Extreme-ultraviolet spectrum of a solar impulsive burst

Journal Article · Thu Jul 15 04:00:00 EDT 1982 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/160130· OSTI ID:6849421

Widing, K G

The spectrum of the 1973 December 22 flare in the 170--345 A range is presented as an example of a class of impulsive EUV events observed with the NRL spectroheliograph on Skylab. The spectrum shows strongly enhanced emission of He II and transition-zone ions. A number of new solar identifications of N IV, O IV, and O V are given. New density diagnostics for the O V 192, 215, and 220 A lines have been developed and applied. The transition-zone emission measure shows an unusually flat slope proportionalT/sup 0.8/. The EUV emission has a fine-scale structure of the order of 2 km in O IV and O V and 60 km in Fe IX and Si X. The unresolved fine structure could represent a collection of filaments, or alternatively, thin layers produced by sharp temperature gradients along a loop. For simple assumptions on the energy balance, the small transition-zone thickness and the approximate slope of the emission measure distribution are reproduced.

• Research Organization: E. O. Hulburt Center for Space Research, US Naval Research Laboratory, Washington, DC
• OSTI ID: 6849421
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 258:2; 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
EXTREME ULTRAVIOLET RADIATION
FUNCTIONS
IONS
NITROGEN IONS
OXYGEN IONS
RADIATIONS
SOLAR ACTIVITY
SOLAR FLARES
SPECTRA
SPECTRAL FUNCTIONS
ULTRAVIOLET RADIATION
ULTRAVIOLET SPECTRA