Microwave and Hard X-Ray Spectral Evolution for the 13 December 2006 Solar Flare

Ning, Zhouyu

doi:10.1007/s11207-007-9101-8

Cited by 17 publications

(14 citation statements)

References 40 publications

(16 reference statements)

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“…This flare exhibited HXR emission from two footpoints and a loop-top microwave source, and the authors argue that their model can explain the observation that the radio-emitting electrons appear to have a spectrum harder than that of the HXR-emitting electrons. As time proceeds, higher energy electrons will tend to concentrate in the trapped population of coronal loops, and this can explain observations such as the gradual hardening of the microwave spectrum even when the HXR spectrum is softening (e.g., Ning 2007Ning , 2008a.…”

Section: Transport Effectsmentioning

confidence: 99%

The Relationship Between Solar Radio and Hard X-ray Emission

et al. 2011

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This review discusses the complementary relationship between radio and hard X-ray observations of the Sun using primarily results from the era of the Reuven Ramaty High Energy Solar Spectroscopic Imager satellite. A primary focus of joint radio and hard X-ray studies of solar flares uses observations of nonthermal gyrosynchrotron emission at radio wavelengths and bremsstrahlung hard X-rays to study the properties of electrons accelerated in the main flare site, since it is well established that these two emissions show very similar temporal behavior. A quantitative prescription is given for comparing the electron energy distributions derived separately from the two wavelength ranges: this is an important application with the potential for measuring the magnetic field strength in the flaring region, and reveals significant differences between the electrons in different energy ranges. Examples of the use of simultaneous data from the two wavelength ranges to derive physical conditions are then discussed, including the case of microflares, and the comparison of images at radio and hard X-ray wavelengths is presented. There have been puzzling results obtained from observations of solar flares at millimeter and submillimeter wavelengths, and the comparison of these results with corresponding hard X-ray data is presented. Finally, the review discusses the association of hard X-ray releases with radio emission at decimeter and meter wavelengths, which is dominated by plasma emission (at lower frequencies) and electron cyclotron maser emission (at higher frequencies), both coherent emission mechanisms that require small numbers of energetic electrons. These comparisons show broad general associations but detailed correspondence remains more elusive.

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Section: Transport Effectsmentioning

confidence: 99%

The Relationship Between Solar Radio and Hard X-ray Emission

et al. 2011

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“…On the other hand, NoRP fully covered this flare in microwave emissions and simultaneously the GOES spacecraft has observed this event in soft X-ray emissions from the Sun before, during and after the flare. For this flare event, the flare intensity was highest at 02:25 UT as seen in microwave emission observations from NoRP (Ning 2008;Minoshima et al 2009). However, the soft X-ray observations from GOES show peak intensity around 02:35 UT.…”

Section: Analysis Of Velocity Signals In the Active Region Using Gong...mentioning

confidence: 52%

“…A further opportunity to examine this effect was seen in active region NOAA 10930 which appeared on the solar disk during December 2006 and produced a lot of space weather related activity (Li et al 2009;Ning 2008). The most intense flare (of class X3.4) in this active region was reported on 13 December 2006.…”

Section: Introductionmentioning

confidence: 99%

On the Flare-Induced Seismicity in the Active Region Noaa 10930 and Related Enhancement of Global Waves in the Sun

Kumar

Venkatakrishnan

Mathur

et al. 2011

ApJ

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A major flare (of class X3.4) occurred on 13 December 2006 in the active region NOAA 10930. This flare event has remained interesting for solar researchers for studies related to particle acceleration during the flare process and the reconfiguration of magnetic fields as well as fine scale features in the active region. The energy released during flares is also known to induce acoustic oscillations in the Sun. Here, we analyze the line-of-sight velocity patterns in this active region during the X3.4 flare using the Dopplergrams obtained by Global Oscillation Network Group (GONG) instrument. We have also analyzed the disk-integrated velocity observations of the Sun obtained by Global Oscillation at Low Frequency (GOLF) instrument onboard SOHO (Solar and Heliospheric Observatory) spacecraft as well as full-disk collapsed velocity signals from GONG observations during this flare to study any possible connection between the flare related changes seen in the local and global velocity oscillations in the Sun. We apply wavelet transform to the time series of the localized velocity oscillations as well as the global velocity oscillations in the Sun spanning the flare event.The line-of-sight velocity shows significant enhancement in some localized regions of the penumbra of this active region during the flare. The affected region is seen to be away from the locations of the flare ribbons and the hard X-ray footpoints. The sudden enhancement in this velocity seems to be caused by the Lorentz force driven by the "magnetic jerk" in the localized penumbral region.Application of wavelet analysis to these flare induced localized seismic signals show significant enhancement in the high-frequency domain (5<ν<8 mHz) and a feeble enhancement in the p-mode oscillations (2<ν<5 mHz) during the flare.On the other hand, the wavelet analysis of GOLF velocity data and the fulldisk collapsed GONG velocity data spanning the flare event indicate significant -4post-flare enhancements in the high-frequency global velocity oscillations in the Sun as evident from the Wavelet Power Spectrum and the corresponding scaleaverage variance. The present observations of the flare induced seismic signals in the active region in context to the driving force is different as compared to the previous reports on such cases. We also find indications of a connection between flare induced localized seismic signals and the excitation of global high-frequency oscillations in the Sun.

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“…We only use the front segments of the detectors, and excluded the detectors 2 and 7. The same method was used to study time evolution of hard X-ray spectral index in our recent papers (Ning 2007a(Ning , 2007b(Ning , 2008. In order to rule out the background effect, it is better to not extend the fits below typically 6 keV, where the RHESSI response is not as well determined.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

Magnetic reconnection rate and spectral index for two double-ribbon flares

Ning

2008

Astrophys Space Sci

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We explore the correlations between the inferred reconnection rate and hard X-ray spectral hardness for two double-ribbon flares on 2003 November 1 and 2005 May 17 in this paper. The magnetic reconnection rate of ϕ rec is derived from the time rate of change of the product between the normal magnetic field and the newly brightened ribbon area of TRACE 1600 Å observations. And the spectral index of γ is derived from RHESSI hard X-ray data. Both events show a soft-hard-soft spectral behaviour in the risepeak-decay phases. An anti-correlated behaviour is found between the time evolution of reconnection rate and spectral index. From the regression analysis, we obtain a negative power-law dependence and quantify the relationship between these two quantities. This is consistent with the simulation results before, and further confirms the importance of magnetic reconnection for the electron acceleration in solar flares.

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Microwave and Hard X-Ray Spectral Evolution for the 13 December 2006 Solar Flare

Cited by 17 publications

References 40 publications

The Relationship Between Solar Radio and Hard X-ray Emission

The Relationship Between Solar Radio and Hard X-ray Emission

On the Flare-Induced Seismicity in the Active Region Noaa 10930 and Related Enhancement of Global Waves in the Sun

Magnetic reconnection rate and spectral index for two double-ribbon flares

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