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Session 19 - Solar Flares.
Oral session, Monday, June 10
Wisconsin Center,

[19.05] Temporal Variations of Solar Flare Spectral Properties in Ca \sc xix and GOES

A. C. Sterling (Computational Physics Inc., ISAS), H. S. Hudson (University of Hawai'i, ISAS), J. R. Lemen (Lockheed Martin Corp.), D. A. Zarro (Applied Research Corp.)

Since the advent of space borne X-ray observations, there has been a strong interest in the nature of the X-ray solar flare. Examining the relationships between radiations produced in different portions of the X-ray spectrum gives us information on the properties of the constituent flaring plasmas. We have studied the joint variation of electron temperatures and emission measures for a number of flares in two different wavelength ranges, using data from the narrow band Ca \sc xix channel (near 3.18 Åof the Bragg crystal spectrometer (BCS) experiment on board the Yohkoh spacecraft, and data from the wide band X-ray monitors on the Geostationary Operational Environmental Satellites (GOES, covering 0.5---8 ÅA power law relationship often describes the relationship between temperature and emission measure during the decay phase in both wavelength ranges. According to work of Sylwester et al.\ (1993, Aamp;A 267, 586), energy input parameters and physical properties of the flaring loop(s) determine the slope of this power law. We find that ratios of Ca \sc xix to GOES slopes generally fall between .6 and 1.0, when slopes in both channels are measured during the flare decay in each respective wavelength range. This relatively good agreement between slopes in the two channels suggests that emissions in both wavelength ranges originate from either the same flaring loop, or differing loops with similar global properties.

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