Evaluating Mean Magnetic Field in Flaring Loops |
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Jiong Qiu Submitted: 2009-01-07 11:10
We analyze multiple-wavelength observations of a two-ribbon flare exhibiting apparent expansion motion of the flare ribbons in the lower atmosphere and rising motion of X-ray emission at the top of newly formed flare loops. We evaluate magnetic reconnection rate in terms of V
m rB
m r by measuring the ribbon expansion velocity (V
m r)
and the chromospheric magnetic field (B
m r) swept by the ribbons. We also measure the velocity (V
m t) of the apparent rising motion of the loop top X-ray source, and estimate the mean magnetic field (B
m t) at the top of newly formed flare loops using the relation langle V
m tB
m t
angle approx langle V
m rB
m r
angle, namely, conservation of reconnection flux along flare loops. For this flare, B
m t is found to be 120 and 60~G, respectively, during two emission peaks five
minutes apart in the impulsive phase. An estimate of the magnetic field in flare loops is also achieved by analyzing the microwave and hard X-ray spectral observations, yielding B = 250 and 120~G at the two emission peaks, respectively. The measured B from the microwave spectrum is an appropriately weighted value of magnetic field from
the loop top to the loop leg. Therefore, the two methods to evaluate coronal magnetic field in flaring loops produce fully consistent results in this event.
Authors: Qiu, J., Gary, D. E., Fleishman, G. D.
Projects:
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Publication Status: Solar Physics, 255, 107
Last Modified: 2009-02-24 19:12
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