Stellar modelling of Spica, a high-mass spectroscopic binary with a β Cep variable primary component

Autor(en): A. Tkachenko, Jaymie M. Matthews, Conny Aerts, K. Pavlovski, Peter Papics, Rainer Kuschnig, Werner Wolfgang Weiss, Konstanze Zwintz, Chris Cameron, Gordon A. H. Walker, Pieter Degroote, J. Debosscher, Ehsan Moravveji, V. Kolbas, David B. Guenther, Anthony F J Moffat, Jason F. Rowe, Slavek M. Rucinski, Dimitar Sasselov
Abstrakt: Binary stars provide a valuable test of stellar structure and evolution, because the masses of the individual stellar components can be derived with high accuracy and in a model-independent way. In this work, we study Spica, an eccentric double-lined spectroscopic binary system with a β Cep type variable primary component. We use state-of-the-art modelling tools to determine accurate orbital elements of the binary system and atmospheric parameters of both stellar components. We interpret the short-period variability intrinsic to the primary component, detected on top of the orbital motion both in the photometric and spectroscopic data. The non-local thermodynamic equilibrium based spectrum analysis reveals two stars of similar atmospheric chemical composition consistent with the present-day cosmic abundance standard. The masses and radii of the stars are found to be 11.43 ± 1.15 M_⊙ and 7.21 ± 0.75 M_⊙, and 7.47 ± 0.54 R_⊙ and 3.74 ± 0.53 R_⊙ for the primary and secondary, respectively. We find the primary component to pulsate in three independent modes, of which one is identified as a radial mode, while the two others are found to be non-radial, low degree l modes. The frequency of one of these modes is an exact multiple of the orbital frequency, and the l = m = 2 mode identification suggests a tidal nature for this particular mode. We find a very good agreement between the derived dynamical and evolutionary masses for the Spica system to within the observational errors of the measured masses. The age of the system is estimated to be 12.5 ± 1 Myr.
Organisation(en): Institut für Astrophysik
Externe Organisation(en): Katholieke Universiteit Leuven, University of Zagreb, Leopold-Franzens-Universität Innsbruck, Cape Breton University, NASA Ames Research Center, University of British Columbia (UBC), Saint Mary's University, Université de Montréal, University of Toronto, Harvard-Smithsonian Center for Astrophysics
Journal: Monthly Notices of the Royal Astronomical Society
Band: 458
Seiten: 1964-1976
Anzahl der Seiten: 13
ISSN: 0035-8711
DOI: https://doi.org/10.1093/mnras/stw255
Publikationsdatum: 05-2016
Peer-reviewed: Ja
ÖFOS 2012: 103003 Astronomie, 103004 Astrophysik
Schlagwörter
ASJC Scopus Sachgebiete: Astronomy and Astrophysics, Space and Planetary Science
Link zum Portal: https://ucrisportal.univie.ac.at/de/publications/stellar-modelling-of-spica-a-highmass-spectroscopic-binary-with-a--cep-variable-primary-component(6fe9c2c2-db6c-4912-832b-496883de859e).html

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