensity occur, on average, once a year. Because they are rare, studying the solar sources of GLEs is especially important to approach understanding their origin. The SOL2001-12-26 eruptive-flare event responsible for GLE63 seems to be challenging in some aspects. Deficient observations limited our understanding of it. Analysis of additional observations found for this event provided new results that shed light on the flare configuration and evolution. This article addresses the observations of this flare with the Siberian Solar Radio Telescope (SSRT). Taking advantage of its instrumental characteristics, we analyze the detailed SSRT observations of a major long-duration flare at 5.7 GHz without cleaning the images. The analysis confirms that the source of GLE63 was associated with an event in active region 9742 that comprised two flares. The first flare (04:30?–?05:03 UT) reached a GOES importance of about M1.6. Two microwave sources were observed, whose brightness temperatures at 5.7 GHz exceeded 10 MK. The main flare, up to an importance of M7.1, started at 05:04 UT and occurred in strong magnetic fields. The observed microwave sources reached a brightness temperature of about 250 MK. They were not static. After appearing on the weaker-field periphery of the active region, the microwave sources moved toward each other nearly along the magnetic neutral line, approaching the stronger-field core of the active region, and then moved away from the neutral line like expanding ribbons. These motions rule out an association of the non-thermal microwave sources with a single flaring loop. 相似文献
13.
The so-called zebra structures in radio dynamic spectra, specifically their frequencies and frequency drifts of emission stripes,
contain information on the plasma parameters in the coronal part of flare loops. This paper presents observations of zebra
structures in a microwave range. Dynamic spectra were recorded by Chinese spectro-polarimeters in the frequency band close
to the working frequencies of the Siberian Solar Radio Telescope. The emission sources are localized in the flare regions,
and we are able to estimate the plasma parameters in the generation sites using X-ray data. The interpretation of the zebra
structures in terms of existing theories is discussed. The conclusion has been arrived at that the preferred generation mechanism
of zebra structures in the microwave range is the conversion of plasma waves to electromagnetic emission on the double plasma
resonance surfaces distributed across a flare loop. 相似文献
14.
Type II radio bursts are produced by material moving outwards in the solar atmosphere. Their drift in frequency allows the calculation of the radial speed with which the shock is moving- very basic information in assessing the likelihood that the shock will reach the Earth and its time of arrival. This paper compares the shock speeds derived from radio bursts observed by the Swept Frequency Interferometric Radiometer (SFIR) equipment at the US Air Force Radio Solar Telescope Network (RSTN) of observatories with those measured with the Culgoora radiospectrograph operated by IPS Radio and Space Services. The SFIR shock speeds are found to be 1.5–3.0 times larger than the Culgoora values which are consistent with earlier results. This difference appears to originate from the incorrect interpretation of events as a result of the smaller frequency range of the SFIR equipment. 相似文献
15.
Using a new type of oscillation map, made from the radio spectra by the wavelet technique, we study the 18 April 2014 M7.3 flare (SOL2014-04-18T13:03:00L245C017). We find a quasi-periodic character of this flare with periods in the range 65?–?115 seconds. At the very beginning of this flare, in connection with the drifting pulsation structure (plasmoid ejection), we find that the 65?–?115 s oscillation phase slowly drifts towards lower frequencies, which indicates an upward propagating wave initiated at the start of the magnetic reconnection. Many periods (1?–?200 seconds) are found in the drifting pulsation structure, which documents multi-scale and multi-periodic processes. On this drifting structure, fiber bursts with a characteristic period of about one second are superimposed, whose frequency drift is similar to that of the drifting 65?–?115 s oscillation phase. We also checked periods found in this flare by the EUV Imaging Spectrometer (EIS)/Hinode and Interface Region Imaging Spectrograph (IRIS) observations. We recognize the type III bursts (electron beams) as proposed, but their time coincidence with the EIS and IRIS peaks is not very good. The reason probably is that the radio spectrum is a whole-disk record consisting of all bursts from any location, while the EIS and IRIS peaks are emitted only from locations of slits in the EIS and IRIS observations. 相似文献
16.
The correlation between the proton flux intensity I p with the energies E p > 1?100 MeV and radio burst parameters for 107 solar energetic events is considered using the observation data for 1989?C2005 obtained with GOES and Wind satellites, as well as the Radio Solar Telescope Network (RSTN). It has been revealed that 73 and 77% of the events were accompanied by type-II radio bursts in the meter (m II, 25?C299 MHz) and the decameter-hectometer (DH II, 20 kHz?C14 MHz) wavelength ranges, respectively. The correlation coefficient between I p and the frequency drift velocity of the type-II bursts V II did not exceed 0.40. As V II increased, the intensity of I p increased for the m-II bursts and decreased for the DH-II bursts. Coronal shock waves accelerate protons more efficiently than interplanetary waves, and their contribution to acceleration increases with an increase in the particle energy E p . The acceleration of solar energetic particles in the region of the flare energy release is predominant. 相似文献
17.
