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

2016-12-20 448 views

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 the primary energy release and electron accelerations in flares (Aschwanden & Benz, 1997, ApJ). A Type-III pair is composed of […]

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

2016-12-13 792 views

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 an ion sound wave \(\mathcal{S}^{\prime}\) through the decay channel \(\mathcal{L} \rightarrow\mathcal{L}^{\prime}+\mathcal{S}^{\prime}\). Usually such wave-wave interactions occur in regions of the […]

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

2016-11-15 770 views

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 through a mechanism called the plasma mechanism. This mechanism attributes the dipole and quadrupole beam patterns for the fundamental and harmonic emissions. […]

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

2016-11-01 807 views

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 surges), chromosphere (UV), transition region (EUV) and corona (X-ray). Jets can occur in different environments such as coronal holes (CHs; Young & […]

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

2016-10-18 914 views

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, and NDA in the frequency range 8-41 MHz. The negative drift rates of these bursts are similar to those of […]

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

2016-08-16 500 views

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 and the recently built first section of the new Giant Ukrainian Radio Telescope (GURT) (see Dorovskyy et al. 2015). A considerably extended frequency range of the new telescope makes the detection of harmonically connected pairs much more probable. In particular, we focus on interpreting the time delay […]

Type III bursts, magnetic field extrapolations, and the propagation of solar energetic particles
by Karl-Ludwig Klein

2008-08-21 407 views

Energetic particle propagation from the Sun to Earth Enhanced fluxes of solar energetic particles (SEP) — so-called SEP events — result from processes of explosive energy conversion in the corona, notably flares and coronal mass ejections. From Parker’s model of the interplanetary magnetic field, it is expected that particles accelerated in the corona reach the Earth, provided they are injected into interplanetary magnetic flux tubes near 50°—60° western longitude. Statistically […]

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