scholarly journals Spectroscopic EUV observations of impulsive solar energetic particle event sources

2018 ◽  
Vol 617 ◽  
pp. A40 ◽  
Author(s):  
R. Bučík ◽  
A. Fludra ◽  
R. Gómez-Herrero ◽  
D. E. Innes ◽  
B. Kellett ◽  
...  
Keyword(s):  
Energetic Particle ◽  
Extreme Ultraviolet ◽  
Solar Energetic Particle ◽  
Impulsive Phase ◽  
Ion Acceleration ◽  
Solar Energetic Particle Event ◽  
Energetic Ions ◽  
Theoretical Predictions ◽  
Ion Production ◽  
Field Lines

Context. Remote observations of solar flare ion acceleration are rather limited. Theoretical predictions for signatures of ion acceleration in extreme ultraviolet (EUV) line profiles have been made. Previous tests involve observations of flares with no evidence for energetic ions. Aims. We aim to examine a source flare of impulsive (or 3He-rich) solar energetic particle events with EUV line spectroscopy. Methods. We inspected all (more than 90) reported 3He-rich flares of the previous solar cycle 23 and found only 4 (recurrent) jets in the field of view of the Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observatory (SOHO). The jet with the most suitable spatial and temporal coverage was analyzed in detail. Results. Two enhanced (nonthermal) line broadenings are observed in the cooler chromospheric and transition-region lines, and they are localized near the site where the closed magnetic loops reconnect with the open magnetic field lines. The enhanced broadenings are both found at the sites with redshifts in the lines, surrounded by the region with blueshifts. One enhanced line broadening is associated with a small flare without energetic particle signatures, while another occurs just after the particle acceleration signatures of the main flare terminated. Conclusions. The observed excess broadening does not appear to be directly related to the energetic ion production and motions. Further investigations are required that cover the critical impulsive phase of the flare, ideally with high-resolution spectrometers that are specifically pointed to the 3He-rich solar energetic particle source.

scholarly journals Impulsive Solar Energetic Particle Events: Extreme-Ultraviolet Waves and Jets

2022 ◽  
Vol 8 ◽  
Author(s):  
Radoslav Bučík
Keyword(s):  
Energetic Particle ◽  
Large Scale ◽  
Extreme Ultraviolet ◽  
Solar Energetic Particle ◽  
Power Laws ◽  
Heavy Ion ◽  
Energetic Ions ◽  
Solar Energetic Particle Events ◽  
System Composition ◽  
Low Energies

Impulsive solar energetic particle (ISEP) events show peculiar elemental composition, with enhanced 3He and heavy-ion abundances, markedly different from our Solar System composition. Furthermore, the events are characterized by a wide variety of energy spectral shapes from power laws to rounded spectra toward the low energies. Solar sources of the events have been firmly associated with coronal jets. Surprisingly, new observations have shown that events are often accompanied by so-called extreme-ultraviolet (EUV) coronal waves–a large-scale phenomenon compared to jets. This paper outlines the current understanding of the linkage of EUV waves with jets and energetic ions in ISEP events.

scholarly journals The effect of turbulence strength on meandering field lines and Solar Energetic Particle event extents

2018 ◽  
Vol 8 ◽  
pp. A13 ◽  
Author(s):  
Timo Laitinen ◽  
Frederic Effenberger ◽  
Andreas Kopp ◽  
Silvia Dalla
Keyword(s):  
Energetic Particle ◽  
Mean Field ◽  
Early Time ◽  
Solar Energetic Particle ◽  
Field Direction ◽  
Radiation Environment ◽  
Longitudinal Distribution ◽  
Solar Energetic Particle Event ◽  
The Mean ◽  
Field Lines

Insights into the processes of Solar Energetic Particle (SEP) propagation are essential for understanding how solar eruptions affect the radiation environment of near-Earth space. SEP propagation is influenced by turbulent magnetic fields in the solar wind, resulting in stochastic transport of the particles from their acceleration site to Earth. While the conventional approach for SEP modelling focuses mainly on the transport of particles along the mean Parker spiral magnetic field, multi-spacecraft observations suggest that the cross-field propagation shapes the SEP fluxes at Earth strongly. However, adding cross-field transport of SEPs as spatial diffusion has been shown to be insufficient in modelling the SEP events without use of unrealistically large cross-field diffusion coefficients. Recently, Laitinen et al. [ApJL 773 (2013b); A&A 591 (2016)] demonstrated that the early-time propagation of energetic particles across the mean field direction in turbulent fields is not diffusive, with the particles propagating along meandering field lines. This early-time transport mode results in fast access of the particles across the mean field direction, in agreement with the SEP observations. In this work, we study the propagation of SEPs within the new transport paradigm, and demonstrate the significance of turbulence strength on the evolution of the SEP radiation environment near Earth. We calculate the transport parameters consistently using a turbulence transport model, parametrised by the SEP parallel scattering mean free path at 1 AU, λ∥*, and show that the parallel and cross-field transport are connected, with conditions resulting in slow parallel transport corresponding to wider events. We find a scaling σφ,max∝(1/λ∥*)1/4 for the Gaussian fitting of the longitudinal distribution of maximum intensities. The longitudes with highest intensities are shifted towards the west for strong scattering conditions. Our results emphasise the importance of understanding both the SEP transport and the interplanetary turbulence conditions for modelling and predicting the SEP radiation environment at Earth.

