scholarly journals Variable Ion Compositions of Solar Energetic Particle Events in the Inner Heliosphere: A Field Line Braiding Model with Compound Injections

2022 ◽  
Vol 924 (1) ◽  
pp. 22
Author(s):  
Fan Guo ◽  
Lulu Zhao ◽  
Christina M. S. Cohen ◽  
Joe Giacalone ◽  
R. A. Leske ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Energetic Particle ◽  
Radial Distance ◽  
Solar Energetic Particle ◽  
The Sun ◽  
Ion Composition ◽  
Source Regions ◽  
Solar Energetic Particle Events ◽  
Composition Ratios ◽  
Inner Heliosphere

Abstract We propose a model for interpreting highly variable ion composition ratios in solar energetic particle (SEP) events recently observed by the Parker Solar Probe (PSP) at 0.3–0.45 au. We use numerical simulations to calculate SEP propagation in a turbulent interplanetary magnetic field with a Kolmogorov power spectrum from large scales down to the gyration scale of energetic particles. We show that when the source regions of different species are offset by a distance comparable to the size of the source regions, the observed energetic particle composition He/H can be strongly variable over more than two orders of magnitude, even if the source ratio is at the nominal value. Assuming a 3He/4He source ratio of 10% in impulsive 3He-rich events and the same spatial offset of the source regions, the 3He/4He ratio at observation sites also vary considerably. The variability of the ion composition ratios depends on the radial distance, which can be tested by observations made at different radial locations. We discuss the implications of these results on the variability of ion composition of impulsive events and on further PSP and Solar Orbiter observations close to the Sun.

scholarly journals The evolution of inverted magnetic fields through the inner heliosphere

2020 ◽  
Vol 494 (3) ◽  
pp. 3642-3655 ◽  
Author(s):  
Allan R Macneil ◽  
Mathew J Owens ◽  
Robert T Wicks ◽  
Mike Lockwood ◽  
Sarah N Bentley ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Radial Distance ◽  
Occurrence Rate ◽  
Slow Solar Wind ◽  
The Sun ◽  
Radial Evolution ◽  
In Transit ◽  
The Magnetic Field ◽  
Inner Heliosphere

ABSTRACT Local inversions are often observed in the heliospheric magnetic field (HMF), but their origins and evolution are not yet fully understood. Parker Solar Probe has recently observed rapid, Alfvénic, HMF inversions in the inner heliosphere, known as ‘switchbacks’, which have been interpreted as the possible remnants of coronal jets. It has also been suggested that inverted HMF may be produced by near-Sun interchange reconnection; a key process in mechanisms proposed for slow solar wind release. These cases suggest that the source of inverted HMF is near the Sun, and it follows that these inversions would gradually decay and straighten as they propagate out through the heliosphere. Alternatively, HMF inversions could form during solar wind transit, through phenomena such velocity shears, draping over ejecta, or waves and turbulence. Such processes are expected to lead to a qualitatively radial evolution of inverted HMF structures. Using Helios measurements spanning 0.3–1 au, we examine the occurrence rate of inverted HMF, as well as other magnetic field morphologies, as a function of radial distance r, and find that it continually increases. This trend may be explained by inverted HMF observed between 0.3 and 1 au being primarily driven by one or more of the above in-transit processes, rather than created at the Sun. We make suggestions as to the relative importance of these different processes based on the evolution of the magnetic field properties associated with inverted HMF. We also explore alternative explanations outside of our suggested driving processes which may lead to the observed trend.

scholarly journals New Real-Time Model May Protect Astronauts from Space Radiation

Eos ◽  
2019 ◽  
Vol 100 ◽  
Author(s):  
David Shultz
Keyword(s):  
Magnetic Field ◽  
Real Time ◽  
Energetic Particle ◽  
Solar Energetic Particle ◽  
Space Radiation ◽  
Earth’S Magnetic Field ◽  
Time Model ◽  
Solar Energetic Particle Events ◽  
Earth's Magnetic Field

Solar energetic particle events pose an acute risk to space travelers outside the protection of Earth’s magnetic field. A new initiative aims to quantify the danger.

