The corona of the Sun is built up by loops defined through the magnetic field. With high resolution observations made possible by new instruments, coronal structures can be increasingly well resolved. Observations show individual strands with diameters down to a few 100 km, and so far it remains open what defines these strands, in particular their width, and which processes lead to their...
Observations of solar flare reconnection at very high resolution can be indirectly made at the footpoints of reconnected loops into which flare energy is deposited. The response of the lower atmosphere to this energy input includes a downward-propagating shock called chromospheric condensation, which can be observed at wavelengths including UV and visible. In order to characterize...
Particles are accelerated to very high, non-thermal energies during explosive energy-release phenomena in the solar corona and Earth’s magnetotail. While some similarities and differences of the particle acceleration in these environments have been discussed in the literature, it remains unclear exactly how the particle energy spectrum evolves during the energy-release process. Here we show...
A 'proof of principle' is presented, whereby the Ohmic and viscous heating determined by a three-dimensional (3D) MHD model of a coronal avalanche are used as the coronal heating input for field-aligned, one-dimensional (1D) hydrodynamic modelling.
Three-dimensional MHD models cannot afford the computational resources to follow the magnetic field and the thermodynamic transport along field...
Solar flare observations at mid infrared (MID-IR) wavelengths is a relatively new tool that allows to understand the dynamics of flares at chromospheric heights. We present the analysis of a C2.0 class flare, which was observed at the frequency of 30 THz (7.5-13 $\mu$m) with a commercial thermal camera attached to the focus of a Newtonian 20-cm telescope. In order to characterize the temporal...
Solar flares are generally thought to be the impulsive release of magnetic energy giving rise to a wide range of solar phenomena that influence the heliosphere and in some cases even conditions of earth. Part of this liberated energy is used for particle acceleration and to heat up the solar plasma. The Spectrometer/Telescope for Imaging X-rays (STIX) instrument onboard the Solar Orbiter...
Time delays between sub-THz (> 100 GHz) and soft X-ray emission from solar flares with the positive spectral slope at sub-THz frequencies are considered. For 11 solar events we did the cross correlation analysis of light curves obtained with KOSMA (230 GHz), SST (212 GHz), RT-7.5 (93 GHz), and GOES satellites in the 1-8 Å channel in order to detect the Neupert effect. All flares were divided...
Ambient particles passing through reconnecting current sheets gain substantial energy and pitch angle distributions imposed by magnetic field topology. By applying particle-in-cell (PIC) approach in 3D current sheets with single and multiple X and O-nullpoints, or magnetic islands, we explore energy and pitch angle distributions (PADs) of accelerated particles. We show that particles of...
We are planning a new solar satellite mission, "PhoENiX", for understanding of particle acceleration during magnetic reconnection, which are ubiquitous features exhibited by a wide range of plasmas in the universe. The main observation targets of this mission are solar flares, which are generated by magnetic reconnection and accelerate plasma particles. The sun is a unique target in the sense...
A mechanism for the proliferation of large numbers of slow shocks upstream of
reconnecting current layers during impulsive flares is explored. A surprising result of recent macro-scale kinetic simulations of electron energy gain during reconnection was the discovery of the generation of large numbers of slow shocks that extend far upstream of the reconnecting current layer (Arnold et al.,...
Abstract
The radio continuum burst from Sun can be classified into Type I and Type IV. Among Type IV, it can be moving or stationary. The emission process changes as this has a complex radio emission mechanisms. We present the results from the unusual complex type IV bursts. The main component of the radio burst will be a frequently occurring type III burst that is used for flux...
The discovery of large-amplitude narrowband whistler-mode waves at frequencies of tenths of the electron cyclotron frequency in large numbers both at ~1 AU by STEREO S/WAVES and inside ~.3 AU by the Parker Solar Probe Fields Suite provides an answer to longstanding questions about scattering, energization and of solar wind electrons, and regulation of the heat flux. Simultaneous observations...
Particle heating in reconnection is essential to understand the heating in the solar corona, solar flares and the magnetotail. It plays an important role distributing magnetic energy into different species and between thermal and nonthermal components. Previous observational and theoretical studies on electron heating in reconnection exhausts within the beta~1 regime suggest a simple linear...
We conduct detailed thermal analysis of the plasma sheet region during the post-eruption phase of a flare that occurred on September 10, 2017. The plasma sheet that develops is observed using the 131A and 193A filters of the Atmospheric Imaging Assembly (AIA) on the Solar Dynamic Observatory. Intensity data is used to distinguish between loops and the plasma sheet. We utilize the differential...
The outer atmosphere of the Sun, the corona is comprised of tenuous, highly ionized plasma, that is governed by magnetic fields and is heated to more than a million Kelvin. Such hot coronal plasma is thought to be powered by numerous impulsive heating events called nanoflares. What drives these impulsive nanoflares? What role does magnetic field play in coronal heating? We address these...