Ionospheric and stratospheric electric field responses to an extreme solar energetic particle event

2020 ◽  
Author(s):  
EDGAR Andrew BERING ◽  
Robert H. Holzworth ◽  
Michael McCarthy ◽  
Michael Kokorowski ◽  
Robyn M Millan ◽  
...  
Keyword(s):  
Electric Field ◽  
Energetic Particle ◽  
Solar Energetic Particle ◽  
Solar Energetic Particle Event ◽  
Particle Event

scholarly journals Rapid fluctuations of stratospheric electric field following a solar energetic particle event

2006 ◽  
Vol 33 (20) ◽  
Author(s):  
M. Kokorowski ◽  
J. G. Sample ◽  
R. H. Holzworth ◽  
E. A. Bering ◽  
S. D. Bale ◽  
...  
Keyword(s):  
Electric Field ◽  
Energetic Particle ◽  
Solar Energetic Particle ◽  
Solar Energetic Particle Event ◽  
Particle Event

scholarly journals Parker Solar Probe’s Measurements of the 29 November 2020 Solar Energetic Particle Event

2021 ◽  
Author(s):  
Christina Cohen ◽  
E.R. Christian ◽  
A.C. Cummings ◽  
A.J. Davis ◽  
M.I. Desai ◽  
...  
Keyword(s):  
Energetic Particle ◽  
Solar Energetic Particle ◽  
Solar Energetic Particle Event ◽  
Particle Event

scholarly journals Possible effect of extreme solar energetic particle event of 20 January 2005 on polar stratospheric aerosols: direct observational evidence

2012 ◽  
Vol 12 (2) ◽  
pp. 769-778 ◽  
Author(s):  
I. A. Mironova ◽  
I. G. Usoskin ◽  
G. A. Kovaltsov ◽  
S. V. Petelina
Keyword(s):  
Cosmic Rays ◽  
Energetic Particle ◽  
Middle Atmosphere ◽  
Solar Energetic Particle ◽  
Cosmic Ray ◽  
Observational Evidence ◽  
Temporal Association ◽  
Polar Regions ◽  
Solar Energetic Particle Event ◽  
Stratospheric Aerosols

Abstract. Energetic cosmic rays are the main source of ionization of the low-middle atmosphere, leading to associated changes in atmospheric properties. Via the hypothetical influence of ionization on aerosol growth and facilitated formation of clouds, this may be an important indirect link relating solar variability to climate. This effect is highly debated, however, since the proposed theoretical mechanisms still remain illusive and qualitative, and observational evidence is inconclusive and controversial. Therefore, important questions regarding the existence and magnitude of the effect, and particularly the fraction of aerosol particles that can form and grow, are still open. Here we present empirical evidence of the possible effect caused by cosmic rays upon polar stratospheric aerosols, based on a case study of an extreme solar energetic particle (SEP) event of 20 January 2005. Using aerosol data obtained over polar regions from different satellites with optical instruments that were operating during January 2005, such as the Stratospheric Aerosol and Gas Experiment III (SAGE III), and Optical Spectrograph and Infrared Imaging System (OSIRIS), we found a significant simultaneous change in aerosol properties in both the Southern and Northern Polar regions in temporal association with the SEP event. We speculate that ionization of the atmosphere, which was abnormally high in the lower stratosphere during the extreme SEP event, might have led to formation of new particles and/or growth of preexisting ultrafine particles in the polar stratospheric region. However, a detailed interpretation of the effect is left for subsequent studies. This is the first time high vertical resolution measurements have been used to discuss possible production of stratospheric aerosols under the influence of cosmic ray induced ionization. The observed effect is marginally detectable for the analyzed severe SEP event and can be undetectable for the majority of weak-moderate events. The present interpretation serves as a conservative upper limit of solar energetic particle effect upon polar stratospheric aerosols.

Solar energetic particle event at Mercury

2003 ◽  
Vol 51 (4-5) ◽  
pp. 339-352 ◽  
Author(s):  
F Leblanc ◽  
J.G Luhmann ◽  
R.E Johnson ◽  
M Liu
Keyword(s):  
Energetic Particle ◽  
Solar Energetic Particle ◽  
Solar Energetic Particle Event ◽  
Particle Event
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