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Space storms: Solar and stellar variability, seasonal pattern predictability and societal consequences

Consortium project funded by the Academy of Finland 2020-3, decision No. 324161.

Consortium PI: Eija Tanskanen, Sodankylä observatory

Co-PI: Thomas Hackman, Department of Physics, University of Helsinki

Description of project: The goal of the project is to examine space storms and the magnetic disturbances caused by them. Ground magnetic data will be used from 1844 onwards and thus the changes in the near-Earth magnetic environment can be studied for over 16 solar cycles. One of the goals is to find out how the Sun has varied in different time-scales and how the variability has affected to the near-Earth magnetic climate in different latitudes, and how strong space storms the Sun is capable of producing. We will investigate the predictability of the auroral substorms and other geomagnetic disturbances based on the solar and solar wind data, separately in auroral zone, sub-oval and polar cap. Stellar measurements will be used for examining the link between active regions and super-flares and estimate the occurrence rates for extreme events.

University of Helsinki stellar astrophysics research group

The University of Helsinki research group focuses on observations of stellar magnetic activity. The goal is to use these observations for a better general understanding of the magnetic activity of solar type stars, and in particular the Sun's activity. We also investigate the influence of a stars activity on the detectability of exoplanets. We use the following observations:

  • High resolution spectroscopy from e.g. the Nordic Optical Telescope (NOT) and telescopes of the European Southern Observatory (ESO)
  • Spectropolarimetry from e.g. the NOT and ESO
  • Ground based photometry from e.g. Automated Photometric Telescopes
  • Space based high precision photometry from e.g. the Transiting Exoplanet Survey Satellite
  • Ground-based Ca II H&K monitoring surveys
  • Radiocarbon measurements from tree rings

Methods we are using include Doppler imaging, Zeeman-Doppler imaging (ZDI) and time series analysis. Radiocarbon measurements are used to detect historical solar energetic particle events.

Fig. 1. ZDI images of the young solar-type star LQ Hya taken at the epochs  January 2010, February 2011, January 2016, and December 2017. The images show that a polarity reversal occurred in 2016-7 (Lehtinen et al. 2022).

The research team consists of:

  • Thomas Hackman, PhD, University researcher
  • András Haras-Kiss, MSc, Doctoral student
  • Jyri Lehtinen, PhD, post-doc researcher (Finnish Centre for Astronomy with ESO)
  • Nora Routamo, BSc, master student
  • Mikko Tuomi, PhD, University researcher
  • Teemu Willamo, PhD
  • Joonas Uusitalo, MSc, doctoral student (Laboratory of Chronology, University of Helsinki)

Recent presentations at seminars and scientific conferences

Posters at the  21st Cambridge Workshop: Cool Stars, Stellar Systems and the Sun in Toulouse 4-9 July: 

Recent publications by team members

Lehtinen, J.J., Käpylä, M.J., Hackman, T., Kochukhov, O., Willamo, T., Marsden, S.C., Jeffers, S.V., Henry, G.W., Jetsu, L., 2022, ”Topological changes in the magnetic field of LQ Hya during an activity minimum”, A&A 660, A141

Uusitalo, J, Arppe L., Helamaa, S. et al., 2022, "From lakes to ratios: 14C measurement process of the Finnish tree-ring research consortium", NIMPB 519, 37

Willamo, T., 2022, "Stellar activity : starspots, magnetic fields and activity cycles", PhD thesis, University of Helsinki, Report series in Astronomy 30

Willamo, T., Hackman, T., Lehtinen, J.J., Korpi-Lagg, M., Kochukhov, Oleg, 2022, ”V889 Her: abrupt changes in the magnetic field or differential rotation?”, OJAp 5, 10

Willamo, T., Lehtinen, J.J., Hackman, T., Käpylä, M. J., Kochukhov, O., Jeffers, S.V., Korhonen, H., Marsden, S.C, 2022, ”Zeeman-Doppler imaging of five young solar-type stars”, A&A 659, A71

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