Studying the stellar surface structure and magnetic cycles in very active stars using Doppler imaging and long-term photometric observations

• Applicant: Dr. Heidi Korhonen
• Subject Area: Astrophysics and Astronomy
• Term: from 2003 to 2008
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5417744

Magnetically active stars exhibit, among other phenomena, cool spots on their surface due to magnetically blocked convective flows. In the flip-flop phenomenon, which is seen on some of these stars, the dominant spot region shifts rapidly by 180° in longitude. This behaviour is an example of a type of magnetic activity first observed on stars and then searched for and found on the Sun. The mechanism behind this phenomenon is not known and it may represent a totally new physical process, and as such a new challenge to dynamo theory and the understanding of the Sun. Progress in understanding this phenomenon requires the focused effort of much more elaborate observations than what exists to date. We propose to investigate this phenomenon in detail using: a) time-series of Doppler images obtained with high time resolution of well selected targets b) simultaneous high-precision photometry and c) combining the new photometric data with the existing long-term photometric observations. The aim of this project is to build a detailde picture of the flip-flop in action and correlate the flip-flop phenomenon with other stellar parameters, giving a better basis for interpreting this remarkable phenomenon within the dynamo theory.

• DFG Programme: Research Grants
• Participating Person: Professor Dr. Klaus G. Strassmeier