Spatio-temporal Evolution of Sources of Microwave and Hard X-ray Pulsations of the Solar Flare using the NoRH,RHESSI, and AIA/SDO Observation Data

This paper reports the obtained analysis data on the spatio-temporal evolution of sources of microwave and hard X-ray pulsations for the SOL2011-06-07T06:16 event based on the observation data of the RHESSI spectrometer and the Nobeyama radioheliograph. The position of the considered pulsation sources changes from one pulsation to another. The motion of the X-ray sources is predominantly longitudinal in nature in relation to the inversion line of the magnetic polarity. The obtained analysis data on the evolution of X-ray sources are in good agreement with the results of the radio image analysis. The radio brightness center at 34 GHz changes its position from one pulsation to another along the inversion line of the magnetic polarity throughout the burst. According to the AIA/SDO telescope data, the flare region images in the ultraviolet range demonstrate a well-defined eruption of the magnetic flux rope. The flare energy release can likely be triggered by the erupting magnetic flux rope; the successive interaction of different parts of it with different loops of the surrounding magnetic arcade can result in their successive “ignition” and, as a consequence, lead to the observed changes in the position of X-ray and microwave sources from one pulsation to another.     

Compton Scattering of the Hard X-Ray Flux of Solar Flares with Various Angular Anisotropies of Hard X-Ray Sources

Geomagnetism and Aeronomy - The contribution of photons reflected from the solar photosphere to the intensity and the change in the slope of the energy spectrum of solar flare hard X-rays were...     

Quasi-Periodic Hard X-Ray Pulsations in Solar Flares Based on RHESSI and Konus-Wind Data

Geomagnetism and Aeronomy - The results of the study of quasi-periodic hard X-ray pulsations in solar flares with respect to the spatial localization of emission sources based on data from the...     

Estimate of Variations in the Parameters of the Midlatitude Lower Ionosphere Caused by the Solar Flare of September 10, 2017

Geomagnetism and Aeronomy - Changes in the state of the D and E ionospheric regions lead to variations in the amplitude-phase characteristics of VLF radio signals. The existing theoretical and...     

Features of Microwave Radiation and Magnetographic Characteristics of Solar Active Region NOAA 12242 Before the X1.8 Flare on December 20, 2014

This paper continues the cycle of authors’ works on the detection of precursors of large flares (M5 and higher classes) in active regions (ARs) of the Sun by their microwave radiation and magnetographic characteristics. Generalization of the detected precursors of strong flares can be used to develop methods for their prediction. This paper presents an analysis of the development of NOAA AR 12242, in which an X1.8 flare occurred on December 20, 2014. The analysis is based on regular multiazimuth and multiwavelength observations with the RATAN-600 radio telescope in the range 1.65–10 cm with intensity and circular polarization analysis and data from the Solar Dynamics Observatory (SDO). It was found that a new component appeared in the AR microwave radiation two days before the X-flare. It became dominant in the AR the day before the flare and significantly decreased after the flare. The use of multiazimuth observations from RATAN-600 and observations at 1.76 cm from the Nobeyama Radioheliograph made it possible to identify the radio source that appeared before the X-flare with the site of the closest convergence of opposite polarity fields near the neutral line in the AR. It was established that the X-flare occurred 20 h after the total gradient of the magnetic field of the entire region calculated from SDO/HMI data reached its maximum value. Analysis of the evolution of the microwave source that appeared before the X-flare in AR 12242 and comparison of its parameters with the parameters of other components of the AR microwave radiation showed that the new source can be classified as neutral line associated sources (NLSs), which were repeatedly detected by the RATAN-600 and other radio telescopes 1–3 days before the large flares.     

Microwave Emission of a Flare Loop in the Presence of Whistler Turbulence

Geomagnetism and Aeronomy - The mutual influence of whistler turbulence and fast nonthermal electrons injected into a coronal flare loop is considered. For the loop, аs the inhomogeneous and...     

On the Source of Sub-Terahertz Radiation of the Solar Flare on April 2, 2017

Geomagnetism and Aeronomy - The study analyzes the millimeter emission of a solar flare on April 2, 2017, observed by the Bauman Moscow State Technical University telescope RT-7.5. Based on the...     

Simulation of Subterahertz Emission from the April 2, 2017 Solar Flare Based on the Multiwavelength Observations

Geomagnetism and Aeronomy - Millimeter (93 and 140 GHz) emission of the М6.4 solar flare detected on April 2, 2017 in the NOAA 12644 active region by the RT-7.5 telescope of the Bauman Moscow...     

