ESTIMATION OF THE RELEASE TIME OF SOLAR ENERGETIC PARTICLES NEAR THE SUN

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)

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Energetic Particle Environment near the Sun from Parker Solar Probe

10.5194/egusphere-egu2020-6063 ◽

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

NASA&#8217;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 (IS&#664;IS) instrument suite made groundbreaking measurements of solar energetic particles (SEPs). Here we discuss the near-Sun energetic particle radiation environment over PSP&#8217;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), &#8220;impulsive&#8221; SEP events driven by acceleration near the Sun, and events related to Coronal Mass Ejections (CMEs). These IS&#664;IS 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&#8217;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.

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

10.5194/epsc2020-317 ◽

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

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. 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. 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. 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&#8217;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.

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Renewal: New Aspects of Acceleration and Transport of Solar Energetic Particles (SEPs) from the Sun to the Earth

10.21236/ada619635 ◽

2014 ◽

Author(s):

Stephen W. Kahler

Keyword(s):

Energetic Particles ◽

Solar Energetic Particles ◽

The Sun ◽

The Earth

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Occurrence of $^3$He-rich Solar Energetic Particles near Earth and Closer to the Sun

10.22323/1.358.1171 ◽

2019 ◽

Author(s):

M. E. Wiedenbeck ◽

G. M. Mason ◽

C. M. S. Cohen ◽

D. J. McComas ◽

E. R. Christian ◽

...

Keyword(s):

Energetic Particles ◽

Solar Energetic Particles ◽

The Sun

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Solar release time of solar energetic particles and associated acceleration source in corona

Chinese Science Bulletin ◽

10.1007/s11434-008-0030-1 ◽

2008 ◽

Vol 53 (2) ◽

pp. 161-168 ◽

Cited By ~ 2

Author(s):

GuiMing Le ◽

YuHua Tang ◽

YanBen Han

Keyword(s):

Energetic Particles ◽

Solar Energetic Particles ◽

Release Time

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Radio Astronomical Tools for the Study of Solar Energetic Particles I. Correlations and Diagnostics of Impulsive Acceleration and Particle Propagation

Frontiers in Astronomy and Space Sciences ◽

10.3389/fspas.2020.580436 ◽

2021 ◽

Vol 7 ◽

Author(s):

Karl-Ludwig Klein

Keyword(s):

Particle Acceleration ◽

Energetic Particles ◽

Solar Energetic Particles ◽

Relativistic Electrons ◽

The Sun ◽

Radio Bursts ◽

Type Iii ◽

Wide Range ◽

Field Lines ◽

Impulsive Processes

Solar energetic particles (SEPs) are sporadically ejected from the Sun during flares and coronal mass ejections. They are of major astrophysical interest, because the proximity of the Sun allows for detailed multi-messenger studies. They affect space weather due to interactions with electronics, with the Earth’s atmosphere, and with humans if they leave the protective shield of the magnetosphere of the Earth. Since early studies in the 1950s, starting with particle detectors on the ground, SEP events have been related to radio bursts. Two subjects are addressed in this chapter: attempts to establish quantitative correlations between SEPs and microwave bursts produced by gyro synchrotron radiation of mildly relativistic electrons, and the information derived from type III radio bursts on impulsive processes of particle acceleration and the coronal and interplanetary propagation. Type III radio bursts produced by electron beams on open magnetic field lines have a wide range of applications, including the identification of acceleration regions, the identification of confined particle acceleration with coronal signatures, but no SEPs, and the paths that the electrons, and energetic charged particles in general, take to travel from the low corona to the Heliosphere in case they escape. Simple scenarios of coronal particle acceleration are confirmed in relatively simple and short events. But the comparison with particle transport models shows that longer and delayed acceleration episodes exist especially in large SEP events. They will be discussed in a companion chapter.

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Delay in solar energetic particle onsets at high heliographic latitudes

Annales Geophysicae ◽

10.5194/angeo-21-1367-2003 ◽

2003 ◽

Vol 21 (6) ◽

pp. 1367-1375 ◽

Cited By ~ 30

Author(s):

S. Dalla ◽

A. Balogh ◽

S. Krucker ◽

A. Posner ◽

R. Müller-Mellin ◽

...

Keyword(s):

Solar Physics ◽

Solar Energetic Particle ◽

Interplanetary Shock ◽

Energetic Particles ◽

Release Time ◽

The Sun ◽

Interplanetary Physics ◽

Particle Speed ◽

The Difference ◽

Path Lengths

Abstract. Ulysses observations have shown that solar energetic particles (SEPs) can easily reach high heliographic latitudes. To obtain information on the release and propagation of SEPs prior to their arrival at Ulysses, we analyse the onsets of nine large high-latitude particle events. We measure the onset times in several energy channels, and plot them versus inverse particle speed. This allows us to derive an experimental path length and time of release from the solar atmosphere. We repeat the procedure for near-Earth observations by Wind and SOHO. We find that the derived path lengths at Ulysses are 1.06 to 2.45 times the length of a Parker spiral magnetic field line connecting the spacecraft to the Sun. The time of particle release from the Sun is between 100 and 350 min later than the release time derived from in-ecliptic measurements. We find no evidence of correlation between the delay in release and the inverse of the speed of the CME associated with the event, or the inverse of the speed of the corresponding interplanetary shock. The main parameter determining the magnitude of the delay appears to be the difference in latitude between the flare and the footpoint of the spacecraft.Key words. Interplanetary physics (energetic particles) – Solar physics, astrophysics and astronomy (energetic particles, flares and mass ejections)

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