STEREO

The angular and frequency dependence of solar radio burst rise and decay times using multi-spacecraft observations by Nicolina Chrysaphi et al.

2024-08-27

Density fluctuations populating the heliosphere interfere with propagating radio photons, altering their trajectories through frequency-dependent effects like scattering. Crucially, these density fluctuations are anisotropic, leading to anisotropic scattering and directional radio-wave propagation. This means that observers at different positions may obtain different estimations of radio properties. Such effects are particularly evident in solar radio bursts which are emitted through the plasma emission mechanism. It has been shown that detectors at […]

Source positions of an interplanetary type III radio burst and anisotropic radio-wave scattering by X. Chen et al.

2023-12-19

Interplanetary solar radio type III bursts provide the means to remotely study and track energetic electrons propagating in the interplanetary medium. Due to the lack of direct radio source imaging, several methods have been developed to determine the source positions from space-based observations. Moreover, none of the methods consider the propagation effects of anisotropic radio-wave scattering, which would strongly distort the trajectory of radio waves, delay their arrival times, and […]

Anisotropic density turbulence variation from the low corona to 1 au as deduced from solar radio observations by E. Kontar et al.

2023-11-30

Density turbulence in the solar corona and solar wind is evident via the properties of solar radio bursts; angular scattering-broadening of extra-solar radio sources observed through the solar atmosphere, and can be measured in-situ in the solar wind. A viable density turbulence model should simultaneously explain all three types of density fluctuation observations. Solar radio bursts (e.g. Type I, II, III) observed below ~1 GHz are produced predominantly via plasma […]

Separating the effects of earthside and far side solar events by Silja Pohjolainen et al.

2023-11-14

During times of high solar activity flares and coronal mass ejections (CMEs) occur close in time, sometimes even simultaneously, and it may be difficult to identify their source regions. Especially fast CMEs that are observed as propagating fronts high in the corona,  can originate from a region on the Earth-facing side, or from the far side. To determine their origins and direction of propagation, one needs to do a careful […]

Harvest of scientific results by Solar Orbiter Radio and Plasma Waves instrument
by Milan Maksimovic

2022-02-15

For a mission that has just entered its primary science phase, Solar Orbiter has already produced many remarkable results. Released on December 14, 2021, a special issue of Astronomy and Astrophysics brings together a wealth of studies and observations obtained during the mission’s cruise phase. Of the 56 articles published, 25 are based on data from the Radio & Plasma Waves (RPW) instrument (Maksimovic et al., A&A, 2020). The RPW […]

Properties of High-Frequency Type II Radio Bursts and Their Relation to the Associated Coronal Mass Ejections
by A.C. Umuhire et al.*

2021-09-28

Type II radio bursts are slow-drifting and long-lasting radio emission produced by nonthermal electrons accelerated at shocks propagating through the solar corona and interplanetary medium (Nelson & Melrose, 1985). The accelerated electrons generate Langmuir waves, which get converted into electromagnetic radiation by the plasma emission mechanism first identified by Ginzburg & Zhelezniakov (1958). Currently, there is a common understanding that type II radio bursts are produced by shocks formed ahead […]

Non-radial propagation of energetic electrons in solar corona by A. Klassen et al.

2018-10-16

STEREO and near-Earth multi-spacecraft observations of solar energetic particle (SEP) events have revealed that some events show quite unexpected intensity distributions at 1 AU (Dresing et al. 2012, Lario et al. 2013). They can be much broader (circumsolar) (Gómez-Herrero et al. 2015), non-symmetric, and sometimes irregular showing so-called finger distribution (Klassen et al. 2016). It had been suggested that these non-symmetric and irregular distributions, among others, may result from non-radial […]

Long-lasting injection of solar energetic electrons into the heliosphere
by N. Dresing et al.

2018-07-24

The solar energetic particle (SEP) event from 26 Dec 2013 was a so-called widespread event observed by multiple spacecraft. The two STEREO and one close to Earth spacecraft spanned a total longitudinal angle of 210 degrees at that time. Together with the 25 Feb 2014 (Lario et al., 2016, Klassen et al., 2016) this is the widest event ever observed with the STEREO spacecraft. Unusually long-lasting SEP anisotropies together with […]

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