Solar gradual hard x-ray bursts and associated phenomena
From an examination of the white light coronagraph, H/sub alpha/, and radio (microwave, decimetric, and metric) data associated with a sample of 10 gradual hard x-ray bursts (GHBs) observed with the Hard-X-Ray-Burst Spectrometer on SMM and the x-ray detector on ISEE 3, was found the following: (1) The hard (somewhat > 30 keV) X ray photon energy spectrum began to harden near the onset of the GHBs, became systematically harder through the peak of the events, and continued to harden (or at least did not become softer) during the decay phase. (2) A coronal mass ejection (CME) was observed, or inferred to have occurred, in association with at least nine of the 10 GHBs, and CMEs appeared to precede the GHBs, by times ranging from 5 to 60 minutes. (3) The GHBs characteristically occurred in the late phase of major flares; in general, the changes in H/sub alpha/ flare brightness and area during GHBs were small and not commensurate with their associated microwave-burst peak intensities. (4) The centimeter wavelength bursts associated with the GHBs had relatively low frequency spectral maxima, and were microwave rich in relation to the observed hard x-ray emission. (5) The associated decimetric bursts typically exhibited significant intensity variations on time scales of from about 0.1 to somewhat > 1 minute, short in comparison with the somewhat > 10 minute durations of the gradual x-ray/microwave bursts. (6) The GHBs were poorly associated with the coincident metric type-II bursts and more strongly associated with type-IV or continuum events.
- Research Organization:
- Air Force Geophysics Lab., Hanscom AFB, MA (USA)
- OSTI ID:
- 6903849
- Report Number(s):
- AD-A-173330/2/XAB; AFGL-TR-86-0215
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
SOLAR FLARES
SOLAR RADIO BURSTS
SOLAR X-RAY BURSTS
ENERGY SPECTRA
BALMER LINES
SOLAR CORONA
ATMOSPHERES
ELECTROMAGNETIC RADIATION
RADIATIONS
RADIOWAVE RADIATION
SOLAR ACTIVITY
SPECTRA
STELLAR ATMOSPHERES
STELLAR CORONAE
640104* - Astrophysics & Cosmology- Solar Phenomena