Harmonics of Solar Radio Spikes at Metric Wavelengths
This paper presents the latest observations from the newly built solar radio spectrograph at the Chashan Solar Observatory. On July 18, 2016, the spectrograph records a solar spike burst event, which has several episodes showing harmonic structures, with the second, third, and fourth harmonics. The lower harmonic radio spike emissions are observed later than the higher harmonic bands, and the temporal delay of the second (third) harmonic relative to the fourth harmonic is about 30 – 40 (10) ms. Based on the electron cyclotron maser emission mechanism, we analyze possible causes of the temporal delay and further infer relevant coronal parameters, such as the magnetic field strength and the electron density at the radio source.
KeywordsRadio burst Dynamic spectrum Radio spike Electron cyclotron maser emission
We thank Valentin Melnik for valuable suggestions made to improve the quality of this manuscript. The authors gratefully acknowledge the teams of RSTN and ORFEES for making their data available to us. This work was supported by grants NNSFC-CAS U1431103, and NNSFC 41331068, 11790303 (11790300), 11503014, 41504131, 11703017, NSF of Shandong Province (ZR201702100072, ZR2016AP13), and was supported by the Specialized Research Fund for the State Key Laboratories.
Conflict of interest
The authors declare that they have no conflicts of interest.
- Bouratzis, C., Hillaris, A., Alissandrakis, C.E., Preka-Papadema, P., Moussas, X., Caroubalos, C., Tsitsipis, P., Kontogeorgos, A.: 2015, Fine structure of metric Type IV radio bursts observed with the ARTEMIS-IV radio-spectrograph: association with flares and coronal mass ejections. Solar Phys. 290, 219. DOI. ADS. ADSCrossRefGoogle Scholar
- Bouratzis, C., Hillaris, A., Alissandrakis, C.E., Preka-Papadema, P., Moussas, X., Caroubalos, C., Tsitsipis, P., Kontogeorgos, A.: 2016, High resolution observations with Artemis-IV and the NRH. I. Type IV associated narrow-band bursts. Astron. Astrophys. 586, A29. DOI. ADS. ADSCrossRefGoogle Scholar