binaries: spectroscopic; stars: chemically peculiar; stars: early- type; stars: magnetic field; stars: oscillations; stars: individual: HD 96446
Abstract :
[en] <BR /> Aims: HD 96446 is a magnetic B2p He-strong star that has been reported to be a β 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). <BR /> 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. <BR /> 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). Table 3 (RV data) is only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr/">http://cdsarc.u-strasbg.fr</A> (ftp://130.79.128.5) or via <A href="http://cdsarc.u-strasbg.fr/viz- bin/qcat?J/A+A/626/A94">http://cdsarc.u-strasbg.fr/viz- bin/qcat?J/A+A/626/A94</A>
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
González, J. F.; Instituto de Ciencias Astronómicas, de la Tierra y del Espacio (CONICET-Universidad Nacional de San Juan), Casilla de Correo 49, 5400, San Juan, Argentina
Briquet, M.; Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482, Potsdam, Germany ; Space sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, Bât. B5C, 4000, Liège, Belgium
Przybilla, N.; Institut für Astro- und Teilchenphysik, Universität Innsbruck, Technikerstr. 25/8, 6020, Innsbruck, Austria
Nieva, M.-F.; Institut für Astro- und Teilchenphysik, Universität Innsbruck, Technikerstr. 25/8, 6020, Innsbruck, Austria
De Cat, P.; Royal Observatory of Belgium, Ringlaan 3, 1180, Brussels, Belgium
Saesen, S.; Département d'astronomie de l'Université de Genève, Chemin des Maillettes 51, 1290, Versoix, Switzerland
Hubrig, S.; Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482, Potsdam, Germany
Thoul, Anne ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique stellaire théorique et astérosismologie
Pápics, P. I.; Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D, 3001, Leuven, Belgium
Palaversa, L.; Département d'astronomie de l'Université de Genève, Chemin des Maillettes 51, 1290, Versoix, Switzerland ; Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK
Naef, D.; Département d'astronomie de l'Université de Genève, Chemin des Maillettes 51, 1290, Versoix, Switzerland
Neveu-Van Malle, M.; Département d'astronomie de l'Université de Genève, Chemin des Maillettes 51, 1290, Versoix, Switzerland
Järvinen, S.; Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482, Potsdam, Germany
Pollard, K. R.; Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch, New Zealand
Kilmartin, P.; Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch, New Zealand
Mowlavi, N.; Département d'astronomie de l'Université de Genève, Chemin des Maillettes 51, 1290, Versoix, Switzerland
