Correlated observations of impulsive UV and hard X-ray bursts in solar flares from the Solar Maximum Mission

Journal Article · Thu Mar 15 04:00:00 EST 1984 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/161854· OSTI ID:6747195

Cheng, C; Tandberg-Hanssen, Einar; Orwig, L E

We have studied the temporal and spatial structures of UV and hard X-ray bursts in a disk ad a limb flare observed with instruments on the Solar Maximum Mission. The UV observations were spatially resolved with a resolution of 3''--4'' and were done in the Si IV, O IV lines and in the UV continuum region. The results are: (1) There was considerable preflare activity with UV transient brightenings occurring in many small point-like kernels. The flare later occurred in these active kernels; some of the active kernels, however, did not flare. (2) The impulsie UV and hard X-ray bursts were temporally correlated. Indivudual peaks in the hard X-ray bursts can be identified with individual peaks in the UV bursts of individual flaring kernels. In between the individual maxima, however, the UV emission remained intense. (3) There were impulsie brightenings in the UV continuum during the time of the hard X-ray bursts. (4) For the disk flare, the many flaring kernels were confined in a small area while for the limb flare, the impulsive bursts occurred in two points separated by a large distance of 50'' on the limb. (5)= The UV bursts started to rise earlier than the correspondig hard X-ray bursts. (6) There is some indication that the UV intensity of the bright points actually dropped just before it began to flare and to rise sharply. These results indicate that the emission source of the hard X-ray burst was located in the lower atmosphere where the density is high, and that there was local heating.

• Research Organization: E. O. Hulbert Center for Space Research, Naval Research Laboratory
• OSTI ID: 6747195
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 278:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CHARGED PARTICLES
ELECTROMAGNETIC RADIATION
EMISSION
HARD X RADIATION
IONIZING RADIATIONS
IONS
RADIATIONS
SILICON IONS
SOLAR ACTIVITY
SOLAR FLARES
SOLAR RADIATION
SOLAR X-RAY BURSTS
SPECTRA
STELLAR RADIATION
ULTRAVIOLET RADIATION
ULTRAVIOLET SPECTRA
X RADIATION
X-RAY SPECTRA