EGU General Assembly 2021
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

3He rich periods measured by the Suprathermal Ion Telescope (SIT) on STEREO-A during solar cycle 24

Marlon Köberle1, Radoslav Bucik2, Nina Dresing3, Bernd Heber1, Andreas Klassen1, and Linghua Wang4
Marlon Köberle et al.
  • 1Institut für Experimentelle und Angewandte Physik, Kiel University, Kiel, Germany (
  • 2Space Science & Engineering Division, Southwest Research Institute, San Antonio, USA
  • 3Department of Physics and Astronomy, University of Turku, Turku, Finland
  • 4Institute of Space Physics and Applied Technology, Peking University, Peking, China

3He-rich solar energetic particle (SEP) events are characterized by a peculiar elemental composition with rare species like 3He or ultra-heavy ions tremendously enhanced over the solar system abundances.
We report on 3He rich SEP periods measured by the Suprathermal Ion Telescope (SIT) onboard STEREO-A beginning in 2007 until 2020, covering the whole solar cycle 24.
The mass resolution capabilities of SIT do not allow to easily distinguish between 3He and 4He especially in cases of a low 3He to 4He ratio.
We therefore developed a semi-automatic detection algorithm to find time periods during which a 3He enhancement can be statistically determined.
Using this method we found 112 3He rich periods.
These periods were further examined in regards of their 3He/4He and Fe/O ratio. 
Previously about ten 3He-rich SEP periods measured by SIT on STEREO-A have been reported.
An association with in-situ electron measurements by STEREO-SEPT and STEREO-STE showed that ~60% of the 112 periods are accompanied with electron events.
The here presented catalogue of 3He rich periods is intended to serve as a reference for the community.

How to cite: Köberle, M., Bucik, R., Dresing, N., Heber, B., Klassen, A., and Wang, L.: 3He rich periods measured by the Suprathermal Ion Telescope (SIT) on STEREO-A during solar cycle 24, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12772,, 2021.

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