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标题：HD 96446: a long-period binary with a strongly magnetic He-rich primary with β Cephei pulsations ⋆
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作者：J. F. González ; M. Briquet ; N. Przybilla 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2019
卷号：626
DOI：10.1051/0004-6361/201935177
语种：English
出版社：EDP Sciences
摘要：Aims. HD 96446 is a magnetic B2p He-strong star that has been reported to be aβCep pulsator. We present a detailed spectroscopic analysis of this object based on an intensive observational data set obtained in a multisite campaign with the spectrographs CORALIE, FEROS, and HARPS (La Silla); UVES (Paranal); HERCULES (Mt. John Observatory); and GIRAFFE (SAAO).Methods. Radial velocities were measured by cross-correlations and analysed to detect periodic variations. On the other hand, the mean spectrum was fit with spectral synthesis to derive atmospheric parameters and chemical abundances.Results. From the analysis of radial velocities, HD 96446 was found to be a spectroscopic binary with a period of 799 days. The stellar companion, which contributes only ∼5% of the total flux, is an A0-type star. A frequency analysis of the radial velocities allowed us to detect two pulsational modes with periods 2.23 h and 2.66 h. The main mode is most probably a low-inclination, dipole mode (l, m) = (1, 0), and the second pulsation mode corresponds to (l, m) = (2, 2) or to a pole-on (l, m) = (3, 2) configuration. In addition to radial velocities, the main pulsation mode is evidenced through small variations in the spectral morphology (temperature variations) and the light flux. The rotation period of 23.4 d, was detected through the variation in line intensities. Chemical abundances are unevenly distributed over the stellar surface, with helium concentrated at the negative magnetic pole and most metals strengthened at lower latitudes. The mean chemical abundance of helium is strongly abnormal, reaching a value of 0.60 (number fraction).
关键词：enbinaries: spectroscopicstars: chemically peculiarstars: early-typestars: magnetic fieldstars: oscillationsstars: individual: HD 96446