Magnetic Field Variations with a Rotational Period on Solar‐like Star ξ Bootis A

Abstract

We examine the global configuration of the magnetic field of the active dwarf ξ Boo A as a function of stellar rotation phase (P = 6.1455 ± 0.0003 days), using direct high-precision spectropolarimetric measurements. The magnetic field varies from -10 G up to +30 G. Integrated magnetic flux on the surface changes polarity during a single rotation period on ξ Boo A, resulting in a flux ratio of ΔΦ+/ΔΦ- ~ 1.5. This is the first study of the general magnetic field as a function of rotation on a solar-like star other than the Sun.