News Update Viral

Photo voltaic radio spikes can present detailed details about plasma processes in photo voltaic flares on kinetic scales. Amongst them, the decimeter peaks belong to probably the most attention-grabbing as a result of they’re recorded in some instances near the onset frequency of sort III bursts and associated to laborious X-ray emissions.

Stepanov et al. (1999) Y Barta and Karlicky (2001) offered fashions the place the frequencies of the peaks correspond to these of the higher hybrid waves, and Willes and Robinson (1996) offered the mannequin with frequency peaks comparable to the Bernstein modes. Luoo et al. (2021) proposed that the peaks are generated within the termination shock fashioned above the flare arcade, the place a diffuse supraarcade fan and multitude of downward plasma flows are current. This interpretation is near the concept that narrowband dm peaks are generated by superthermal electrons in magnetohydrodynamic turbulence in magnetic reconnection outflows. (Karlický, Sobotka and Jiřička, 1996).

There may be an extra essential side of narrowband dm peaks that’s not usually thought-about in theoretical fashions. That’s, peaks seem within the frequency bands and the band frequency ratio will not be an integer (1.06 – 1.54) (Krucker and Benz 1994). Within the position of Karlický, Benáček and Rybák (2021), This end result was not solely confirmed, however very slender bands of spikes within the occasion of November 7, 2013, allowed a profitable adjustment of the band frequencies by Bernstein modes.

Observations

We investigated the peaks noticed throughout the flare on June 13, 2012 with an Ondřejov radio spectrograph from 800-2000 MHz with a time decision of 0.01 s and a frequency decision of 4.7 MHz. As well as, we analyzed the connection between the radio and X-rays AIA/SDO UV, HMI/SDO and RHESSI.

The radiospectrogram is proven in Determine 1, and the numbered peak occasions are labeled in Desk 1 into three classes in accordance with their look within the radio spectrum: peaks distributed in a band or broad bands (SB), peaks distributed in bands sort zebra ( SZ), and peaks distributed in broad and slender bands (SBN). The attribute proportions of neighboring peaks are decided if a couple of band seems. Examples of peak sorts are proven in Determine 2.

Determine 1. The radio spectrum noticed at 13:10:00 – 13:30:00 UT throughout the flare on June 13, 2012 by the Ondřejov radio spectrograph.

Desk 1. Fundamental parameters of peak teams throughout the flare in Determine 1: occasions, frequency vary, sorts, most variety of frequency bands (MNFB) and attribute relationships of peak neighbor bands (BR).

Determine 2. Peaks noticed throughout the eruption of June 13, 2012. The radio spectrum exhibits peaks distributed in a) broad band(s) (SB), b) zebra-like bands (SZ), and c) broad and slender bands ( SBN).

Conclusions

We verify that the dm peaks are primarily noticed throughout the impulsive flash part. We tried to seek for any relationship between peak clusters and depth variations at chosen flare areas utilizing AIA/SDO observations. We discovered an attention-grabbing relationship for AIA intensities taken from one finish of the sigmoidal flash construction the place many flash loop magnetic subject strains had been concentrated.

We discover that related autocorrelations of SZ and SBN favor the identical mechanism of technology of those peaks. Due to its similarity to Karlický et al. (2021)we interpret SZ and SBN generated in Bernstein modes. We assist this interpretation by simulations of the Bernstein modes.

We examine the Kind SZ and a zebra noticed on August 1, 2010 in the identical frequency vary. We discovered some variations:

• The separation frequency is about 220 MHz within the SZ case, whereas in zebras it’s about 24 MHz,
• The variability of autocorrelation over time is considerably larger for zebras than for the SZ sort,
• The ratios between the SZ peak bands are (4.4, 5.1, 6.0, 7.0) and (4.0, 4.9, 6.0), whereas for zebras it’s ~52,
• The separation frequency of neighboring zebra stripes modifications in numerous methods for various pairs. This behaviour excludes the opportunity of zebras spawning at an emission supply, in addition to the SZ sort peaks by Bernstein modes.

In accordance with our earlier concepts (Bárta and Karlický, 2001)we conclude that SZ and SBN are fashioned in in a magnetic reconnection exit area, the place the plasma is in a turbulent state. Utilizing the Bernstein mannequin, we estimate the imply magnetic subject energy and plasma density within the SZ supply to be roughly 79 G and $8.4×10^9 cm⁻¹, respectively.

Primarily based on a latest article by Karlicky et al.,’Narrowband spikes noticed throughout the June 13, 2012 flare within the 800-2000 MHz vary‘, Photo voltaic Physics 297:54 (2022), DOI: https://doi.org/10.1007/s11207-022-01989-4

References

Bárta, M. and Karlický, M. 2001, A&A, 379, p. 1045-1051.

Karlický, M., Sobotka, M., and Jiřička, Ok. 1996, solar. Phys., 168, 2.

Karlický, M., Benáček, J., and Rybák, J., 2021, ApJ, 910, 2.

Krucker, S. and Benz, AO, 1994, A&A, 285, p. 1038-1046.

Luo Y, Chen B, Yu S, Bastian, et al. 2021, ApJ, 911, 1.

Stepanov AV, Kliem B, Krüger A, et al. 1999, ApJ, 524, 2.

Willes, A.J. and Robinson, Pennsylvania 1996, ApJ, 467, 465.