solar flare – Page 3 – Community of European Solar Radio Astronomers

Predicting Flares and Solar Energetic Particle Events: The FORSPEF Tool
by A. Anastasiadis et al.*

2017-10-10 644 views

A novel operational open-access forecasting system that provides reliable forecasting and nowcasting of solar energetic particle (SEP) events, as well as forecasting of solar flares (SFs) based on precursor information, is presented. FORSPEF offers continuous forecasts and nowcasts of SFs and SEP events, up to 70◦ E/W covering practically the entire course of an active-region (AR) toward the limb (up to ~85◦). The prediction window in the forecasting scheme is […]

Particle acceleration and turbulence during a solar flare
by E.P. Kontar et al.*

2017-06-13 1,810 views

Particle acceleration during solar flares is a highly efficient process, in terms of both the energy (tens of percent of the released magnetic energy can be transferred to the energetic particles) and the particle number (nearly all electrons in the flaring region are accelerated). So-called stochastic acceleration (e.g., Petrosian 2012 for a review) is one of the most popular mechanisms capable of providing these characteristics. In this scenario, the magnetic […]

Multi-Loop Structure of Nonthermal Microwave Sources in a Major Long-Duration Flare
by V. Grechnev et al.*

2017-05-23 602 views

Hard X-ray (HXR) and microwave observations of flares show only a few nonthermal sources. They are simple and compact, especially in impulsive flares, suggesting involvement of one to two loops. Hanaoka (1996) and Nishio et al. (1997) interpreted these observations in terms of double-loop flares. This view was later extended up to long-duration flares (Tzatzakis, Nindos, and Alissandrakis, 2008). A concept of a simple flare loop became dominant. However, observations […]

Quasi-periodic acceleration of electrons in the flare on 2012 July 19
by Jing Huang et al.*

2017-02-28 1,280 views

We study the quasi-periodic pulsations (QPPs) of nonthermal emission in an M7.7 class flare on 2012 July 19 with spatially resolved observations at microwave and HXR bands and with spectral observations at decimetric, metric waves. Microwave emission at 17 GHz of two footpoints, HXR emission at 20–50 keV of the north footpoint and loop top, and type III bursts at 0.7–3 GHz show prominent in-phase oscillations at 270$\,$s. Through the […]

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

2016-12-20 451 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.*

2016-11-29 496 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 1,200 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 1,060 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 […]

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