Evolution of global stellar magnetic fields in A and B stars
John D. Landstreet, Stefano Bagnulo, Gregg A. Wade

Abstract: The evolution of magnetic fields through the main sequence lifetimes, of magnetic A and B stars is still very poorly constrained from, observations, largely because of the difficulty of determining, accurate ages for such stars. Using the new generation of powerful, stellar spectropolarimeters, especially FORS1 at ESO and ESPaDOnS at, the CFHT, it is now possible to study this evolution empirically in, open cluster stars, for which relatively accurate ages are available,, and thus for the first time to obtain a sample of magnetic stars with, well determined evolutionary ages. This project has now provided the, first indications of how the fields in these stars change with, age. Our ongoing survey also makes possible some direct comparisons of, achievable field strength uncertainties between FORS1 and ESPaDOnS.