Solar Sources of Impulsive Solar Energetic Particle Events and Their Magnetic Field Connection to the Earth

2006 ◽  
Vol 650 (1) ◽  
pp. 438-450 ◽  
Author(s):  
Nariaki V. Nitta ◽  
Donald V. Reames ◽  
Marc L. DeRosa ◽  
Yang Liu ◽  
Seiji Yashiro ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Energetic Particle ◽  
Solar Energetic Particle ◽  
Solar Energetic Particle Events ◽  
The Earth

Determination of Solar Energetic Particle anisotropies based on four-sector measurements - Study based on STEREO/SEPT in preperation of SolO/EPT

2020 ◽  
Author(s):  
Maximilian Bruedern ◽  
Nina Dresing ◽  
Bernd Heber ◽  
Lars Berger ◽  
Alexander Kollhoff ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Pitch Angle ◽  
Radial Distance ◽  
Solar Energetic Particle ◽  
The Sun ◽  
Angle Scattering ◽  
Bootstrap Approach ◽  
The Magnetic Field ◽  
The Imf

<p>With the launch of Solar Orbiter (SolO) Solar Energetic Particles (SEPs) can be observed at a radial distance of 0.284 to 0.9 AU and an inclination out of the ecliptic up to 34 degree. The properties of SEP observations carry information about their source at the Sun as well as their transport through the interplanetary medium. Their energy is mostly determined close to the Sun. As SEPs propagate outward along the Interplanetary Magnetic Field (IMF) the pitch-angle with respect to the local field is systematically focused due to the radially decreasing IMF. However, stochastic changes are induced by scattering at fluctuations of the IMF. Often the first order anisotropy of SEPs is calculated to disentangle imprints of source and transport. Strong anisotropies indicate periods of weak pitch-angle scattering. Although many modeling and observational studies are based on the anisotropy, its uncertainty is often neglected which could result in inaccurate conclusions. Therefore, we propose a new method based on a bootstrap approach where we consider (1) directional instrument responses, (2) the variation of the magnetic field, and (3) the stochastic nature of detection. Here, we present our procedure and final results for different SEP events using measured data of the IMF and particle fluxes by the Solar Electron and Proton Telescope (SEPT) on board of each STEREO spacecraft. The SEPT provides four viewing directions with a view cone of 0.66 sr each on a three axis stabilized spacecraft. In contrast the Electron and Proton Telescope (EPT) on board SolO also consists of four viewing directions but each telescope has a much smaller view cone of 0.21 sr. Due to the very similar instrument setup we can apply our method both to the SEPT and EPT.</p>

scholarly journals Strength of Coronal Mass Ejection‐driven Shocks near the Sun and Their Importance in Predicting Solar Energetic Particle Events

2007 ◽  
Vol 670 (1) ◽  
pp. 849-856 ◽  
Author(s):  
Chenglong Shen ◽  
Yuming Wang ◽  
Pinzhong Ye ◽  
X. P. Zhao ◽  
Bin Gui ◽  
...  
Keyword(s):  
Coronal Mass Ejection ◽  
Energetic Particle ◽  
Solar Energetic Particle ◽  
The Sun ◽  
Solar Energetic Particle Events ◽  
Mass Ejection

Source Regions of Major Solar Energetic Particle Events

2003 ◽  
Author(s):  
N. V. Nitta ◽  
E. W. Cliver ◽  
A. J. Tylka ◽  
P. Smit
Keyword(s):  
Energetic Particle ◽  
Solar Energetic Particle ◽  
Source Regions ◽  
Solar Energetic Particle Events

scholarly journals Fluxes and fluences of SEP events derived from SOLPENCO

2005 ◽  
Vol 23 (9) ◽  
pp. 3047-3053 ◽  
Author(s):  
A. Aran ◽  
B. Sanahuja ◽  
D. Lario
Keyword(s):  
Energetic Particle ◽  
Radial Distance ◽  
Solar Energetic Particle ◽  
Particle Energy ◽  
Particle Accelerator ◽  
Large Set ◽  
The Sun ◽  
Particle Engineering ◽  
Interplanetary Shocks ◽  
Peak Flux

Abstract. We have developed aran04 a tool for rapid predictions of proton flux and fluence profiles observed during gradual solar energetic particle (SEP) events and upstream of the associated traveling interplanetary shocks. This code, named SOLPENCO (for SOLar Particle ENgineering COde), contains a data base with a large set of interplanetary scenarios under which SEP events develop. These scenarios are basically defined by the solar longitude of the parent solar activity, ranging from E75 to W90, and by the position of the observer, located at 0.4 AU or at 1.0 AU, from the Sun. We are now analyzing the performance and reliability of SOLPENCO. We address here two features of SEP events especially relevant to space weather purposes: the peak flux and the fluence. We analyze how the peak flux and the fluence of the synthetic profiles generated by SOLPENCO vary as a function of the strength of the CME-driven shock, the heliolongitude of the solar parent activity and the particle energy considered. In particular, we comment on the dependence of the fluence on the radial distance of the observer (which does not follow an inverse square law), and we draw conclusions about the influence of the shock as a particle accelerator in terms of its evolving strength and the heliolongitude of the solar site where the SEP event originated.

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