Ultraviolet (UV)/extreme ultraviolet (EUV) emissions

Energetics of compressive waves in the solar corona by Francesco Azzollini et al

2024-07-02

Inelastic scattering off moving or oscillating density fluctuations leads to broadening of radio signals propagating in the solar corona and solar wind. Using an anisotropic density fluctuation model from the kinetic scattering theory for solar radio bursts, we deduce the plasma velocities (perpendicular to the line of sight) required to explain observations of spacecraft signal frequency broadening. The kinetic energy associated with these inferred bulk velocities cascades to smaller and […]

Searching for optical/EUV counterparts of type IIs in a complex metric burst

by Costas Alissandrakis et al.*

2021-12-07

Solar type II bursts are sporadic emissions characterized by their narrow bandwidth and slow frequency drift in dynamic spectra (Nelson & Melrose, 1985; Vršnak & Cliver 2008; Nindos et al. 2008; Pick & Vilmer 2008). They are attributed to shock waves produced by flare/CME eruptions. However, the association of type IIs with optical or EUV features is not clear; the leading edge or flanks of CMEs, the front of an […]

Localized Microwave and EUV Bright Structures in an Eruptive Prominence
by J. Huang et al.*

2019-07-30

We study a solar eruptive prominence with flare/coronal mass ejection (CME) event by microwave and extreme ultraviolet (EUV) observations. Its evolution can be divided into three phases: slow rise, fast expansion, and ejection. In the slow-rise phase, the prominence continuously twists for more than one hour with a patch of bright emission appearing around the top. When the north leg interacts with the local small-size loops, the fast expansion is […]

Large area solar flare ribbons as the model to explain puzzling millimeter emission
by G.G. Motorina et al.*

2019-03-12

Solar flares are sudden explosive processes, that convert the energy of the magnetic field into the kinetic energy of electrons and ions. Since the beginning of the century, millimeter observations of solar flares became routinely possible at a few frequencies with limited spatial resolution (see Kaufmann 2012, as a review). One of the most puzzling aspects of the observations at millimeter wavelengths (200-400 GHz) is the presence, in some flares, […]

Temperature constraints from inversions of synthetic solar optical, UV and radio spectra
by J. M. da Silva Santos et al*

2019-02-12

While the solar chromosphere has been routinely observed in high-resolution from ground-based optical telescopes such as the Swedish Solar Telescope (SST), and more recently in the UV from space-borne telescopes such as the Interface Region Imaging Spectrograph (IRIS), radio observations lag behind despite their great potential. Distinctly from photospheric lines, most chromospheric diagnostics such as Ca II 854.2 nm and Mg II h and k form under non-LTE conditions, therefore […]

Solar Radio Burst Associated with a Falling Bright EUV Blob
by M. Karlický et al.*

2018-06-12

In several papers the thermal conduction front formed between hot and cold plasmas was studied (Brown et al. 1979, McKean et al 1990, Arber & Melnikov 2009). Karlický (2015) has studied the thermal front using a 3-D particle-in-cell electromagnetic code and found that the thermal front can produce radio emission. Here we present a very rare radio burst which we interpreted as generated by the thermal conduction front formed in […]

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