Hostname: page-component-8448b6f56d-dnltx Total loading time: 0 Render date: 2024-04-17T15:53:31.938Z Has data issue: false hasContentIssue false

Stellar nonlinear dynamos: observations and modelling

Published online by Cambridge University Press:  01 November 2008

Ilkka Tuominen
Affiliation:
Observatory, University of Helsinki, PO BOX 14, FI-00014 University of Helsinki, Finland
Maarit J. Korpi
Affiliation:
Observatory, University of Helsinki, PO BOX 14, FI-00014 University of Helsinki, Finland
Petri J. Käpylä
Affiliation:
Observatory, University of Helsinki, PO BOX 14, FI-00014 University of Helsinki, Finland
Marjaana Lindborg
Affiliation:
Observatory, University of Helsinki, PO BOX 14, FI-00014 University of Helsinki, Finland
Ilya Ilyin
Affiliation:
Astrophysical Institute Potsdam, An der Sternwarte 16, D-14482 Potsdam, Germany
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Recent numerical modelling of mean-field stellar dynamos with induction and Reynolds' equations show that, with increasing rotation, field symmetry changes from an axisymmetric solar type to a nonaxymmetric one, where the so-called active longitudes in the same stellar hemisphere are predicted to be of opposite polarities. It was originally named Active star Hale rule in Tuominen et al. (2002), being an analogue to the famous bipolar sunspot polarity rule but different in scale and being a global phenomenon. In addition to long timeseries of temperature mapping and photometry, during the last few years we have been able to measure accurately polarization spectra of an active late-type star II Peg with the upgraded spectropolarimetric option of the high-resolution spectrograph SOFIN at the Nordic Optical Telescope, La Palma. The magnetic inversions (Carroll et al., Kochukhov et al.) can be compared to the dynamo models and the preliminary results show some resemblance to the dynamo solutions.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2009

References

Carroll, T., Kopf, M., Strassmeier, K., Ilyin, I., & Tuominen, I., 2009, this proceedingsGoogle Scholar
Kochukhov, O., Piskunov, N., Ilyin, I., & Tuominen, I., 2009, this proceedingsGoogle Scholar
Käpylä, P.J., Korpi, M.J., Ossendrijver, M., & Stix, M. 2006, A&A 455, 401Google Scholar
Moss, D., Barker, D. M., Brandenburg, A., & Tuominen, I. 1995, A&A 294, 155Google Scholar
Rüdiger, G., Elstner, D., & Ossendrijver, M. 2003, A&A 406, 15Google Scholar
Tuominen, I., Bergyugina, S. V., Korpi, M. J., & Rönty, T. 1999, in Stellar dynamos: Nonlinearity and Chaotic Flows, Nunez, & Ferriz-Mas, (eds.), ASP Conference Series 178Google Scholar
Tuominen, I., Berdyugina, S. V., & Korpi, M. J. 2002, AN 323, 367Google Scholar