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The Highlights of Solar Radio Physics (science nuggets) are short communications written in the language accessible to a non-expert in the specific area. The nugget is a brief description of a new and interesting scientific result, not as detailed as a scientific article, but rather written in a more discursive ‘news & views’ style.

CESRA
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• January 31, 2017
• 07:06 AM
• 573 views

# Emission of radiation by plasmas with counter-streaming electron beams by L. F. Ziebell et al.*

The phenomena of emission of radiation by the Sun, which are known as type II and type III solar radio bursts, have been known and investigated for more than sixty years. The bursts of radiation occur at a frequency corresponding to the plasma frequency at the source region, and harmonics [...]... Read more »

Ziebell, L., Petruzzellis, L., Yoon, P., Gaelzer, R., & Pavan, J. (2016) PLASMA EMISSION BY COUNTER-STREAMING ELECTRON BEAMS. The Astrophysical Journal, 818(1), 61. DOI: 10.3847/0004-637X/818/1/61

• October 18, 2016
• 09:02 AM
• 566 views

# Decameter type III bursts with changing frequency drift-rate signs by V. Melnik et al.*

We discuss properties of type III bursts that change the sign of their drift rate from negative to positive and vice versa. Moreover, these bursts may change the sign of their drift rates more than once. These particular type III bursts were observed simultaneously by the radio telescopes UTR-2, URAN-2, [...]... Read more »

V. Melnik et al. (2015) Decameter type III bursts with changing frequency drift-rate signs . Solar Physics. info:/

• October 4, 2016
• 09:05 AM
• 564 views

# Propagation of Coronal Mass Ejections: Aerodynamic Drag by Nishtha Sachdeva and Prasad Subramanian

Coronal Mass Ejections (CMEs) are hot, massive blobs of plasma and magnetic fields that erupt from the Sun, and are sometimes Earth-directed. Depending on their speed and mass these transients can strongly effect the space weather, causing geomagnetic storms and damage to space bound technologies. It is therefore imperative to [...]... Read more »

Sachdeva, N., Subramanian, P., Colaninno, R., et al.,. (2015) Propagation of Coronal Mass Ejections: Aerodynamic Drag. Astrophysical Journal, 158. info:/

• September 13, 2016
• 09:02 AM
• 541 views

# An Analysis of Interplanetary Solar Radio Emissions Associated with a Coronal Mass Ejection by V. Krupar et al.*

Type II and type III bursts are generated, via the plasma emission mechanism, when beams of suprathermal electrons interact with the ambient plasma generating radio emissions at the plasma frequency fp (the fundamental emission) or at its second harmonic 2fp (the harmonic emission) [see also previous CESRA highlights here and [...]... Read more »

V. Krupar et al. (2016) An Analysis of Interplanetary Solar Radio Emissions Associated with a Coronal Mass Ejection. Astrophys. J. Lett., 823, L5. info:/

• November 1, 2016
• 09:01 AM
• 541 views

# Multiwavelength study of 20 jets that emanate from the periphery of active regions by Sargam M. Mulay et al.*

Solar jets are transient phenomena observed in the solar atmosphere. They appear as sharp-edged, impulsive, and collimated flows of plasma that move outwards with a bright spot at the footpoint, which forms an ‘inverted-Y’ topology of magnetic field lines. They are observed throughout the atmosphere i.e. in the photosphere (Hα, Ca II K [...]... Read more »

Mulay et al. (2006) Multiwavelength study of 20 jets that emanate from the periphery of active regions. Astronomy . info:/

• December 13, 2016
• 08:23 AM
• 490 views

# Acceleration of electrons in the solar wind by Langmuir waves produced by a decay cascade by Catherine Krafft and Alexander Volokitin

It was recently reported that a significant part of the Langmuir waveforms observed by the STEREO satellite (Graham and Cairns, 2013) during type III solar radio bursts are likely consistent with the occurrence of electrostatic decay instabilities, when a Langmuir wave $$\mathcal{L}$$ resonantly interacts with another Langmuir wave $$\mathcal{L}^{\prime}$$ and [...]... Read more »

• September 6, 2016
• 01:00 PM
• 479 views

# High resolution observations of radio noise storms in the solar corona

The solar corona is a well known site for particle acceleration – examples range from spectacular large flares to the hard-to-observe nanoflares that are now a leading candidate for coronal heating.... Read more »

Prasad Subramanian and Claude Mercier. (2016) High resolution observations of radio noise storms in the solar corona . Astronomy . info:/

• November 22, 2016
• 07:03 AM
• 473 views

# Energetic electrons generated during solar flares by Gottfried Mann

The Sun is an active star. It manifests not only in everybody’s well-known Sun spots with the related 11-year cycle. This activity manifests not only as the well-known sun spot phenomenon with a related 11-year cycle, but also in flares, coronal mass ejections (CMEs), and solar energetic particle (SEP) events. Thus, [...]... Read more »

Gottfried Mann. (2016) Energetic electrons generated during solar flares. Journal of Plasma Physics. info:/

• December 20, 2016
• 07:02 AM
• 448 views

# Diagnosing the Source Region of a Solar Burst on 26 September 2011 by Using Microwave Type-III Pairs by Tan B. L. et al.*

Accelerated electron beams are believed to be responsible for both hard X-ray (HXR) and strong coherent radio emission during solar flares. However, so far the location of the electron acceleration and its physical parameters are poorly known. The solar microwave Type-III pair burst is possibly the most sensitive signature of [...]... Read more »

• November 29, 2016
• 07:02 AM
• 445 views

# Simultaneous Submillimeter and Hard X-Ray Intermittent Processes during Flares by Guillermo Giménez de Castro et al.*

Intermittency is a disruptive characteristic of a process, which can be associated, in many cases, with a sudden energy release. Intermittency is a key characteristic of flares that should become evident in the flux time evolution at many different wavelengths. We investigate the similarities and differences of the intermittency during [...]... Read more »

