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| Titel |
ERNE observations of energetic particles associated with Earth-directed coronal mass ejections in April and May, 1997 |
| VerfasserIn |
A. Anttila, T. Sahla |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 18, no. 11 ; Nr. 18, no. 11, S.1373-1381 |
| Datensatznummer |
250014086
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| Publikation (Nr.) |
 copernicus.org/angeo-18-1373-2000.pdf |
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| Zusammenfassung |
Two Earth-directed coronal mass ejections (CMEs),
which were most effective in energetic (~1–50 MeV) particle acceleration during
the first 18 months since the Solar and Heliospheric Observatory (SOHO) launch,
occurred on April 7 and May 12, 1997. In the analysis of these events we have
deconvoluted the injection spectrum of energetic protons by using the method
described by Anttila et al. In order to apply the method developed
earlier for data of a rotating satellite (Geostationary Operational
Environmental Satellites, GOES), we first had to develop a method to calculate
the omnidirectional energetic particle intensities from the observations of
Energetic and Relativistic Nuclei and Electrons (ERNE), which is an energetic
particle detector onboard the three-axis stabilized SOHO spacecraft. The
omnidirectional intensities are calculated by fitting an exponential pitch angle
distribution from directional information of energetic protons observed by ERNE.
The results of the analysis show that, compared to a much faster and more
intensive CMEs observed during the previous solar maximum, the acceleration
efficiency decreases fast when the shock propagates outward from the Sun. The
particles injected at distances <0.5 AU from the Sun dominate the particle
flux during the whole period, when the shock propagates to the site of the
spacecraft. The main portion of particles injected by the shock during its
propagation further outward from the Sun are trapped around the shock, and are
seen as an intensity increase at the time of the shock passage.
Key words: Interplanetary physics (interplanetary
shocks) – Solar physics, astrophysics and astronomy (energetic particles; flares
and mass ejections) |
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