The Solar Electron and Proton Telescope for the STEREO Mission

Müller‐Mellin, R.; Böttcher, S.; Falenski, J.; Rode, E.; Duvet, L.; Sanderson, T. R.; Bütler, B.; Johlander, B.; Smit, Hans

doi:10.1007/s11214-007-9204-4

Cited by 134 publications

(98 citation statements)

References 16 publications

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“…Since our main focus is on the acceleration efficiency for electrons, we have analyzed the electron data critically with respect to a potential proton contamination. This effect is described in detail in the paper by Müller-Mellin et al (2008a) and is shown in Fig. 15 of that paper using GEANT 4 simulations.…”

Section: Introductionmentioning

confidence: 86%

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Efficiency of particle acceleration at interplanetary shocks: Statistical study of STEREO observations

Dresing

Theesen

Klassen

et al. 2016

A&A

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Context. Among others, shocks are known to be accelerators of energetic charged particles. However, many questions regarding the acceleration efficiency and the required conditions are not fully understood. In particular, the acceleration of electrons by shocks is often questioned. Aims. In this study we determine the efficiency of interplanetary shocks for <100 keV electrons, and for ions at ∼0.1 and ∼2 MeV energies, as measured by the Solar Electron and Proton Telescope (SEPT) instruments aboard the twin Solar Terrestrial Relations Observatory (STEREO) spacecraft. Methods. We employ an online STEREO in situ shock catalog that lists all shocks observed between 2007 and mid 2014 (observed by STEREO A) and until end of 2013 (observed by STEREO B). In total 475 shocks are listed. To determine the particle acceleration efficiency of these shocks, we analyze the associated intensity increases (shock spikes) during the shock crossings. For the nearrelativistic electrons, we take into account the issue of possible ion contamination in the SEPT instrument. Results. The highest acceleration efficiency is found for low energy ions (0.1 MeV), which show a shock-associated increase at 27% of all shocks. The 2 MeV ions show an associated increase only during 5% of the shock crossings. In the case of the electrons, the shocks are nearly ineffective. Only five shock-associated electron increases were found, which correspond to only 1% of all shock crossings.

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Section: Introductionmentioning

confidence: 86%

“…The second unit is mounted in the north/south direction. The work by Müller-Mellin et al (2008a) clearly shows that protons with energies between 450 and 650 keV contaminate the SEPT electron channels. The same simulations show that, above 400 keV, electrons may also contribute to the ion channels.…”

Section: Instrumentationmentioning

confidence: 99%

Efficiency of particle acceleration at interplanetary shocks: Statistical study of STEREO observations

Dresing

Theesen

Klassen

et al. 2016

A&A

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“…The electron observations used in this work are provided by the Solar Electron and Proton Telescope (SEPT, Müller-Mellin et al 2008) onboard the STEREO spacecraft and the Electron Proton and Alpha Monitor (EPAM) onboard ACE (Gold et al 1998). The SEPT instrument measures electrons in the range of 45-400 keV.…”

Section: Instrumentationmentioning

confidence: 99%

Statistical survey of widely spread out solar electron events observed with STEREO and ACE with special attention to anisotropies

Dresing

Gómez-Herrero

Heber

et al. 2014

A&A

136

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Context. In February 2011, the two STEREO spacecrafts reached a separation of 180 degrees in longitude, offering a complete view of the Sun for the first time ever. When the full Sun surface is visible, source active regions of solar energetic particle (SEP) events can be identified unambiguously. STEREO, in combination with near-Earth observatories such as ACE or SOHO, provides three well separated viewpoints, which build an unprecedented platform from which to investigate the longitudinal variations of SEP events. Aims. We show an ensemble of SEP events that were observed between 2009 and mid-2013 by at least two spacecrafts and show a remarkably wide particle spread in longitude (wide-spread events). The main selection criterion for these events was a longitudinal separation of at least 80 degrees between active region and spacecraft magnetic footpoint for the widest separated spacecraft. We investigate the events statistically in terms of peak intensities, onset delays, and rise times, and determine the spread of the longitudinal events, which is the range filled by SEPs during the events. Energetic electron anisotropies are investigated to distinguish the source and transport mechanisms that lead to the observed wide particle spreads. Methods. According to the anisotropy distributions, we divided the events into three classes depending on different source and transport scenarios. One potential mechanism for wide-spread events is efficient perpendicular transport in the interplanetary medium that competes with another scenario, which is a wide particle spread that occurs close to the Sun. In the latter case, the observations at 1 AU during the early phase of the events are expected to show significant anisotropies because of the wide injection range at the Sun and particle-focusing during the outward propagation, while in the first case only low anisotropies are anticipated. Results. We find events for both of these scenarios in our sample that match the expected observations and even different events that do not agree with the scenarios. We conclude that probably both an extended source region at the Sun and perpendicular transport in the interplanetary medium are involved for most of these wide-spread events.

