Magnetic field and chromospheric activity evolution of HD75332: a rapid magnetic cycle in an F star without a hot Jupiter

Studying cool star magnetic activity gives an important insight into the stellar dynamo and its relationship with stellar properties, as well as allowing us to place the Sun's magnetism in the context of other stars. Only 61 Cyg A (K5V) and tau Boo (F8V) are currently known to have magnetic cycles like the Sun's, where the large-scale magnetic field polarity reverses in phase with the star's chromospheric activity cycles. tau Boo has a rapid similar to 240d magnetic cycle, and it is not yet clear whether this is related to the star's thin convection zone or if the dynamo is accelerated by interactions between tau Boo and its hot Jupiter. To shed light on this, we studied the magnetic activity of HD75332 (F7V) which has similar physical properties to tau Boo and does not appear to host a hot Jupiter. We characterized its long-term chromospheric activity variability over 53yr and used Zeeman Doppler Imaging to reconstruct the large-scale surface magnetic field for 12 epochs between 2007 and 2019. Although we observe only one reversal of the large-scale magnetic dipole, our results suggest that HD75332 has a rapid similar to 1.06yr solar-like magnetic cycle where the magnetic field evolves in phase with its chromospheric activity. If a solar-like cycle is present, reversals of the large-scale radial field polarity are expected to occur at around activity cycle maxima. This would be similar to the rapid magnetic cycle observed for tau Boo, suggesting that rapid magnetic cycles may be intrinsic to late-F stars and related to their shallow convection zones.

Automated summary

Studying cool star magnetic activity provides insights into the stellar dynamo and its connection with stellar properties, helping us understand the Sun's magnetism in relation to other stars. Research on HD75332 suggests the presence of a rapid solar-like magnetic cycle, possibly linked to its formation mechanisms.