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

2016-12-20 444 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 […]

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

2016-11-29 491 views

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 a solar flare in bremsstrahlung hard X-rays and synchrotron+free-free submillimeter emission. For this we chose a particular event that presents […]

Energetic electrons generated during solar flares
by Gottfried Mann

2016-11-22 1,167 views

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, the Sun is a giant particle accelerator. Basically, a flare occurs as a local enhancement of the Sun’s emission of […]

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

2016-08-30 1,038 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.*

2016-08-23 751 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 […]

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

2015-01-16 276 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 […]

Are there Radio-quiet Solar Flares?
by Arnold Benz

2007-01-04 95 views

Solar flares accelerate particles, and their distribution is usually non-thermal. Non-thermal electrons are prone to velocity space instabilities driving various plasma waves which, in turn, couple into observable radio waves. Such coherent emissions are the result of the combined action of many electrons organized by kinetic plasma waves and can therefore be extremely efficient. Small coherent radio bursts at the limit of present routine observations emit an energy of some […]

Particle acceleration during flares – the part played by an outflow termination shock
by Gottfried Mann

2006-10-11 68 views

During solar flares energetic nonthermal electromagnetic radiation up to the gamma-ray range is emitted from the solar atmosphere, implying the generation of accelerated electrons and ions. Particle acceleration in cosmic plasma is of fundamental physical interest. The solar corona offers detailed remote sounding of these processes. A fine example An interesting example is the X17-flare of 28 October 2003, one of the strongest events of the last activity cycle. Figure 1 […]

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