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Zeeman-Doppler imag...
Zeeman-Doppler imaging of five young solar-type stars
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- Willamo, T. (author)
- Univ Helsinki, Dept Phys, POB 64, Helsinki 00014, Finland.
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- Lehtinen, J. J. (author)
- Univ Helsinki, Dept Phys, POB 64, Helsinki 00014, Finland.;Univ Turku, Finnish Ctr Astron ESO FINCA, Vesilinnantie 5, Turku 20014, Finland.
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- Hackman, T. (author)
- Univ Helsinki, Dept Phys, POB 64, Helsinki 00014, Finland.
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- Käpylä, Maarit J. (author)
- Stockholms universitet,Nordiska institutet för teoretisk fysik (Nordita),Aalto University, Finland; Max Planck Institute for Solar System Research, Germany,Aalto Univ, Dept Comp Sci, POB 15400, Aalto 00076, Finland.;Max Planck Inst Solar Syst Res, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.;KTH Royal Inst Technol, NORDITA, Hannes Alfvens Vag 12, S-10691 Stockholm, Sweden.;Stockholm Univ, Hannes Alfvens Vag 12, S-10691 Stockholm, Sweden.
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- Kochukhov, Oleg (author)
- Uppsala universitet,Observationell astrofysik
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- Jeffers, S. V. (author)
- Max Planck Inst Solar Syst Res, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
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- Korhonen, H. (author)
- European Southern Observ ESO, Alonso Cordova 3107, Santiago, Chile.
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- Marsden, S. C. (author)
- Univ Southern Queensland, Ctr Astrophys, Toowoomba, Qld 4350, Australia.
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Univ Helsinki, Dept Phys, POB 64, Helsinki 00014, Finland Univ Helsinki, Dept Phys, POB 64, Helsinki 00014, Finland.;Univ Turku, Finnish Ctr Astron ESO FINCA, Vesilinnantie 5, Turku 20014, Finland. (creator_code:org_t)
- 2022-03-08
- 2022
- English.
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 659
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Abstract
Subject headings
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- Context. The magnetic activity of the Sun changes with the solar cycle. Similar cycles are found in other stars as well, but their details are not known to a similar degree. Characterising stellar magnetic cycles is important for the understanding of the stellar and solar dynamos that are driving the magnetic activity.Aims. We present spectropolarimetric observations of five young, solar-type stars and compare them to previous observations, with the aim to identify and characterise stellar equivalents of the solar cycle.Methods. We use Zeeman-Doppler imaging (ZDI) to map the surface magnetic field and brightness of our targets. The magnetic field is decomposed into spherical harmonic expansions, from which we report the strengths of the axisymmetric versus non-axisymmetric and poloidal versus toroidal components, and we compare them to the Rossby numbers of the stars.Results. We present five new ZDI maps of young, solar-type stars from December 2017. Of special interest is the case of V1358 Ori, which had gone through a polarity reversal between our observations and earlier ones. A less evident polarity reversal might also have occurred in HD 35296. There is a preference for a more axisymmetric field, and possibly a more toroidal field, for the more active stars with lower Rossby number, but a larger sample should be studied to draw any strong conclusions from this. For most of the individual stars, the amounts of toroidal and poloidal field have stayed on levels similar to those in earlier observations.Conclusions. We find evidence for a magnetic polarity reversal having occurred in V1358 Ori. An interesting target for future observations is I1 Ori, which may have a short magnetic cycle of a few years. The correlation between the brightness maps and the magnetic field is mostly poor, which could indicate the presence of small-scale magnetic features of different polarities that cancel one another out and are thus not resolved in our maps.
Subject headings
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
- NATURVETENSKAP -- Fysik -- Fusion, plasma och rymdfysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Fusion, Plasma and Space Physics (hsv//eng)
Keyword
- Stars: activity
- Stars: magnetic field
- Stars: solar-type
- Starspots
- Luminance
- Magnetic fields
- Magnetic polarity
- Solar energy
- Stars
- Axisymmetric
- Doppler imaging
- Magnetic activity
- Solar cycle
- Solar type stars
- Star: activity
- Stars: solar types
- Stellars
- Doppler effect
Publication and Content Type
- ref (subject category)
- art (subject category)
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