2006A&A...454..321K

The southern magnetic Bp star HD137509 exhibits complex rotational modulation of the longitudinal field and other magnetic observables. Interpretation of this magnetic variability in the framework of the low-order multipolar field models suggests a very strong quadrupolar component to dominate the surface field topology of HD137509. I have examined the high-quality VLT/UVES spectra of HD137509 and discovered resolved Zeeman split components in some of the spectral lines. The inferred mean surface field modulus, <B≥29kG, agrees with the multipolar model predictions. This confirms the presence of an extremely strong non-dipolar magnetic field in HD137509 and establishes this star as the object with the second-largest field among magnetic chemically peculiar stars.