Energetic Particle Environment near the Sun from Parker Solar Probe

2020 ◽  
Author(s):  
Nathan Schwadron ◽  
Keyword(s):  
Energetic Particle ◽  
Energetic Particles ◽  
Solar Energetic Particles ◽  
Radiation Environment ◽  
The Sun ◽  
Particle Radiation ◽  
Integrated Science ◽  
Direct Observations ◽  
Interaction Regions ◽  
Inner Heliosphere

<p>NASA’s Parker Solar Probe (PSP) mission recently plunged through the inner heliosphere to perihelia at ~24 million km (~35 solar radii), much closer to the Sun than any prior human made object. Onboard PSP, the Integrated Science Investigation of the Sun (ISʘIS) instrument suite made groundbreaking measurements of solar energetic particles (SEPs). Here we discuss the near-Sun energetic particle radiation environment over PSP’s first two orbits, which reveal where and how energetic particles are energized and transported. We find a great variety of energetic particle events accelerated both locally and remotely. These include co-rotating interaction regions (CIRs), “impulsive” SEP events driven by acceleration near the Sun, and events related to Coronal Mass Ejections (CMEs). These ISʘIS observations made so close to the Sun provide critical information for investigating the near-Sun transport and energization of solar energetic particles that was difficult to resolve from prior observations. We discuss the physics of particle acceleration and transport in the context of various theories and models that have been developed over the past decades. This study marks a major milestone with humanity’s reconnaissance of the near-Sun environment and provides the first direct observations of the energetic particle radiation environment in the region just above the corona.</p>

scholarly journals Ulysses COSPIN observations of cosmic rays and solar energetic particles from the South Pole to the North Pole of the Sun during solar maximum

2003 ◽  
Vol 21 (6) ◽  
pp. 1217-1228 ◽  
Author(s):  
R. B. McKibben ◽  
J. J. Connell ◽  
C. Lopate ◽  
M. Zhang ◽  
J. D. Anglin ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Solar Maximum ◽  
Cosmic Ray ◽  
Energetic Particles ◽  
Solar Energetic Particles ◽  
Polar Regions ◽  
The Sun ◽  
The South ◽  
The North ◽  
Inner Heliosphere

Abstract. In 2000–2001 Ulysses passed from the south to the north polar regions of the Sun in the inner heliosphere, providing a snapshot of the latitudinal structure of cosmic ray modulation and solar energetic particle populations during a period near solar maximum.  Observations from the COSPIN suite of energetic charged particle telescopes show that latitude variations in the cosmic ray intensity in the inner heliosphere are nearly non-existent near solar maximum, whereas small but clear latitude gradients were observed during the similar phase of Ulysses’ orbit near the 1994–95 solar minimum. At proton energies above ~10 MeV and extending up to >70 MeV, the intensities are often dominated by Solar Energetic Particles (SEPs) accelerated near the Sun in association with intense solar flares and large Coronal Mass Ejections (CMEs). At lower energies the particle intensities are almost constantly enhanced above background, most likely as a result of a mix of SEPs and particles accelerated by interplanetary shocks. Simultaneous high-latitude Ulysses and near-Earth observations show that most events that produce large flux increases near Earth also produce flux increases at Ulysses, even at the highest latitudes attained. Particle anisotropies during particle onsets at Ulysses are typically directed outwards from the Sun, suggesting either acceleration extending to high latitudes or efficient cross-field propagation somewhere inside the orbit of Ulysses. Both cosmic ray and SEP observations are consistent with highly efficient transport of energetic charged particles between the equatorial and polar regions and across the mean interplanetary magnetic fields in the inner heliosphere.Key words. Interplanetary physics (cosmic rays) – Solar physics, astrophysics and astronomy (energetic particles; flares and mass ejections)

scholarly journals Properties of Suprathermal-through-Energetic He Ions Associated with Stream Interaction Regions Observed over Parker Solar Probe’s First Two Orb¬¬its

2020 ◽  
Author(s):  
Mihir Desai ◽  
Keyword(s):  
High Speed ◽  
Power Laws ◽  
Low Energy ◽  
Energy Spectra ◽  
The Sun ◽  
Integrated Science ◽  
Time Histories ◽  
Interaction Regions ◽  
Low Energy Ions ◽  
Inner Heliosphere

