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Astronomy & Astrophysics
Polarisation and source structure of solar stationary type IV radio bursts2020 •
The reconfiguration of the magnetic field during and after a coronal mass ejection (CME) may be accompanied by radio emission from non-thermal electrons. In particular, stationary type IV bursts (also called storm continua) are emitted by electrons in closed magnetic configurations usually located in the wake of the outward-travelling CME. Although stationary type IV bursts, which stand out by their long duration (up to several hours) and strong circular polarisation, have been known for more than fifty years, there have been no systematic studies since the 1980s. In this work we use the data pool of the Nançay Radioheliograph together with white-light coronagraphy, EUV imaging and magnetography from the SoHO, Proba2, SDO and STEREO spacecraft to revisit the source structure and polarisation of a sample of seven well-defined stationary type IV bursts at decimetre-to-metre wavelengths. The radio sources are most often found in one leg, in one case both legs, of the magnetic flux rope...
The Astrophysical Journal
Fine Structures of Solar Radio Type III Bursts and Their Possible Relationship with Coronal Density Turbulence2018 •
Solar radio type III bursts are believed to be the most sensitive signatures of near-relativistic electron beam propagation in the corona. A solar radio type IIIb-III pair burst with fine frequency structures, observed by the Low Frequency Array (LOFAR) with high temporal (∼10 ms) and spectral (12.5 kHz) resolutions at 30-80 MHz, is presented. The observations show that the type III burst consists of many striae, which have a frequency scale of about 0.1 MHz in both the fundamental (plasma) and the harmonic (double plasma) emission. We investigate the effects of background density fluctuations based on the observation of striae structure to estimate the density perturbation in the solar corona. It is found that the spectral index of the density fluctuation spectrum is about −1.7, and the characteristic spatial scale of the density perturbation is around 700km. This spectral index is very close to a Kolmogorov turbulence spectral index of −5/3, consistent with a turbulent cascade. This fact indicates that the coronal turbulence may play the important role of modulating the time structures of solar radio type III bursts, and the fine structure of radio type III bursts could provide a useful and unique tool to diagnose the turbulence in the solar corona.
2018 •
International Letters of Chemistry, Physics and Astronomy
Detailed Investigation of a Moving Solar Burst Type IV Radio Emission in on Broadband Frequency2014 •
The moving type IV burst component of the solar radio region from 260-380 MHz observed using the CALLISTO spectrometer is discussed in detail. We used the Compound Astronomical Low Cost Low Frequency Spectrometer Transportable Observatory (CALLISTO) system connected to the Log Periodic Dipole Antenna (LPDA) at the National Space Centre, Selangor located (3.0833333°N 101.5333333°E) on 22nd February 2012. It is found that a strong burst that caused by extraordinary solar flares are due to magnetic reconnection effect potentially induced in the near-Earth magneto tail. From our observation the indication of signal potentially drives Coronal Mass Ejections (CMEs). We also compare our results with the Geostationary Operational Environmental Satellites (GOES) data. From our analysis, one possible reason behind the formation of this very complex long duration of this loop is the magnetic reconnection and disruption of the loops which is observed during flare maximum. The Active Region, AR ...
The Astrophysical Journal
The origin of the modulation of the radio emission from the solar corona by a fast magnetoacoustic wave2018 •
Observational detection of quasi-periodic drifting fine structures in a type III radio burst associated with a solar flare SOL2015-04-16T11:22, with Low Frequency Array, is presented. Although similar modulations of the type III emission have been observed before and were associated with the plasma density fluctuations, the origin of those fluctuations was unknown. Analysis of the striae of the intensity variation in the dynamic spectrum allowed us to reveal two quasi-oscillatory components. The shorter component has the apparent wavelength of ∼ 2 Mm, phase speed of ∼ 657 km s −1 , which gives the oscillation period of ∼ 3 s, and the relative amplitude of ∼ 0.35%. The longer component has the wavelength of ∼ 12 Mm, and relative amplitude of ∼ 5.1%. The short frequency range of the detection does not allow us to estimate its phase speed. However, the properties of the shorter oscillatory component allowed us to interpret it as a fast magnetoacoustic wave guided by a plasma non-uniformity along the magnetic field outwards from the Sun. The assumption that the intensity of the radio emission is proportional to the amount of plasma in the emitting volume allowed us to show that the superposition of the plasma density modulation by a fast wave and a longer-wavelength oscillation of an unspecified nature could readily reproduce the fine structure of the observed dynamic spectrum. The observed parameters of the fast wave give the absolute value of the magnetic field in the emitting plasma of ∼ 1.1 G which is consistent with the radial magnetic field model.
Astronomy & Astrophysics
Observation of quasi-periodic solar radio bursts associated with propagating fast-mode waves2016 •
Biology and Life Sciences Forum
Enhancing Sorghum Productivity with Methyur, Kamethur, and Ivin Plant Growth RegulatorsRevista Brasileira de Enfermagem
The multidimensional model of hope as a recovery-focused practice in mental health nursing2022 •
The Role Of Societal Expectations In The Development Of Self-Critical Tendencies
The Role Of Societal Expectations In The Development Of Self-Critical Tendencies2023 •
Oxford Research Encyclopedia of Education
The Indonesian Equivalency Program for Out-of-School Youth2020 •
Journal of Plant Protection Research
Study on Biology of Onion Thrips, Thrips Tabaci Lindeman (Thysanoptera: Thripidae) on Cucumber (Var. Sultan) in Laboratory Conditions2009 •
2020 •
Revista de Enfermagem UFPE on line
Proposta de um modelo de capacitação para implantação da sistematização da assistência de enfermagem: pesquisa-ação2012 •
Vestnik Ûžno-Uralʹskogo gosudarstvennogo universiteta
Justification of Technology of Hemp Milk Production and Evaluation of Its Nutritional and Biological Value2019 •
Frontiers in Cell and Developmental Biology
Unconventional Protein Secretion in Brain Tumors Biology: Enlightening the Mechanisms for Tumor Survival and ProgressionScientific reports
Multilocus phylogenetic analyses reveal unexpected abundant diversity and significant disjunct distribution pattern of the Hedgehog Mushrooms (Hydnum L.)2016 •
Current Directions in Biomedical Engineering
A pilot study: development of bonepreserving- biomimetic artificial femoral head cover2020 •