Magnetic variability and exoplanet detection thresholds for the young solar analogue V889 Her

Discovering exoplanets orbiting young Suns can provide insight into the formation and earlyevolution of our own solar system, but the extreme magnetic activity of young stars obfuscatesexoplanet detection. This poster presents the results of the long-term monitoring of the magneticfield and chromospheric activity variability of the young solar analogue V889 Her, and evaluatesthe impacts of extreme magnetism on exoplanet detection thresholds. We measured Ca H&Kactivity and reconstructed the large-scale magnetic field for 14 epochs between 2004 and 2019using spectropolarimetric observations taken with the Telescope Bernard Lyot, 3.6-m ESOTelescope and the Anglo-Australian Telescope. Our results show that the large-scale magneticfield of V889 Her may undergo 3-4 yr fluctuations, evolving from weak and simple duringchromospheric activity minima to strong and complex during activity maxima, but without anypolarity reversals. Using Doppler Imaging to filter activity jitter from the stellar radial velocity, weestimate that we could detect Jupiter-mass planets with orbital periods of ~3 d. Theme(s): The Sun and Cool Stars in the Time Domain, Cool Stars as Stellar Systems