MPS Seminar: The magnetic cycle andplanetary environment of the young Sun Iota Horologii (J. Alvarado Gómez)

Analogous to the 11-yearSolar activity cycle, a large fraction of late-type stars (~60%) showchromospheric activity cycles, with periods ranging from 2.5 to 25 years. For avery limited number of these systems the coronal X-ray counterparts of theseactivity cycles have been also identified. Iota Horologii stands out from thissample, with the shortest chromospheric and coronal activity cycle known todate (1.6 yr). Furthermore, an age estimate of ~ 600 Myr, commensurable withthe time when life started on Earth (~ 4.1 Gyr ago), and a planetary companionlocated at roughly 1 AU, make iota Horologii a truly remarkable object. The initialresults from an HARPSpol@ESO3.6mobservational campaign devoted to map the magnetic cycle of iota Horologii,will be presented. Using the technique of Zeeman-Doppler Imaging (ZDI),magnetic field maps at different epochs are being recovered. This providesdetailed information about the large-scale field evolution and the cyclicactivity phenomena, essential parameters for any physical mechanism proposed inthe magnetic field generation (e.g. dynamo theories). In addition, therecovered surface magnetic field maps serve as input to self-consistently modelthe coronal structure, wind and astrospheric conditions around the star. Thisallow us to study in detail the impact due to the stellar magnetic field andassociated phenomena, on the planetary conditions (e.g. habitability) andevolution, generating in this way strong synergies with other scientific areassuch as Planetary Sciences and Astrobiology.