Composite model for the magnetic field of HD 21699 |
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Authors: | Yu V Glagolevskij G A Chuntonov |
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Institution: | (1) Special Astrophysical Observatory, Russian Academy of Sciences, Russia |
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Abstract: | A model is constructed for the magnetic field of the He-weak CP star HD 21699. This star has the field structure of a dipole
displaced by 0.4 radii from the center perpendicular to its axis. The magnetic poles appear to be close to one another on
the surface; they are separated by 55°, not by 180° as in the case of a central dipole. The phase dependences of the equivalent
widths of He and Si lines have extrema at the phases corresponding to passage through the visible meridian of zero magnetic
field between the magnetic poles. At the magnetic poles, the intensity of the helium lines is maximal and of the silicon lines,
minimal. The silicon abundance is maximal in the regions where the magnetic field is predominantly tangential to the star’s
surface. Because of averaging over the visible hemisphere and owing to the closeness of the magnetic poles, only one wave
of variation in the intensity of the spectral lines of these chemical elements, one wave of photometric variability, and an
average surface magnetic field Bs are observed.
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Translated from Astrofizika, Vol. 50, No. 3, pp. 441–451 (August 2007). |
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Keywords: | stars magnetic field chemical abundance |
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