Poster Abstracts

Name/Affiliation:  Sudeshna Boro Saikia (IAG, University of Goettingen)

Title:  Variablility of the large-scale magnetic field of young sun HN Peg

We investigate the variability of the large-scale magnetic field of the G0 dwarf HN Peg by using spectropolarimetric observations. The large-scale magnetic field topology is reconstructed using Zeeman Doppler Imaging over seven years comprising six observational epochs. The chromospheric variations were also measured using three activity indicators: Ca II H&K, H-alpha and Ca II IRT lines. The magnetic field topology of HN Peg exhibits a variable and complex geometry. The poloidal component exhibits a stable positive polarity magnetic region at each observational epoch. Surprisingly the toroidal component is strongly variable in strength, where a positive polarity toroidal band undergoes significant variations through out the observational timespan. HN Peg exhibits a weak longitudinal magnetic field over the epochs of this analysis, with no significant long term trend. The chromospheric activity indicators exhibit more long-term variations over our time span of observations, where the variability in Ca II H$\&$K and H$\alpha$ proxies exhibit a long-term correlation.