亚洲地震委员会第四次学术大会于2002年11月在尼泊尔加德满都举行

亚洲地震委员会（ASC）第四次学术大会暨地震学、地震危险性评估和地震风险管理学术讨论会于2002年11月24－26日在尼泊尔加德满都举行。来自亚洲、大洋洲、美洲和欧洲的22个国家的近200名专家出席了会议，会议共收到约110篇研究报告。文章介绍了大会、学术交流和ASC工作会议等情况。     

Flare coronal loop heating and hard X-ray emission from solar flares of August 23, 2005, and November 9, 2013

The thermal balance and hard X-ray emission of coronal loops for two solar events have been considered in the scope of a “standard” flare model. An important role of the thermal energy release is justified by the event of August 23, 2005, as an example. For the flare of November 9, 2013, it has been established that electrons accelerated at a flare loop top cannot maintain the observed hard X-ray fluxes from the flare footpoints, which indicates that charged particles are additionally accelerated in the chromosphere.

     

Cyclotron Line in Solar Microwave Radiation by Radio Telescope RATAN-600 Observations of the Solar Active Region NOAA 12182

This paper presents the results of observation of a rare phenomenon—a narrowband increase in the brightness of cyclotron radiation of one of the structural details of a radio source located in the solar corona above the solar active region NOAA 12182 in October 2014 at a frequency of 4.2 ± 0.1 GHz. The brightness of radiation in the maximum of the phenomenon has reached 10 MK; its duration was equal to 3 s. The exact location of the source of the narrowband cyclotron radiation is indicated: it is a corona above a fragmented (4-nuclear) sunspot, on which a small UV flare loop was closed.

     

Event of the November 7–10, 2004, magnetic storm in the lower ionosphere

The results of magnetometric observations and radar studies of the lower ionosphere during the superstrong magnetic storm (geospace storm) of November 7–10, 2004, are presented and analyzed. An increase in the electron density and in the amplitudes of its aperiodic and quasi-periodic variations at high level of magnetic activity is detected. In individual time intervals, the relation of Pc5-6 magnetic pulsations to short-period (5–15 min) wave disturbances in the electron density in the lower ionosphere was observed.     

Signs of Preflare Situation in Solar Ultraviolet and Microwave Emission

Geomagnetism and Aeronomy - The spatial dynamics of microwave emission (data from the Nobeyama Radioheliograph) of active regions with a complex magnetic field configuration before powerful flares,...     

Book Review: Earthquake Processes: Physical Modeling,Numerical Simulation and Data Analysis,Part I and II by M. Matsu'ura,P. Mora,A. Donnellan and X. Yin (Eds.), Birkhäuser Verlag,Basel-Boston-Berlin, 2002, ISBN 3-7643-6915-9 and 6916-7

Studia Geophysica et Geodaetica -     

Influence of Whistler Turbulence on Fast Electron Distribution and Their Microwave Emissions in a Flare Loop

The influence of whistlers on the distribution and gyrosynchrotron radiation of fast electrons injected into a coronal magnetic trap is considered. The kinetic equation in the Fokker–Planck approximation with consideration of fast electron scattering, both on background plasma particles and on whistlers, is solved for an inhomogeneous trap. It is supposed that the source of whistlers is a nonstationary process of flare energy release. Having found the fast electron distribution, we can calculate their gyrosynchrotron microwave emission. The influence of nonthermal electron scattering on whistlers are compared with the effects of scattering on Coulomb collisions. It is shown that whistlers considerably modify the emission characteristics of a loop at a certain energy density; in particular, they steepen the frequency spectrum. This is useful for microwave diagnostics of plasma turbulence in the flare loop.     

2002年10～11月华北地区ML≥3.0地震动态

根据中国地震局分析预报中心提供的资料 ,2 0 0 2年 1 0月华北地区 ( 3 3 0°～ 42 0°Ｎ ,1 1 1 0°～ 1 2 5 0°Ｅ)共发生ＭＬ≥ 3 0地震 8次 (见表 1 ) ,其中 1 2日 0 0时 55分大同ＭＬ4 0地震是本月最显著的事件。本月地震频度略低于上月 ,参考 1 992年以来的月平均地震频次 ,1 0月处于中等偏低水平 ,地震活动月能量释放处于中等状态 ,震中主要分布在山西带和东部沿海及海域。1 1月共发生ＭＬ≥ 3 0地震 6次 (见表 1 ) ,其中 7日 1 4时 3 4分郑州ＭＬ4 5地震是本月最显著的事件。本月地震频度与上月相比又略有下降 ,仍处于中等偏低…     

Characteristics of Soft X-Ray Radiation of the Solar Active Region NOAA 1024 Registered by the PINGVIN-M Device in July 2009

Geomagnetism and Aeronomy - The paper presents the results of processing of data on the soft X-ray solar radiation obtained by the PINGVIN-M instrument aboard the KORONAS-FOTON spacecraft in July...