Solar radio pulsations at 410 MHz |
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Authors: | C S Wright G J Nelson |
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Institution: | (1) Department of Science, IPS Radio and Space Services, P.O. Box 702, 2010 Darlinghurst, N.S.W., Australia;(2) Present address: Radiowave Propagation Group, DRCS, GPO Box 2151, 5001 Adelaide, S.A., Australia;(3) Division of Radiophysics, C.S.I.R.O., P.O. Box 76, 2121 Epping, N.S.W., Australia |
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Abstract: | On 6 September, 1982 very regular, narrow-band radio pulsations of solar origin were observed on the 410 MHz solar radiometer at the Learmonth Solar Observatory. Initial low-amplitude pulsations with a period of about 3 min gave way to large-amplitude pulsations with a period of about 5 min following a 1B solar flare. Position measurements at 327 MHz with the Culgoora Radioheliograph indicated two sources: a strong, extended source located above a unipolar magnetic region near the centre of the disk and a much weaker source near the west limb. Polarisation measurements indicate the burst to be plasma emission.The radio pulsations were unique in their association with both sympathetic radio emission and optical flares at widely different locations. Interpretation of the observations in terms of sausage mode standing oscillations in a coronal flux tube leads to an estimate of the magnetic flux density B = 45 G at the 400 MHz plasma level. Also a 2.8-fold density increase in the loop after the 1B flare is inferred. |
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