Structure of the magnetic field in the Ap star HD 187474

Free access article

Issue		A&A Volume 403, Number 1, May III 2003


Page(s)		179 - 185
Section		Stellar atmospheres
DOI		http://dx.doi.org/10.1051/0004-6361:20030322

A&A 403, 179-185 (2003)
DOI: 10.1051/0004-6361:20030322

Structure of the magnetic field in the Ap star HD 187474

V. R. Khalack¹, J. Zverko² and J. Ziznovský²

¹ Main Astronomical Observatory, 27 Zabolotnogo Str., 03680, Kyiv, Ukraine and Isaac Newton Institute of Chile, Kiev Branch
² Astronomical Institute of the SAS, 05960 Tatranská Lomnica, The Slovak Republic

(Received 29 July 2002 / Accepted 21 February 2003 )

Abstract
We reconstruct the complex magnetic field in the Ap star HD 187474 within the frame of the point field source model, where virtual magnetic charges are distributed in the stellar body. The best-fit model describes sufficiently well the observed nonsinusoidal variability of the mean magnetic field modulus and the sinusoidal behaviour of the mean longitudinal magnetic field with the phase of stellar rotation. The best fit provides discrepancy on the level of $\chi^{2}=6.10$ for all the analyzed data. We show that in HD 187474 the magnetic dipole is displaced from centre of the star by 0.055 $R_{\star}$ . The dipole has a size ~0.035 $R_{\star}$ . The angle between the stellar rotational axis and the magnetic dipole is $\beta=37\degr$ .

Key words: stars: chemically peculiar -- stars: magnetic fields -- stars: rotation -- stars: individual: HD 187474

Offprint request: V. R. Khalack, khalack@mao.kiev.ua

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