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High resolution observations of radio noise storms in the solar corona
by Prasad Subramanian and Claude Mercier

2016-09-06

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. We focus here on radio noise storms, which are very commonplace instances of small electron acceleration episodes. Noise storm sources are relatively small (less than 1 arcmin) and vary over timescales shorter than a second. There can often be […]

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

2016-08-30

The nature of the solar flare sub-THz emission (Kaufmann, 2012) with a positive spectral slope at 200-400 GHz is still not clear [see also previous CESRA highlight]. Some authors associate this emission with thermal bremsstrahlung, while other suggest it is associated with different, non-thermal mechanisms (see Fleishman & Kontar, 2010; Krucker et al., 2013). There are two serious disadvantages of the existing approaches. First, there is a lack of observations in […]

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

2016-08-23

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 frequencies, RHESSI X-rays and SDO/HMI and EUV. It exhibits strikingly good correlation in time and in space with white light […]

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

2016-08-16

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 […]

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

2016-08-09

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<<1) waves and termed particle acceleration by MHD (weak) turbulence. In the other extreme, isolated turbulent shock waves or isolated unstable current sheets (UCS) were studied. The regime […]

Observation of a Quasi-periodic Pulsation in Hard X-Ray, Radio, and Extreme-ultraviolet Wavelengths
by Pankaj Kumar, Valery M. Nakariakov and Kyung-Suk Cho

2016-08-02

Quasi-periodic pulsations (QPPs) with periods from a few seconds to several minutes are often observed during solar/stellar flares in X-ray, radio, and optical wavelength bands. The study of QPPs is useful to understand the physical mechanism for the energy release, plasma heating, and particle acceleration during solar flares…