Solar radiophysics is a rapidly developing branch of solar physics and plasma astrophysics. Solar radiophysics has the goal of analyzing observations of radio emissions from the Sun and understanding basic physical processes operating in quiet and active regions of the solar corona. In the near future, the commissioning of a new generation of solar radio observational facilities, which include the Chinese Spectral Radio Heliograph（CSRH） and the upgrade of the Siberian Solar Radio Telescope（SSRT）, and the beginning of solar observations with the Atacama Large Millimeter/submillimeter Array（ALMA）, is expected to bring us new breakthrough results of a transformative nature. The Marie-Curie International Research Staff Exchange（MC IRSES） “RadioSun” international network aims to create a solid foundation for the successful exploitation of upcoming solar radio observational facilities, as well as intensive use of the existing observational tools, advanced theoretical modeling of relevant physical processes and observables, and training a new generation of solar radio physicists. The RadioSun network links research teams from China,Czech Republic, Poland, Russia and the UK. This mini-volume presents research papers based on invited reviews and contributed talks at the 1st RadioSun workshop in China. These papers cover a broad range of research topics and include recent observational and theoretical advances in solar radiophysics, MHD seismology of the solar corona, physics of solar flares, generation of radio emission, numerical modeling of MHD and plasma physics processes, charged-particle acceleration and novel instrumentation. 相似文献
18.
We analyze the high-frequency drift radio structures observed by the spectrometer at Purple Mountain Observatory (PMO) over
the frequency range of 4.5 – 7.5 GHz during the 18 March 2003 solar flare. The drifting structures take place before the soft
X-ray maximum, almost at the maximum of hard X-ray flux at 25 – 50 keV. For the first time, the positive drift in this kind
of radio structures is detected in such a high frequency range. Their global drifting rate is roughly estimated as 3.6 GHz s−1. They appear in four groups, lasting in total for less than 6 s, and have a broad bandwidth of more than 2 GHz but a smaller
ratio of the bandwidth of the drifting structures to mean frequency than that of the lower frequency range. The lifetime of
each individual burst in this event can be derived by using the high temporal resolution of the spectrometer at PMO and has
an average value of 36.3 ms. Since the negative drifting structures observed in the 0.6 – 4.5 GHz frequency range were interpreted
to be a radio signature of a plasmoid ejected upward (moving out of the Sun), the present observation may imply that it is
possible for a plasmoid to move downward during a solar flare. However, for a confirmation of this suggestion direct radio
imaging observation would be needed. 相似文献
19.
L. O. T. Fernandes P. Kaufmann E. Correia C. G. Giménez de Castro A. S. Kudaka A. Marun P. Pereyra J.-P. Raulin A. B. M. Valio 《Solar physics》2017,292(1):21
Previous sub-THz studies were derived from single-event observations. We here analyze for the first time spectral trends for a larger collection of sub-THz bursts. The collection consists of a set of 16 moderate to small impulsive solar radio bursts observed at 0.2 and 0.4 THz by the Solar Submillimeter-wave Telescope (SST) in 2012?–?2014 at El Leoncito, in the Argentinean Andes. The peak burst spectra included data from new solar patrol radio telescopes (45 and 90 GHz), and were completed with microwave data obtained by the Radio Solar Telescope Network, when available. We critically evaluate errors and uncertainties in sub-THz flux estimates caused by calibration techniques and the corrections for atmospheric transmission, and introduce a new method to obtain a uniform flux scale criterion for all events. The sub-THz bursts were searched during reported GOES soft X-ray events of class C or larger, for periods common to SST observations. Seven out of 16 events exhibit spectral maxima in the range 5?–?40 GHz with fluxes decaying at sub-THz frequencies (three of them associated to GOES class X, and four to class M). Nine out of 16 events exhibited the sub-THz spectral component. In five of these events, the sub-THz emission fluxes increased with a separate frequency from that of the microwave spectral component (two classified as X and three as M), and four events have only been detected at sub-THz frequencies (three classified as M and one as C). The results suggest that the THz component might be present throughout, with the minimum turnover frequency increasing as a function of the energy of the emitting electrons. The peculiar nature of many sub-THz burst events requires further investigations of bursts that are examined from SST observations alone to better understand these phenomena. 相似文献
20.
Min Wang Rui-Xiang Xie Chun Xu Shuo-Biao Shi Yi-Hua Yan National Astronomical Observatories Yunnan Observatory Chinese Academy of Sciences Kunming National Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2005,5(5):508-518
We present a, large complex radio burst and its associated fast tune structures observed on 2001 April 10 in the frequency range of 0.65-7.6 GHz. The NoRH radio image observation shows very complex radio source structures which include preexisting, newly emerging, submerging/cancelling polarities and a bipolar, a tripolar (a 'bipolar + remote unipolar'), and a quadrupolar structure. This suggests that the radio burst is generated from a very complicated loop structure. According to the spectral and image observations, we assume that the beginning of this flare was caused by a single bipolar loop configuration with a 'Y-type' re-connection structure. A composite of radio continuum and fast time structures is contained in this flare. The various fast radio emission phenomena include normal and reverse drifting type III bursts, and slowly drifting and no-drift structures. The tripolar configurations may form a double-loop with a 'three-legged' structure, which is an important source of the various types of fast time structures. The two-loop reconnection model can lead simultaneously to electron acceleration and corona heating. We have also analyzed the behaviors of coronal magnetic polarities and the emission processes of different types radio emission qualitatively. Interactions of a bipolar or multi-polar loop are consistent with our observational results. Our observations favor the magnetic reconnection configurations of the 'inverted Y-type' (bipolar) and the 'three-legged' structures (tripolar or quadrupolar). 相似文献