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Observations of nonthermal and thermal hard X-ray spikes in an M-class flare
Ji, HS; Wang, HM; Schmahl, EJ; Qiu, J; Zhang, YA
AbstractWe report a study of an M2.3 flare, which occurred on 2002 September 9 in NOAA Active Region 0105. The observation was made at Big Bear Solar Observatory (BBSO) at the wavelength of Halpha - 1.3 Angstrom, with a cadence of 40 ms. The flare was also observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). Three kernels appear in Halpha - 1.3 Angstrom images, two of which are conjugate kernels. The light curves of the two conjugate kernels show a correlation with that of hard X-rays (HXRs) in the 25-50 keV band; however, the third one does not. We use HXR images and spectra and the time delay between the Halpha blue-wing emissions and HXRs to distinguish between the thermal and nonthermal character of spikes in the light curve. Among the four spikes we studied, the second spike is thermal, while the other three are nonthermal. What characterizes the thermal spike is the long time delay (similar to 10 s), the lack of HXR footpoint'' emission, and the absence of a powerlaw component in HXR imaging spectra. In addition, the spectrum of this spike is only well fitted by a double-temperature model with a hot (similar to 25.5 MK) component and a superhot (similar to47.1 MK) component with different emission measures. The nonthermal spikes are characterized by short time delays (less than or similar to4 s, the RHESSI time resolution used in this paper), HXR footpoint emission, and power-law spectra. The relative Halpha blue-wing intensities during the periods of the three nonthermal spikes are evaluated in terms of beam parameters: powerlaw index and X-ray flux at 10 keV. Comparison with the observations shows that the first spike of the early impulsive phase did not produce the predicted Halpha intensity.
KeywordSun : Activity Sun : Chromosphere Sun : Flares Sun : X-Rays, Gamma Rays
Subject AreaAstronomy & Astrophysics
WOS HeadingsScience & Technology ; Physical Sciences
Indexed BySCI
WOS Research AreaAstronomy & Astrophysics
WOS SubjectAstronomy & Astrophysics
WOS IDWOS:000220801900039
Citation statistics
Cited Times:16[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Affiliation1.New Jersey Inst Technol, Big Bear Solar Observ, Big Bear City, CA 92314 USA
2.Acad Sinica, Purple Mt Observ, Nanjing 210008, Peoples R China
3.Univ Maryland, Dept Astron, College Pk, MD 20742 USA
4.New Jersey Inst Technol, Ctr Solar Res, Newark, NJ 07102 USA
Recommended Citation
GB/T 7714
Ji, HS,Wang, HM,Schmahl, EJ,et al. Observations of nonthermal and thermal hard X-ray spikes in an M-class flare[J]. ASTROPHYSICAL JOURNAL,2004,605(2):938-947.
APA Ji, HS,Wang, HM,Schmahl, EJ,Qiu, J,&Zhang, YA.(2004).Observations of nonthermal and thermal hard X-ray spikes in an M-class flare.ASTROPHYSICAL JOURNAL,605(2),938-947.
MLA Ji, HS,et al."Observations of nonthermal and thermal hard X-ray spikes in an M-class flare".ASTROPHYSICAL JOURNAL 605.2(2004):938-947.
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