Topological changes in the magnetic field of LQ Hya during an activity minimum
| openaire: EC/H2020/818665/EU//UniSDyn Funding Information: Acknowledgements. M.J.K. and J.J.L. acknowledge the Academy of Finland "ReSoLVE". Centre of Excellence (project number 307411) and the Max Planck Research Group 'SOLSTAR' funding. T.H. acknowledges the financial support from the Academy of Finland for the project SOLSTICE (decision no. 324161). T.W. acknowledges financial support from the Alfred Kordelin foundation. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 818665 "UniSDyn"). The automated astronomy program at Tennessee State University has been supported by NASA, NSF, TSU and the State of Tennessee through the Centers of Excellence program. The authors thank Lúcia Duarte for helpful discussions about the model–observation comparisons. Publisher Copyright: © ESO 2022. ; Aims: Previous studies have related surface temperature maps, obtained with the Doppler imaging (DI) technique, of LQ Hya with long-term photometry. Here, we compare surface magnetic field maps, obtained with the Zeeman Doppler imaging (ZDI) technique, with contemporaneous photometry, with the aim of quantifying the star's magnetic cycle characteristics. Methods: We inverted Stokes IV spectropolarimetry, obtained with the HARPSpol and ESPaDOnS instruments, into magnetic field and surface brightness maps using a tomographic inversion code that models high signal-to-noise ratio mean line profiles produced by the least squares deconvolution (LSD) technique. The maps were compared against long-term ground-based photometry acquired with the T3 0.40 m Automatic Photoelectric Telescope (APT) at Fairborn Observatory, which offers a proxy for the spot cycle of the star, as well as with chromospheric Ca ¯II H&K activity derived from the observed spectra. Results: The magnetic field and surface brightness maps reveal similar patterns relative to previous DI and ZDI studies: non-axisymmetric polar magnetic field ...