<p>The Integrated Science Investigation of the Sun (IS☉IS) suite on board NASA’s Parker Solar Probe (PSP) observed six distinct enhancements in the intensities of suprathermal-through-energetic (~0.03-3 MeV nucleon<sup>-1</sup>) He ions associated with corotating or stream interaction regions during its first two orbits. Our results from a survey of the time-histories of the He intensities, spectral slopes, and anisotropies, and the event-averaged energy spectra during these events show: 1) In the two strongest enhancements, seen at 0.35 au and 0.85 au, the higher energy ions arrive and maximize later than those at lower energies. In the event seen at 0.35 au, the He ions arrive when PSP was away from the SIR trailing edge and entered the rarefaction region in the high-speed stream; 2) The He intensities are either isotropic or show sunward anisotropies in the spacecraft frame; and 3) In all events, the energy spectra between ~0.2–1 MeV nucleon<sup>-1</sup>are power-laws of the form ∝E<sup>-2</sup>. In the two strongest events, the energy spectra are well represented by flat power-laws between ~0.03–0.4 MeV nucleon<sup>-1</sup>modulated by exponential roll-overs between ~0.4–3 MeV nucleon<sup>-1</sup>. We conclude that the SIR-associated He ions originate from sources or shocks beyond PSP’s location rather than from acceleration processes occurring atnearby portions of local compression regions. Our results also suggest that rarefaction regions that typically follow the SIRs facilitate easier particle transport throughout the inner heliosphere such that low energy ions do not undergo significant energy loss due to adiabatic deceleration, contrary to predictions of existing models.</p>

Evaluating the Martian radiation environment based on state-of-art measurements and modelling results

2020 ◽  
Author(s):  
Jingnan Guo ◽  
Robert Wimmer-Schweingruber ◽  
Cary Zeitlin ◽  
Donald Hassler ◽  
Bent Ehresmann
Keyword(s):  
Space Exploration ◽  
Galactic Cosmic Rays ◽  
Energetic Particles ◽  
Solar Energetic Particles ◽  
Radiation Environment ◽  
Whole Body ◽  
The Sun ◽  
Deep Space ◽  
Radiation Risks ◽  
Radiation Induced

<p>In recent years, space agencies such as ESA, NASA, the Chinese space agency and even private sectors have been planning human deep space exploration programs to the Moon and Mars. This requires a very timely and thorough investigation to better understand the space weather conditions and effects for such deep space activities in order to further develop mitigation strategies against the associated radiation risks on humans in space.</p> <p>Radiation damage in deep space comes mainly from two sources, Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs). As an omnipresent background, radiation induced by GCRs, which are modulated by solar activities, may increase the chance of long-term health consequences, such as onset of cancer, cardiovascular diseases, skin atrophy, eye cataract, leukemia, anemia, leucopenia and malfunctions of the central nervous system. On the other hand, intense solar energetic particles (SEPs) can be considered as mightily related to deterministic radiation effects which are of great concern for space exploration. Acute radiation syndrome (ARS) or sickness or poisoning or toxicity is induced after a whole-body exposure to high doses of radiation between at the Gy [J/kg] level. Such events, despite of being rather infrequent, could result in severe damage to humans and equipment and lead to potential failure of the entire mission and therefore should be detected and mitigated as immediately as possible.</p> <p>Under different shielding environment, the intensity and composition of the GCRs/SEPs may vary due to the interactions of primary particles (of different energies and charges) with the surrounding material and the generation of secondaries. Therefore, a precise quantification of the change of particle spectra under different shielding environment (e.g., within a spacecraft in deep space or at Martian surface or even subsurface which might be used for future habitat shielding) using a synergistic combination of measurements and particle-transport models is essential for assessing and predicting the radiation environment therein as well as its changes during different solar activities.</p> <p>Another major challenge in predicting the radiation risks for humans in space is the sudden and sporadic radiation induced by SEPs which can be very intense, dynamic and may vary drastically in time and location. Specifically speaking, the radiation and particle enhancement measured at (or predicted for) Earth’s vicinity may be completely different from of that detected elsewhere in the heliosphere as for a Mars mission, due to the different magnetic connection and distance of Mars (or the cruise spacecraft) from the acceleration and release region of SEPs near the Sun. We highlight the utmost importance of utilizing multi-spacecraft in-situ and remote sensing observations of the Sun and the heliosphere to better understand such dynamic events and their dynamic effects across the heliosphere in particular at locations where human explorations may take place.</p>

Characterizing the Dynamics of CME-Driven Coronal Bright Fronts Using The SPREAdFAST Framework 

