---
abstract: 'The energetic particle instrument ERNE on-board SOHO started its observations
  on December 15, 1995. The low-energy sensor of ERNE, LED, is capable of measuring
  particles in the energy range from 1 to 10 MeV nucl$^-1$. From the beginning of
  the year 1996 until May 22, 1996, LED-observations included four energetic particle
  events above threshold intensities. An energetic particle event caused by a corotating
  interaction region that accelerated protons upto \ensuremath\backsim 10 MeV,
  was observed during January 20-25. Another similar particle event occured on May
  6-12. The events were separated by four solar rotation periods. They had similar
  time profiles, but the one in May had a harder spectrum and a lower intensity level.
  The $^4$He-to-proton ratios were in accordance with the solar wind value. Energetic
  particles observed during April 22-23 and May 14-17 were accelerated at the Sun.
  The first one was apparently an outcome from an active region observed on the west
  limb by telescopes on-board SOHO. Protons were detected at energies from 1 to \ensuremath\backsim10
  MeV. For this event, the$^4$He-to-proton ratio in the range 1.5-5 MeV nucl$^-1$
  was \ensuremath\backsim 3\%. No $^3$He ions were detected. The period of May
  14-15 was, in contrast, extremely $^3$He-rich: it had a$^3$He-to-proton ratio
  of 1.5 \ensuremath\pm 0.6 and a $^3$He-to- $^4He$ ratio as high as \ensuremath\backsim
  8. The period of May 14-17 comprised at least three individual, one-day-long events.
  The first two events were $^3$He-rich, while the last one seemed to have a normal
  composition.'
adsnote: Provided by the SAO/NASA Astrophysics Data System
adsurl: https://ui.adsabs.harvard.edu/abs/1997SoPh..170..179T
authors:
- J. Torsti
- E. Valtonen
- L. G. Kocharov
- R. Vainio
- E. Riihonen
- A. Anttila
- T. Laitinen
- M. Teittinen
- J. Kuusela
category: publications
date: '1997-01-01'
doi: 10.1023/A:1004963118224
draft: false
featured: false
journal: Sol. Phys.
month: January
number: '1'
pages: 179-191
projects: []
publication: Sol. Phys.
publication_types:
- '2'
tags:
- Solar wind
- Interaction region
- Energetic particle
- Normal composition
- Rotation period
title: 'First Energetic Particle Events Observed by the ERNE Instrument'
type: ARTICLE
volume: '170'
year: '1997'
---