An analytical study of type III bursts (Bonnin 2008b) observed by the Wind/Waves instrument have also discovered an optimum reaction of type III bursts at around 1 MHz formerly reported by Weber (1978 ). In this article, we have actually studied the spectral action of the type III bursts over a much wider bandwidth (i.e., 20 kHz– 410 MHz) and discovered that the maximum spectral action lies between 1 and 2 MHz.
We have actually studied 1434 type III bursts that were observed by Wind/Waves entirely and 115 type III bursts that were observed all at once by both Wind/Waves and NDA. The leading panel reveals the observation of type III bursts carried out utilizing the NDA in the frequency range 10– 80 MHz. In this post, we present the analytical analysis of the spectral reaction of solar radio type III bursts over the broad frequency range between 20 kHz and 410 MHz.
Figure 2– Spectral response of type III bursts observed from 20 kHz to 410 MHz is shown. The yellow circle, magenta cross, and blue plus markers show the maximum flux density (in SFU) of the 115 type III bursts observed utilizing RAD1 and RAD2 receivers of the Wind/Waves instrument and Nançay Decameter Array, respectively. The orange asterisk markers suggest the observations of Nançay Radioheliograph at chosen frequencies (i.e., 164, 236, 327, and 410 MHz). The black solid curve represents the mean (i.e., 50th percentile) of the flux densities of the data displayed in every frequency channel. The red filled area shows the very first and third quartiles of the data shown. Note that the galactic contribution is deducted.
Conclusions
In this short article, we provide the statistical analysis of the spectral response of solar radio type III bursts over the wide frequency range between 20 kHz and 410 MHz. The primary outcome of our research study is that type III bursts, in the metric to hectometric wavelength range, statistically show a clear optimum of their mean radio flux density around 2 MHz. Utilizing the Sittler and Guhathakurtha model for coronal streamers, we have actually discovered that the maximum of radio power for that reason falls in the variety of ~ 3 to ~ 20 solar radii, depending on whether the type III emissions are presumed to be at the essential or the harmonic.
Based on the recently published post: K. Sasikumar Raja, et al, “Spectral Analysis of Solar Radio Type III Bursts from 20 kHz to 410 Mhz”, The Astrophysical Journal, 924( 2 ):58, January 2022. doi:10.3847/ 1538-4357/ ac34ed.
Recommendations
1. Bonnin, X. 2008b, PhD thesis, Université Paris-Diderot– Paris VII, https:// hal.archives-ouvertes. fr/tel -00461521.
2. Krupar, V., Maksimovic, M., Santolik, O., et al. 2014, SoPh, 289, 3121.
3. Weber, R. R. 1978, SoPh, 59, 377.
* Full list of authors: K. Sasikumar Raja, Milan Maksimovic, Eduard P. Kontar, Xavier Bonnin, Philippe Zarka, Laurent Lamy, Hamish Reid, Nicole Vilmer, Alain Lecacheux, Vratislav Krupar, Baptiste Cecconi, Lahmiti Nora, and Laurent Denis.
Type III bursts wander from high frequency (~ 1 GHz) to 20 kHz at 1 AU and in some cases even beyond. A statistical research study of type III bursts (Bonnin 2008b) observed by the Wind/Waves instrument have likewise found an optimum action of type III bursts at around 1 MHz formerly reported by Weber (1978 ). In this post, we have studied the spectral reaction of the type III bursts over a much larger bandwidth (i.e., 20 kHz– 410 MHz) and discovered that the maximum spectral response lies in between 1 and 2 MHz.
Observations
In this article, we have actually performed the first-ever statistical analysis of the spectral reaction of solar-type III bursts over the large frequency range in between 20 kHz and 410 MHz. For this function, we have used the observations that were performed utilizing both spaced-based (Wind/Waves) and ground-based (NDA, Nançay Decameter Array and NRH, Nançay Radioheliograph) centers. In order to compare the flux densities observed by the different instruments, we have actually thoroughly calibrated the data and displayed them in solar flux systems (SFU). We have actually studied 1434 type III bursts that were observed by Wind/Waves solely and 115 type III bursts that were observed simultaneously by both Wind/Waves and NDA. Note that in the latter case, both instruments observed type III bursts that were approximately in the exact same view. In addition, we have included the information derived using adjusted observations of the NRH at some particular frequencies.
The top panel reveals the observation of type III bursts brought out utilizing the NDA in the frequency range 10– 80 MHz. We keep in mind that a type III burst at 13:30 UT is not seen in RAD2 due to the fact that of missing out on information.
Outcomes
The main outcomes of our research study is that type III bursts in the metric to hectometric wavelengths range statistically exhibit an optimum of their radio power at around 1 to 2 Mhz as displayed in Figure– 2. Utilizing the Sittler and Guhathakurtha design for coronal banners, we have found that this frequency range corresponds to the heliocentric distance range ≈ 3– 8 solar radii if one presume a radio emission at the essential plasma frequency. On the other hand if the type III bursts are a mix of both harmonic and essential emissions, the optimum of the radio flux would originate in the heliocentric distance series of ~ 3 to ~ 20 solar radii. Keep in mind that this radial range is essential for the solar wind since this is where it becomes both supersonic, after the Parker sonic point, and super-Alfvénic.
There is no doubt that our findings will soon be compared to in situ observations. The Parker Solar Probe is expected to reach 10 solar radii in 2024. The in-situ measurements of the various plasma specifications including density changes, Langmuir waves, and energetic electrons should provide important information for fully explaining the optimum radio flux of solar type III bursts.