2021 ◽  
Author(s):  
Mohamed Nedal ◽  
Kamen Kozarev ◽  
Rositsa Miteva
Keyword(s):  
Energetic Particle ◽  
Large Scale ◽  
Numerical Models ◽  
Solar Energetic Particle ◽  
Time Dependent ◽  
Radiation Environment ◽  
Source Surface ◽  
The Sun ◽  
Particle Radiation ◽  
Field Source

<p>In this work, we present a full characterization of over 50 historical Coronal Mass Ejection (CME)-driven compressive waves in the low solar corona, related to solar energetic particle events near Earth, using the Solar Particle Radiation Environment Analysis and Forecasting - Acceleration and Scattering Transport (SPREAdFAST) framework. SPREAdFAST is a physics-based, operational heliospheric solar energetic particle (SEP) forecasting system, which incorporates a chain of data-driven analytic and numerical models for estimating: a) coronal magnetic field from Potential Field Source Surface (PFSS) and Magnetohydrodynamics (MHD); b) dynamics of large-scale coronal (CME-driven) shock waves; c) energetic particle acceleration; d) scatter-based, time-dependent SEP propagation in the heliosphere to specific time-dependent positions. SPREAdFAST allows for producing predictions of SEP fluxes at multiple locations in the inner heliosphere, by modeling their acceleration at CMEs near the Sun, and their subsequent interplanetary transport. We used sequences of base-difference images obtained from the AIA instrument on board the SDO satellite, with 24-second cadence. We calculated time-dependent speeds in both the radial and lateral (parallel to the solar limb) directions, mean intensities and thicknesses of the fronts, and major and minor axes. This is essential for characterizing the SEP spectra near the Sun. The kinematics measurements were used to generate time-dependent 3D geometric models of the wave fronts and time-dependent plasma diagnostics using MHD and DEM model results.</p><p> </p><p> </p>

scholarly journals From the Sun’s south to the north pole – Ulysses COSPIN/LET composition measurements at solar maximum

2003 ◽  
Vol 21 (6) ◽  
pp. 1383-1391 ◽  
Author(s):  
M. Y. Hofer ◽  
R. G. Marsden ◽  
T. R. Sanderson ◽  
C. Tranquille
Keyword(s):  
Energetic Particle ◽  
Solar Physics ◽  
Solar Energetic Particle ◽  
Energetic Particles ◽  
Solar Energetic Particles ◽  
Elemental Abundance ◽  
Interplanetary Shocks ◽  
Activity Maximum ◽  
Interplanetary Physics ◽  
Inner Heliosphere

Abstract. Based on elemental abundance ratios derived from the Ulysses COSPIN/LET measurements, we classified the energetic particle populations during and after the socalled Fast Latitude Scan – the time period during which the Ulysses spacecraft traveled from the highest heliolatitude south to maximum northern latitude, i.e. 27 November 2000 to 13 October 2001 – as being mixed between solar energetic particles (major component) and particles accelerated at stream interaction regions. During the fast latitude scan, the Ulysses spacecraft made the first transit in heliolatitude from pole to pole during solar activity maximum conditions, providing a unique opportunity to acquire energetic particle composition data over a maximum range of heliolatitudes in the inner heliosphere. At low latitudes, based on our elemental abundance analysis, we found that while solar energetic particles dominated, there were indications for particle acceleration at single compression regions in a few instances. In the high heliolatitude range the observed elemental particle compositions are mainly of the solar energetic particle type. Within the statistical errors, the observed abundance ratios were independent of latitude, and were characteristic of solar energetic particles. These observations raise an important question for the theories of particle propagation in the inner heliosphere. The daily elemental abundance ratios of S/O, Mg/O and Si/O shown here are the first measured ratios at high heliolatitudes in the energy range from 13.0 to 30.0 MeV/n.Key words. Interplanetary physics (energetic particles; interplanetary shocks) – Solar physics, astrophysics and astronomy (flares and mass ejections)

scholarly journals Solar energetic particles and their variability from the sun and beyond

2013 ◽  
Author(s):  
R. A. Mewaldt ◽  
C. M. S. Cohen ◽  
G. M. Mason ◽  
T. T. von Rosenvinge ◽  
R. A. Leske ◽  
...  
Keyword(s):  
Energetic Particles ◽  
Solar Energetic Particles ◽  
The Sun

scholarly journals The effects of the big storm events in the first half of 2015 on the radiation belts observed by EPT/PROBA-V

