scholarly journals First Type III Solar Radio Bursts of Solar Cycle 25

Solar Physics ◽  
2021 ◽  
Vol 296 (4) ◽  
Author(s):  
Juha Kallunki ◽  
Derek McKay ◽  
Merja Tornikoski
Keyword(s):  
Solar Cycle ◽  
Solar Radio ◽  
Low Frequency ◽  
Radio Bursts ◽  
Solar Radio Bursts ◽  
Type Iii ◽  
Receiver Array ◽  
Imaging Receiver ◽  
Solar Bursts ◽  
Cycle 24

AbstractThe minimum of the previous solar cycle, Solar Cycle 24, occurred in December 2019, which also marked the start of the new Solar Cycle 25. The first radio bursts of the new solar cycle were observed in the spring season 2020. In this work we will present three type III solar bursts which were observed in May and June 2020 at radio frequencies between 18 – 90 MHz. There are two radio observatories in Finland that are capable of doing low-frequency solar radio observations: Aalto University Metsähovi Radio Observatory (MRO) and Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA) of the Sodankylä Geophysical Observatory, University of Oulu. The instruments of the two institutes have different design and characteristics, and they operate in rather different radio interference environments. We will compare simultaneous observations from these two instruments and we will also discuss the properties of these type III solar bursts.

On Low‐Frequency Type III Solar Radio Bursts Observed in Interplanetary Space

2004 ◽  
Vol 605 (1) ◽  
pp. 503-510 ◽  
Author(s):  
C. S. Wu ◽  
M. J. Reiner ◽  
P. H. Yoon ◽  
H. N. Zheng ◽  
S. Wang
Keyword(s):  
Solar Radio ◽  
Interplanetary Space ◽  
Low Frequency ◽  
Radio Bursts ◽  
Solar Radio Bursts ◽  
Type Iii

On the Fundamental and Harmonic Components of Low-Frequency Type III Solar Radio Bursts

1982 ◽  
Vol 4 (4) ◽  
pp. 382-386 ◽  
Author(s):  
S. Suzuki ◽  
K.V. Sheridan
Keyword(s):  
Solar Radio ◽  
Plasma Frequency ◽  
Low Frequency ◽  
Radio Bursts ◽  
Solar Radio Bursts ◽  
Type Iii ◽  
Field Lines ◽  
Harmonic Components ◽  
Electro Magnetic ◽  
Open Magnetic Field

Ground-based observations of Type III bursts made with spectrographs and spectro-polarimeters, at frequencies above the ionospheric cut-off, reveal that most bursts (excluding storm Type IIIs) have fundamental (F) and harmonic (H) structure (Wild et al. 1959; Dulk and Suzuki 1980). An example of F-H bursts is given by Sheridan (1978). Such bursts are produced by streams of electrons travelling along open magnetic field lines and exciting plasma oscillations which are converted to electro-magnetic waves at both the F and H frequencies of the local plasma frequency in the corona.

Exploring the circular polarisation of low-frequency solar radio bursts with LOFAR and estimating the coronal magnetic field

2021 ◽  
Author(s):  
Diana Morosan ◽  
Anshu Kumari ◽  
Juska Räsänen ◽  
Emilia Kilpua ◽  
Pietro Zucca ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Radio ◽  
Low Frequency ◽  
Coronal Magnetic Field ◽  
Plasma Emission ◽  
The Sun ◽  
Radio Bursts ◽  
Solar Radio Bursts ◽  
Circular Polarisation ◽  
Type Iii

<p>The Sun is an active star that often produces numerous bursts of electromagnetic radiation at radio wavelengths. In particular, low frequency (< 150 MHz)  radio bursts have recently been brought back to light with the advancement of novel radio interferometric arrays. However, the polarisation properties of solar radio bursts have not yet been explored in detail, especially with the Low Frequency Array (LOFAR). Here, we explore the circular polarisation of type III radio bursts and a type I noise storm and present the first Stokes V low frequency radio images of the Sun with LOFAR in tied array mode observations. We find that the degree of circular polarisation for each of the selected bursts increases with frequency for fundamental plasma emission, while this trend is either not clear or absent for harmonic plasma emission. In the case of type III bursts, we also find that the sense of circular polarisation varies with each burst, most likely due to their different propagation directions, despite all of these bursts being part of a long-lasting type III storm. Furthermore, we use the degree of circular polarisation of the harmonic emission of type III bursts to estimate the coronal magnetic field at distances of 1.4 to 4 solar radii from the centre of the Sun. We found that the magnetic field has a power law variation with a power index in the range 2.4-3.6, depending on the individual type III burst observed.</p>

scholarly journals Solar Radio Bursts at Low Frequencies

1974 ◽  
Vol 57 ◽  
pp. 183-200 ◽  
Author(s):  
J. Fainberg
Keyword(s):  
Solar Radio ◽  
Low Frequency ◽  
Leading Edge ◽  
Emission Region ◽  
The Sun ◽  
Radio Bursts ◽  
Solar Radio Bursts ◽  
Low Frequencies ◽  
Type Iii ◽  
Radio Measurements

Properties of solar radio bursts observed by spacecraft at frequencies below several MHz are reviewed. In this frequency range most of the observed bursts are type III events (associated with particles) but several cases of type II emission (associated with shocks) have been reported. The analyses which lead to emission levels of type III solar bursts out to beyond 1 AU from the Sun also indicate that the low frequency radiation is observed at the harmonic of the emission region plasma frequency. Simultaneous particle and radio measurements imply that the bursts are generated near the leading edge of impulsive streams of solar electrons with energies extending from several hundred keV to several keV. Recent experiments measuring the direction of arrival of the radio emission allow the exciter particles to be tracked along the interplanetary magnetic field from regions near the Sun out to 1 AU.

Electron Exciter Speeds Associated with Interplanetary Type III Solar Radio Bursts

Solar Physics ◽  
2015 ◽  
Vol 290 (10) ◽  
pp. 2975-3004 ◽  
Author(s):  
M. J. Reiner ◽  
R. J. MacDowall
Keyword(s):  
Solar Radio ◽  
Radio Bursts ◽  
Solar Radio Bursts ◽  
Type Iii
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