• August 23, 2016
• 09:02 AM
• 437 views

# Bright 30 THz impulsive solar bursts by Pierre Kaufmann et al.*

Impulsive 30 THz continuum bursts have been recently observed in solar flares, utilizing small telescopes with a unique and relatively simple optical setup concept (Kaufmann et al. 2015). The most intense burst was observed together with a GOES X2 class event on October 27, 2014, also detected at two sub-THz [...]... Read more »

Pierre Kaufmann et al. (2016) Bright 30 THz impulsive solar bursts . Journal of Geophys. Res. info:/

• November 15, 2016
• 07:05 AM
• 435 views

# Solar Type III Radio Bursts: Directivity Characteristics by G. Thejappa and R. J. MacDowall

Type III radio bursts are a group of fast drifting radio emissions associated with solar flares [see also previous CESRA highlights on type III bursts here and here]. These radio emissions are believed to be excited at the fundamental and second harmonic of the electron plasma frequency, by the electron beam excited Langmuir waves [...]... Read more »

G. Thejappa and R. J. MacDowall. (2015) Solar Type III Radio Bursts: Directivity Characteristics . Journal of Physics: Conference Series. info:/

• August 30, 2016
• 09:04 AM
• 433 views

# On the thermal nature of 140 GHz emission from the 4 July 2012 solar flare by Yuriy Tsap et al.*

The nature of the solar flare sub-THz emission (Kaufmann, 2012) with a positive spectral slope at 200-400 GHz is still not clear..... Read more »

Yuriy Tsap et al.*. (2016) On the thermal nature of 140 GHz emission from the 4 July 2012 solar flare. Advances in Space Research, 2016, 57, 1449. info:/

• August 9, 2016
• 09:24 AM
• 425 views

# Particle Acceleration and heating by turbulent reconnection by L. Vlahos, T. Pisokas, H. Isliker, V. Tsiolis and A. Anastasiadis

Fermi (1949) introduced a fundamental stochastic process to solve the problem of particle energization (heating and/or acceleration) in space and astrophysical plasmas. The initial idea of Fermi with randomly moving scatterers (magnetic clouds), was soon replaced with a spectrum of low amplitude (δΒ/Β... Read more »

by L. Vlahos, T. Pisokas, H. Isliker, V. Tsiolis and A. Anastasiadis. (2016) Particle Acceleration and heating by turbulent reconnection. ApJ. info:/

• December 6, 2016
• 07:08 AM
• 413 views

# Source regions of the type II radio burst observed during a CME–CME interaction on 2013 May 22 by P. Mäkelä et al.*

Occasionally the Sun ejects a pair of magnetized plasma clouds, called coronal mass ejections (CMEs), roughly into the same propagation direction in closely timed sequence. If the second CME is faster than the first one, the CMEs could either just slip through each other or they could collide and interact, [...]... Read more »

• August 16, 2016
• 09:04 AM
• 410 views

# Decameter U-burst Harmonic Pair from a High Loop by Dorovskyy, Melnik, Konovalenko, Bubnov , Gridin, Shevchuk, Rucker, Poedts and Panchenko

We discuss the results of recent observations of a solar U-burst harmonic pair in the frequency range 10-70 MHz, performed by the radio telescope UTR-2 ...... Read more »

Dorovskyy et al. (2016) Decameter U-burst Harmonic Pair from a High Loop by Dorovskyy et al. Solar Physics. info:/

• January 3, 2017
• 07:01 AM
• 382 views

# Observation of quasi-periodic solar radio bursts associated with propagating fast-mode waves by C. R. Goddard et al.*

Flaring activity on the Sun triggers waves and oscillations in the solar corona. The study of these waves and oscillations allows comparisons to magnetohydrodynamic (MHD) theory and modelling to be made, and seismological inversions based on this comparison allow local plasma parameters to be measured indirectly (e.g. De Moortel & [...]... Read more »

• January 17, 2017
• 07:03 AM
• 363 views

# Simultaneous near-Sun observations of a moving type IV radio burst and the associated white-light CME by K. Hariharan et al.*

Quasi-continuum radio emissions of duration ~10-60 min that occur along with flares and coronal mass ejections (CMEs) in the solar atmosphere are termed as type IV bursts. The bursts are non-thermal in nature and can be classified into two categories, i.e. moving type IV (type IVm) bursts and stationary type [...]... Read more »

• February 14, 2017
• 07:02 AM
• 357 views

# Large-scale simulations of Langmuir Wave Distributions Induced by Electron Beams by H. Reid and E. Kontar

Langmuir waves that generate type III radio bursts are excited by high-energy electron beams streaming out from the corona through interplanetary space. Despite a smooth temporal distribution of electrons, the Langmuir waves are measured to occur in discrete clumps, commonly attributed to the turbulent nature of the solar wind electron density (e.g. Smith and Sime 1979, Melrose et al 1986). But how do fluctuations in the background plasma shape the [...]... Read more »

• September 27, 2016
• 09:01 AM
• 356 views

# Diagnostics of the acceleration modulation process based on quasi-periodic variations of flare emission by Kupriyanova et al.*

Quasi-periodic pulsations (QPPs) with the characteristic time scales from a few seconds up to tens of minutes are frequently seen in the time profiles of solar and stellar flare emission (Nakariakov et al., 2016 ). Among all the possibilities of QPPs explanation, two reasons are discussed more actively: magnetohydrodynamic (MHD) [...]... Read more »

Kupriyanova et al. (2016) Diagnostics of the acceleration modulation process based on quasi-periodic variations of flare emission. Solar Physics. info:/