2016 ◽  
Vol 34 (1) ◽  
pp. 75-84 ◽  
Author(s):  
V. Pierrard ◽  
G. Lopez Rosson
Keyword(s):  
Charged Particle ◽  
High Resolution ◽  
Geomagnetic Storm ◽  
Energetic Particle ◽  
High Energy ◽  
Radiation Belts ◽  
Radiation Environment ◽  
Storm Event ◽  
Storm Events ◽  
Particle Radiation

Abstract. With the energetic particle telescope (EPT) performing with direct electron and proton discrimination on board the ESA satellite PROBA-V, we analyze the high-resolution measurements of the charged particle radiation environment at an altitude of 820 km for the year 2015. On 17 March 2015, a big geomagnetic storm event injected unusual fluxes up to low radial distances in the radiation belts. EPT electron measurements show a deep dropout at L > 4 starting during the main phase of the storm, associated to the penetration of high energy fluxes at L < 2 completely filling the slot region. After 10 days, the formation of a new slot around L = 2.8 for electrons of 500–600 keV separates the outer belt from the belt extending at other longitudes than the South Atlantic Anomaly. Two other major events appeared in January and June 2015, again with injections of electrons in the inner belt, contrary to what was observed in 2013 and 2014. These observations open many perspectives to better understand the source and loss mechanisms, and particularly concerning the formation of three belts.

scholarly journals On the Turbulent Reduction of Drifts for Solar Energetic Particles

2021 ◽  
Vol 922 (2) ◽  
pp. 200
Author(s):  
J. P. van den Berg ◽  
N. E. Engelbrecht ◽  
N. Wijsen ◽  
R. D. Strauss
Keyword(s):  
Pitch Angle ◽  
Cosmic Ray ◽  
Energetic Particles ◽  
Solar Energetic Particles ◽  
Particle Distributions ◽  
Magnetic Turbulence ◽  
Field Diffusion ◽  
Background Magnetic Field ◽  
Perpendicular Diffusion ◽  
Inner Heliosphere

Abstract Particle drifts perpendicular to the background magnetic field have been proposed by some authors as an explanation for the very efficient perpendicular transport of solar energetic particles (SEPs). This process, however, competes with perpendicular diffusion caused by magnetic turbulence, which can also disrupt the drift patterns and reduce the magnitude of drift effects. The latter phenomenon is well known in cosmic-ray studies, but not yet considered in SEP models. Additionally, SEP models that do not include drifts, especially for electrons, use turbulent drift reduction as a justification of this omission, without critically evaluating or testing this assumption. This article presents the first theoretical step for a theory of drift suppression in SEP transport. This is done by deriving the turbulence-dependent drift reduction function with a pitch-angle dependence, as is applicable for anisotropic particle distributions, and by investigating to what extent drifts will be reduced in the inner heliosphere for realistic turbulence conditions and different pitch-angle dependencies of the perpendicular diffusion coefficient. The influence of the derived turbulent drift reduction factors on the transport of SEPs are tested, using a state-of-the-art SEP transport code, for several expressions of theoretically derived perpendicular diffusion coefficients. It is found, for realistic turbulence conditions in the inner heliosphere, that cross-field diffusion will have the largest influence on the perpendicular transport of SEPs, as opposed to particle drifts.

First Results from Solar Orbiter’s Energetic Particle Detector

2021 ◽  
Author(s):  
Javier Rodriguez-Pacheco ◽  
Keyword(s):  
Energetic Particle ◽  
Wide Energy Range ◽  
High Temporal Resolution ◽  
The Sun ◽  
Particle Detector ◽  
First Results ◽  
Wide Energy ◽  
Spatio Temporal ◽  
Inner Heliosphere

&lt;p&gt;In this presentation, we will show the first measurements performed by EPD since the end of the commissioning phase until the latest results obtained. During these months EPD has been scanning the inner heliosphere at different heliocentric distances and heliolongitues allowing - together with other spacecraft - to investigate the&amp;#160;spatio-temporal behavior of the particle populations in the inner&amp;#160;heliosphere during solar minimum conditions. Solar Orbiter was launched from Cape Canaveral on February 10th, 2020, thus beginning the journey to its encounter with the Sun. Solar Orbiter carries ten scientific instruments, six remote sensing and four in situ, that will allow the mission main goal: how the Sun creates and controls the heliosphere. Among the in situ instruments, the Energetic Particle Detector (EPD) measures electrons, protons and heavy ions with high temporal resolution over a wide energy range, from suprathermal energies up to several hundreds of MeV/nucleon.&lt;/p&gt;

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