  As part of the Bcool project, over 150 solar-type stars chosen mainly from
planet search databases have been observed between 2006 and 2013 using the
NARVAL and ESPaDOnS spectropolarimeters on the Telescope Bernard Lyot (Pic du
Midi, France) and the Canada France Hawaii Telescope (Mauna Kea, USA),
respectively. These single 'snapshot' observations have been used to detect the
presence of magnetic fields on 40% of our sample, with the highest detection
rates occurring for the youngest stars. From our observations we have
determined the mean surface longitudinal field (or an upper limit for stars
without detections) and the chromospheric surface fluxes, and find that the
upper envelope of the absolute value of the mean surface longitudinal field is
directly correlated to the chromospheric emission from the star and increases
with rotation rate and decreases with age.
