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Article: Millimeter, microwave, hard X-ray, and soft X-ray observations of energetic electron populations in solar flares

TitleMillimeter, microwave, hard X-ray, and soft X-ray observations of energetic electron populations in solar flares
Authors
KeywordsSun: Flares
Sun: Radio Radiation
Sun: X-Rays, Gamma Rays
Issue Date1994
Citation
Astrophysical Journal, Supplement Series, 1994, v. 90 n. 2, p. 599-610 How to Cite?
AbstractWe present comparisons of multiwavelength data for a number of solar flares observed during the major campaign of 1991 June. The different wavelengths are diagnostics of energetic electrons in different energy ranges: soft X-rays are produced by electrons with energies typically below 10 keV, hard X-rays by electrons with energies in the range 10-200 keV, microwaves by electrons in the range 100 keV-1 MeV, and millimeter-wavelength emission by electrons with energies of 0.5 MeV and above. The flares in the 1991 June active period were remarkable in two ways: all have very high turnover frequencies in their microwave spectra, and very soft hard X-ray spectra. The sensitivity of the microwave and millimeter data permit us to study the more energetic (>0.3 MeV) electrons even in small flares, where their high-energy bremsstrahlung is too weak for present detectors. The millimeter data show delays in the onset of emission with respect to the emissions associated with lower energy electrons and differences in time profiles, energy spectral indices incompatible with those implied by the hard X-ray data, and a range of variability of the peak flux in the impulsive phase when compared with the peak hard X-ray flux which is two orders of magnitude larger than the corresponding variability in the peak microwave flux. All these results suggest that the hard X-ray-emitting electrons and those at higher energies which produce millimeter emission must be regarded as separate populations. This has implications for the well-known "number problem" found previously when comparing the numbers of nonthermal electrons required to produce the hard X-ray and radio emissions.
Persistent Identifierhttp://hdl.handle.net/10722/174615
ISSN
2015 Impact Factor: 11.257
2015 SCImago Journal Rankings: 6.522

 

DC FieldValueLanguage
dc.contributor.authorKundu, MRen_US
dc.contributor.authorWhite, SMen_US
dc.contributor.authorGopalswamy, Nen_US
dc.contributor.authorLim, Jen_US
dc.date.accessioned2012-11-26T08:46:31Z-
dc.date.available2012-11-26T08:46:31Z-
dc.date.issued1994en_US
dc.identifier.citationAstrophysical Journal, Supplement Series, 1994, v. 90 n. 2, p. 599-610en_US
dc.identifier.issn0067-0049en_US
dc.identifier.urihttp://hdl.handle.net/10722/174615-
dc.description.abstractWe present comparisons of multiwavelength data for a number of solar flares observed during the major campaign of 1991 June. The different wavelengths are diagnostics of energetic electrons in different energy ranges: soft X-rays are produced by electrons with energies typically below 10 keV, hard X-rays by electrons with energies in the range 10-200 keV, microwaves by electrons in the range 100 keV-1 MeV, and millimeter-wavelength emission by electrons with energies of 0.5 MeV and above. The flares in the 1991 June active period were remarkable in two ways: all have very high turnover frequencies in their microwave spectra, and very soft hard X-ray spectra. The sensitivity of the microwave and millimeter data permit us to study the more energetic (>0.3 MeV) electrons even in small flares, where their high-energy bremsstrahlung is too weak for present detectors. The millimeter data show delays in the onset of emission with respect to the emissions associated with lower energy electrons and differences in time profiles, energy spectral indices incompatible with those implied by the hard X-ray data, and a range of variability of the peak flux in the impulsive phase when compared with the peak hard X-ray flux which is two orders of magnitude larger than the corresponding variability in the peak microwave flux. All these results suggest that the hard X-ray-emitting electrons and those at higher energies which produce millimeter emission must be regarded as separate populations. This has implications for the well-known "number problem" found previously when comparing the numbers of nonthermal electrons required to produce the hard X-ray and radio emissions.en_US
dc.languageengen_US
dc.relation.ispartofAstrophysical Journal, Supplement Seriesen_US
dc.subjectSun: Flaresen_US
dc.subjectSun: Radio Radiationen_US
dc.subjectSun: X-Rays, Gamma Raysen_US
dc.titleMillimeter, microwave, hard X-ray, and soft X-ray observations of energetic electron populations in solar flaresen_US
dc.typeArticleen_US
dc.identifier.emailLim, J: jjlim@hku.hken_US
dc.identifier.authorityLim, J=rp00745en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.scopuseid_2-s2.0-0000562019en_US
dc.identifier.volume90en_US
dc.identifier.issue2en_US
dc.identifier.spage599en_US
dc.identifier.epage610en_US
dc.publisher.placeUnited Statesen_US
dc.identifier.scopusauthoridKundu, MR=7102095820en_US
dc.identifier.scopusauthoridWhite, SM=7404079906en_US
dc.identifier.scopusauthoridGopalswamy, N=7005931847en_US
dc.identifier.scopusauthoridLim, J=7403453870en_US

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