AAS Meeting #194 - Chicago, Illinois, May/June 1999
Session 54. Solar Flares
Display, Tuesday, June 1, 1999, 10:00am-7:00pm, Southeast Exhibit Hall

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[54.02] Tests of the Temperature Dependence of the Neupert Effect in Solar Flares

J. M. McTiernan (Space Sciences Lab, Univ. of California)

It is well known that the time derivative of the soft X-ray light curve for a solar flare is similar to the time profile of the impulsive hard X-ray emission for the flare. This is called the Neupert effect. It is less well known that the degree of consistence with the Neupert effect is different for different soft X-ray detectors. In particular, a detector with a response to radiation from high temperature plasma, such as the Yohkoh BCS, is much more likely to exhibit the Neupert effect than a wavelength band with a response to radiation from low temperature plasma, such as the Yohkoh SXT.

In this study, a simple correlation technique is used to determine whether the soft X-ray time derivative is similar to the hard X-ray light curve for each flare of a large sample of flares. In order to compare the degree of consistence with the Neupert effect at different temperatures, data from the FeXXV band of the Yohkoh BCS, and the Al.1 filter of the Yohkoh SXT are used in comparison with data from the Yohkoh HXT. The results are then compared to those obtained by comparing the soft X-ray curves to random samples of the hard X-ray curves.

For example, preliminary results for a sample of 137 flares show that high temperature radiation, as seen in the BCS-FeXXV channel is consistent with the Neupert effect for 47 of the flares. This is approximately twice the number of flares that would show consistence from a random sample. For low temperature radiation, as seen by the SXT-Al.1 filter, only 10 of the 137 flares are consistent with the Neupert effect, which is the same number as would be expected from a random sample. This work was supported by NASA grant NAGW-5126 and Lockheed subcontract LMSC-SA30G4740R.

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