Our Solar is consistently lively, and far of its exercise, like Photo voltaic Flares and Coronal Mass Ejections, is pushed by its Magnetic Fields. Nonetheless, one can not immediately estimate this magnetic discipline; one must make use of varied observational and radio methods to estimate these magnetic fields (White 2004; Gopalswamy 2006). Whereas radio-based methods have been used to discover coronal magnetic fields in localised areas (e.g., utilizing band-splitting in kind II bursts; Smerd & Sheridan 1974), this research hyperlinks these early alerts from the Solar to in situ magnetic discipline measurements at 1 AU. This research might help in predicting how photo voltaic eruptions have an effect on the Earth’s setting. We utilised long-term information from photo voltaic cycles 23 and 24 to find out whether or not these radio alerts may present insights not solely into what is occurring close to the Solar but additionally into what may be coming towards Earth, significantly the Coronal Mass Ejections related to interplanetary coronal mass ejections (ICMEs).
This research recognized 88 metric kind II radio bursts linked to interplanetary CMEs (ICMEs) from photo voltaic cycles 23 and 24 (1997–2019), utilizing CME information from the CDAW catalogue (Yashiro et al. 2004) and ICME information from Richardson & Cane (2010). Radio observations had been primarily obtained from the RSTN community, with supplementary information from eCallisto and HiRAS (Kondo et al. 1995). Of those, 31 occasions confirmed split-band options, analysed utilizing dynamic spectra cleaned for interference and interpreted utilizing the four-fold Newkirk density mannequin (Newkirk 1961). Magnetic fields had been estimated utilizing the tactic talked about in Vršnak et al. (2002) and in contrast with in situ measurements at 1 AU from OMNI information through CDAWeb.
Determine 1: The left panel options radio information from the Learmonth Observatory, capturing a sort II photo voltaic burst that started at 08:24 UTC on July 6, 2006. The elemental and harmonic bands are highlighted utilizing the white-dashed traces. On the correct, LASCO C2 pictures taken at 09:06 and 10:06 UTC present the CME’s distinct three-part construction: core, cavity, and vanguard. This CME commenced at 08:54 UTC.
The 6 July 2006 kind II burst case (See Fig.1) revealed a CME pace of 911 km/s, a shock pace close to 369 km/s, and an ICME pace of 380 km/s (Richardson & Cane 2010). Coronal magnetic fields had been estimated at 0.45 G close to 1.4 R⊙ utilizing split-band radio information and the Newkirk mannequin (Kumari et al. 2019). Upstream magnetic fields at 1 AU had been about 4.5 × 10⁻⁵ G, in keeping with OMNI measurements. A research of 31 split-band occasions confirmed magnetic fields from 0.04 to 4.59 G between 1.1–2.5 R⊙, with a weak correlation (r = 0.14) between near-Solar and near-Earth magnetic fields. Shock heights and uncertainties had been derived utilizing Newkirk density fashions and CME propagation assumptions.
Conclusions
The research analysed 31 CME-ICME occasions utilizing split-band kind II radio bursts to estimate magnetic fields within the center corona. Statistical evaluation of radio parameters confirmed no constant linear correlation between near-Solar magnetic fields and people measured at 1 AU. This means metric radio information are unreliable for predicting magnetic discipline strengths close to Earth, seemingly as a consequence of complicated CME evolution by way of the heliosphere. Limitations embrace a scarcity of intermediate information between ~2 R☉ and 1 AU, which future missions like PSP and SolO could deal with. Velocity correlations stay promising for predictive insights.
Primarily based on the latest research by Kandekar, J. and Kumari, A., “On the restrictions of utilizing metric radio bursts as diagnostic instruments for interplanetary coronal mass ejections”, Astronomy and Astrophysics Letters, vol. 697, Artwork. no. L9, 2025. doi:10.1051/0004-6361/202553735.
References
Kumari, A., Ramesh, R., Kathiravan, C., Wang, T. J., & Gopalswamy, N. 2019, ApJ, 881, 24
Vršnak, B., Magdaleni´c, J., Aurass, H., & Mann, G. 2002, A&A, 396, 673
White, S. M. 2004, Astrophysics and House Science Library, 314, 89
Yashiro, S., Gopalswamy, N., Michalek, G., et al. 2004, J. Geophys. Res. House Phys., 109, A07105
