Characteristics of a type II solar radio burst on 22 March 1998 |
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Authors: | A Shanmugaraju S Umapathy V Balasubramanian |
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Institution: | (1) School of Physics, Madurai Kamaraj University, Madurai, 625 021, India;(2) TIFR, Radio Astronomy Centre, Udhagamandalam (Ooty), 643 001, India |
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Abstract: | A solar radio type II burst (which was seen as two patches of emission, one during 07:00–07:13 UT and other one during 07:20–07:35 UT)
was observed on 22 March 1998 using the Madurai radio spectrograph. A broad range of data (from Culgoora and Hiraiso spectrographs,
white-light data from SOHO/LASCO and X-ray data from Yohkoh and GOES satellites) was also studied for this event, which was analyzed in comparison with these supplementary data. In
addition, the conditions associated with this shock were analyzed quantitatively. From the above investigations, the following
conclusions have been made. The temporal relationship between H-alpha flare and burst has shown that the active region AR 8185
is the source of this type II burst. A bright front feature observed with LASCO is also associated with this type II burst
and active region AR 8185. The time profile of the shock derived from the first patch of this type II burst coincides with
the flare starting time. Also, within error limits, the start time of the CME is same as the flare. Hence, it is not possible
to decide whether the type II originated in the flare or was driven by CME. In addition, the investigations of the second
patch alone has provided the following results. The inferred shock speed for the second patch of emission is lower than the
first and closer to the CME speed. The emission occurred below 50 MHz. These conditions imply that this patch may be a separate
burst which might have been produced by the CME alone. |
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