Naslov
HD 96446: a long-period binary with a strongly magnetic He-rich primary with β Cephei pulsations

Autori
González, J. F. ; Briquet, M. ; Przybilla, N. ; Nieva, M.-F. ; De Cat, P. ; Saesen, S. ; Hubrig, S. ; Thoul, A. ; Pápics, P. I. ; Palaversa, L. ; Naef, D. ; Neveu-Van Malle, M. ; Järvinen, S. ; Pollard, K. R. ; Kilmartin, P. ; Mowlavi, N. ; Butler, K.

Izvornik
Astronomy & Astrophysics (0004-6361) 626 (2019); A94, 15

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
binaries: spectroscopic ; stars: chemically peculiar ; stars: early-type ; stars: magnetic field ; stars: oscillations ; stars: individual: HD 96446

Sažetak
Aims. HD 96446 is a magnetic B2p He-strong star that has been reported to be beta Cep 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 similar to 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).

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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