Magnetic field topology and chemical spot distributions of the Ap star HD119419

Abstract

Analysis of high-resolution spectropolarimetric observations of early-type magnetic stars is currently the most advanced method of obtaining detailed information on their surface magnetic field topologies and horizontal spot distributions. In this study we analyse a new set of high-quality four Stokes parameter observations of the magnetic Ap star HD119419 - a member of the 14 Myr old Lower Cen-Cru association - for the purpose of studying the surface field topology and mapping the chemical abundance spots. We made use of the circular and linear polarisation data collected for HD119419 with the HARPSpol instrument at the ESO 3.6-m telescope. These observations were analysed with a multi-line magnetic diagnostic technique and modelled in detail with a Magnetic Doppler imaging code. We present a new set of mean longitudinal magnetic field measurements and derive a revised stellar rotational period. We also redetermine the basic stellar atmospheric parameters. Our four Stokes parameter magnetic inversions reveal a moderately complex surface field topology with a mean field strength of 18 kG and a maximum local strength of 24 kG. A poloidal dipolar component dominates the magnetic energy spectrum of the surface field in HD119419. However, significant contributions of the higher-order spherical harmonic components are also present. We show that the dipole plus quadrupole part of the reconstructed field geometry is incapable of reproducing the observed amplitudes and shapes of the Stokes Q and U profiles. The chemical abundance distributions of Fe, Cr, Ti, and Nd, derived self-consistently with the magnetic field geometry, are characterised by large abundance gradients and a lack of clear correlation with the magnetic field structure. This full Stokes vector analysis of HD119419 extends the modern hot-star magnetic mapping investigations to an open cluster Ap star with a well-determined age.

15 pages, 11 figures; accepted for publication in A&A

References in corpus (11)

• The surprising magnetic topology of tauSco: fossil remnant or dynamo output?
• Weak magnetic fields in Ap/Bp stars: Evidence for a dipole field lower limit and a tentative interpretation of the magnetic dichotomy
• Evolutionary state of magnetic chemically peculiar stars
• Magnetic field topology of the unique chemically peculiar star CU Virginis
• Doppler imaging of chemical spots on magnetic Ap/Bp stars. Numerical tests and assessment of systematic errors
• Magnetic field topology and chemical abundance distributions of the young, rapidly rotating chemically peculiar star HR5624
• Three-dimensional magnetic and abundance mapping of the cool Ap star HD 24712 II. Two-dimensional Magnetic Doppler Imaging in all four Stokes parameters
• Magnetic field topology and chemical spot distributions in the extreme Ap star HD 75049
• Effective temperatures of magnetic CP stars from full spectral energy distributions
• The complex magnetic field topology of the cool Ap star 49 Cam
• Stellar model atmospheres with magnetic line blanketing. III. The role of magnetic field inclination

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