J/A+A/618/A165 Solar type III radio burst (Zhang+, 2018)
A type III radio burst automatic analysis system and statistic results for
a half solar cycle with the Nancay Decameter Array data.
Zhang P.J., Wang C.B., Ye L.
<Astron. Astrophys. 618, A165 (2018)>
=2018A&A...618A.165Z 2018A&A...618A.165Z (SIMBAD/NED BibCode)
ADC_Keywords: Sun
Keywords: Sun: radio radiation - Sun: activity - plasmas -
methods: data analysis - techniques: image processing
Abstract:
We design an event recognition-analysis system that can automatically
detect solar type III radio burst and can mine information of the
burst from the dynamic spectra observed by Nancay Decameter Array
(NDA). We investigate the frequency drift rate of type III bursts and
the speed of electron beams responsible for the generation of the
bursts.
Several computer vision methods are used in this automatic analysis
system. The Hough transform is performed to recognize the line segment
associated with type III bursts in the dynamic spectra. A modified
active contour model is used to track the backbone of the burst and
estimate the frequency drift rate at different frequency channels. We
run this system on the NDA data from 2012 to 2017, and give a
statistical survey of the event number distribution, the starting and
stopping frequencies of bursts, the frequency dependence of the drift
rate, and the exciter speed using three corona density models.
The median value of the average frequency drift rates is about
6.94MHz/s for 1389 simple well-isolated type III bursts detected in
the frequency range 10-80MHz of NDA observation. The frequency drift
rate changes with frequency as df/dt=-0.0672f1.23 from a
least-squares fitting. The average exciter speed is about 0.2c based
the density models. We do not find any significant dependence of the
drift rate and the exciter speed on the solar activity cycle.
Description:
The table contains 1389 records, each record includes the event
observation time, the starting/stopping frequencies and the average
frequency drift rate of a type III solar radio burst. The events were
observed by The Nancay Decameter Array (NDA) in the frequency range
10-80MHz between 2012 and 2017.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table.dat 52 1389 Frequency range and frequency drift rate of
solar type III bursts
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See also:
J/A+AS/119/489 : Solar Type II Radio Bursts, 1990.09 - 1993.12 (Mann+ 1996)
J/ApJ/710/L58 : Coronal type II radio bursts in 2002 (Lobzin+, 2010)
Byte-by-byte Description of file: table.dat
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Bytes Format Units Label Explanations
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1- 20 A20 "date" Obs.date Observation date (DD-MMM-YYYY hh:mm:ss)
26- 31 F6.3 MHz fstop Stopping frequency of the event
37- 42 F6.3 MHz fstart Starting frequency of the event
46- 52 F7.3 MHz/s FDR Average frequency drift rate
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Acknowledgements:
C.B. Wang, cbwang(at)ustc.edu.cn
P.J. Zhang, pjer1316(at)mail.ustc.edu.cn
(End) Patricia Vannier [CDS] 20-Aug-2018