  The large-scale magnetic field of solar-type stars reconstructed from their
spectropolarimetric observations provide important insight into their
underlying dynamo processes.We aim to investigate the temporal variability of
the large-scale surface magnetic field and chromospheric activity of a young
solar analogue, the G0 dwarf HN Peg.The large-scale surface magnetic field
topology is reconstructed using Zeeman Doppler Imaging at six observational
epochs covering seven years.We also investigated the chromospheric activity
variations by measuring the flux in the line cores of the three chromospheric
activity indicators: Ca II H&K, H alpha, and the Ca II IRT lines.The magnetic
topology of HN Peg shows a complex and variable geometry. While the radial
field exhibits a stable positive polarity magnetic region at the poles at each
observational epoch, the azimuthal field is strongly variable in strength,
where a strong band of positive polarity magnetic field is present at
equatorial latitudes. This field disappears during the middle of our time span,
reappearing again during the last two epochs of observations. The mean magnetic
field derived from the magnetic maps also follow a similar trend to the
toroidal field, with the field strength at a minimum in epoch 2009.54. Summing
the line of sight magnetic field over the visible surface at each observation,
HN Peg exhibits a weak longitudinal magnetic field ranging from -14 G to 13 G,
with no significant long-term trend, although there is significant rotational
variability within each epoch. Those chromospheric activity indicators exhibit
more long-term variations over the time span of observations, where the minimal
is observed in Epoch 2008.71.