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“…8.3 are associated with SEP events observed at 1 AU from the Sun, by instruments at L1 or by the twin STEREO spacecraft, or both. Proton and/or electron enhancements are observed with SoHO/ERNE (Torsti et al 1995), STEREO/LET (Mewaldt et al 2008), STEREO/HET (von Rosenvinge et al 2008), STEREO/SEPT (Müller-Mellin et al 2008), and ACE/EPAM (Gold et al 1998) over a wide range of energy (55 keV to 4 MeV for electrons and 1.6 to 130 MeV for protons). Higher energy protons are available from SoHO/EPHIN (penetrating protons at 100-1000 MeV energies) as well as from GOES/HEPAD (only for 9 of the 25 investigated Fermi/LAT events, see Fig.…”

Section: Solar Energetic Particle Events Associated With Fermi/lat Gamentioning

confidence: 99%

X-Ray, Radio and SEP Observations of Relativistic Gamma-Ray Events

Klein¹,

Tziotziou²,

Zucca³

et al. 2017

Astrophysics and Space Science Library

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The rather frequent occurrence, and sometimes long duration, ofray events at photon energies above 100 MeV challenges our understanding of particle acceleration processes at the Sun. The emission is ascribed to pion-decay photons due to protons with energies above 300 MeV. We study the X-ray and radio emissions and the solar energetic particles (SEPs) in space for a set of 25 Fermi -ray events. They are accompanied by strong SEP events, including, in most cases where the parent activity is well-connected, protons above 300 MeV. Signatures of energetic electron acceleration in the corona accompany the impulsive and early post-impulsive -ray emission. -ray emission lasting several hours accompanies in general the decay phase of long-lasting soft X-ray bursts and decametric-tokilometric type II bursts. We discuss the impact of these results on the origin of the -ray events. IntroductionThe advent of the Fermi mission showed that the Sun is an occasional, but unexpectedly frequent, emitter of -ray photons above 100 MeV. These are understood to be produced by pion decays in nuclear interactions involving protons or He-nuclei at energies above 300 MeV/nucleon. One did not expect that the Sun was able to accelerate relativistic protons and nuclei even in seemingly modest flares. These particles are rarely detected in space (<1 event per year). Furthermore, the duration, several hours, of some -ray events is much longer than that of hard X-ray signatures of electron acceleration in the impulsive flare phase.The question of how the -ray emission is related to other signatures of particle acceleration and energy release in the corona is crucial to understanding the origin of the high-energy protons. It might also be expected that such high-energy populations interacting at the Sun are accompanied by particularly energetic solar energetic particle (SEP) events. This chapter is based on 25 events. The Fermi/LAT temporal data were made available to the HESPERIA project by G. Share prior to their publication in a comprehensive paper ). The present chapter introduces the relevant process of emission and pre-Fermi observations of piondecay -rays (Sect. 8.2), and gives an overview of the Fermi/LAT observations (Sect. 8.3). Section 8.3 was prepared by Gerald Share and Ron Murphy. Related X-ray and radio observations and associated SEP events are presented in Sects. 8.4 and 8.5, respectively. Preliminary conclusions on the interpretation of the -ray events are in Sect. 8.6. Theory and Early Observations of Gamma-Ray Emission at Photon Energies >60 MeVOn 1982 Jun 3 the gamma-ray spectrometer on the Solar Maximum Mission satellite observed emission from 0.3 to 100 MeV from a X8.0 GOES-class flare (Forrest et al. 1986). The impulsive flare lasted about 1 min and was followed by a distinct harder emission phase that peaked in about 1 min and lasted for over 15 min. The energy spectrum of this sustained emission displayed a characteristic hump at photon energies above 60 MeV (Fig. 8.1a), which appeared to be consistent with th...

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The Solar Electron and Proton Telescope for the STEREO Mission

Cited by 134 publications

References 16 publications

Efficiency of particle acceleration at interplanetary shocks: Statistical study of STEREO observations

Efficiency of particle acceleration at interplanetary shocks: Statistical study of STEREO observations

Statistical survey of widely spread out solar electron events observed with STEREO and ACE with special attention to anisotropies

X-Ray, Radio and SEP Observations of Relativistic Gamma-Ray Events

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