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Features of calcium and strontium distribution on the surface of CP star HD49976 |
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| Authors: | Yu V Glagolevskij A V Shavrina G A Chuntonov D A Lyashko |
| Institution: | 1. Special Astrophysical Observatory, Russian Academy of Sciences, Nizhnii Arkhyz, 369167, Russia 2. Main Astronomical Observatory, National Academy of Sciences, Kiev, 03680, Ukraine 3. Taurida National University, Simferopol, 95007, Ukraine |
| Abstract: | Modelling the magnetic field structure in HD49976, we obtained a map of its magnetic field distribution on the surface and its main parameters. Simulating the distribution of Ca and Sr by the phase dependences of the Ca II 3934 Å and Sr II 4215 Å equivalent line widths revealed that their abundances are most likely increased between the magnetic poles. An insufficiently clear result is due to the structure of the magnetic field of HD49976, which proved to be complex, not corresponding to the central dipole. It is modelled by two dipoles, the stronger of them is in the center of the star, and the other, weaker, is at distance of 0.3R * from the center. The synthetic spectrum method yielded abundances of 28 elements in the moments of magnetic field extrema. The carbon and sulfur abundances proved to be close to the solar values, silicon showed a deficit of 1.0 dex, lithium, calcium, iron and the iron peak elements, strontium, rare earths are in excess, especially significant in the case of rare earths. High-resolution spectropolarimetric observations closely covering the entire rotation period are required to investigate the distribution of chemical elements in complex multi-dipole magnetic configurations, applying the Magnetic Doppler Imaging method. |
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