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

2016-08-30 1,041 views

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.*

2016-08-23 753 views

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

2016-08-16 494 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 […]

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

2016-08-09 418 views

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

2016-08-02 387 views

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…

Radio emission and relativistic proton acceleration in the large solar particle event of 20 Jan 2005
by Karl-Ludwig Klein and Sophie Masson

2015-01-16 277 views

Energetic particle acceleration 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. The highest energies of solar energetic nucleons detected in space or through gamma-ray emission in the solar atmosphere are in the GeV range. Where and how the particles are accelerated is still controversial. The most debated candidate processes are […]

Signatures of Magnetoacoustic Wave Trains in Solar Decimetric Radio Type IV Bursts
by Hana Mészárosová, Marian Karlický, Ján Rybák, and Karel Jiricka

2009-11-09 565 views

It has been theoretically predicted (Roberts et al. 1983, 1984) that the periodicity of magnetoacoustic modes can be modified by the time evolution of an impulsively generated signal. One of the obvious sources of such a disturbance is the impulsive flare process. These magnetoacoustic waves are trapped in regions with higher density (e.g., in coronal loops) acting as waveguides. The impulsively generated wave in such a coronal waveguide exhibits three […]

Sixty-five years of solar radioastronomy – review paper published
by Monique Pick and Nicole Vilmer

2009-03-18 165 views

A review paper presenting the input of 65 years of radio observations has been published in the journal Astronomy and Astrophysics Review, October 2008 issue. The authors, Monique Pick and Nicole Vilmer, present first the historical context starting from the early 1940s and then proceed to show how radio astronomy has contributed to our knowledge in solar and solar-terrestrial physics. The review is focused on radio emission from flares and […]

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