Constraining the near-core rotation of the γ Doradus star 43 Cygni using BRITE-Constellation data

Author(s): Konstanze Zwintz, T. Van Reeth, A. Tkachenko, Rainer Kuschnig, Werner Wolfgang Weiss, S. Gössl, Andrzej Pigulski, Gerald Handler, Anthony F J Moffat, A. Popowicz, Gregg A. Wade
Abstract: Context. Photometric time series of the γ Doradus star 43 Cyg obtained with the BRITE-Constellation nano-satellites allow us to study its pulsational properties in detail and to constrain its interior structure.
Aims: We aim to find a g-mode period-spacing pattern that allows us to determine the near-core rotation rate of 43 Cyg and redetermine the star's fundamental atmospheric parameters and chemical composition.
Methods: We conducted a frequency analysis using the 156-day long data set obtained with the BRITE-Toronto satellite and employed a suite of MESA/GYRE models to derive the mode identification, asymptotic period-spacing, and near-core rotation rate. We also used high-resolution spectroscopic data with high signal-to-noise ratio obtained at the 1.2 m Mercator telescope with the HERMES spectrograph to redetermine the fundamental atmospheric parameters and chemical composition of 43 Cyg using the software Spectroscopy Made Easy (SME).
Results: We detected 43 intrinsic pulsation frequencies and identified 18 of them to be part of a period-spacing pattern consisting of prograde dipole modes with an asymptotic period-spacing ΔΠ_l = 1 of 2970_-570⁺⁷⁰⁰ s. The near-core rotation rate was determined to be f_rot = 0.56_-0.14^+0.12 d^-1. The atmosphere of 43 Cyg shows solar chemical composition at an effective temperature, Teff, of 7150 ± 150 K, a log g of 4.2 ± 0.6 dex, and a projected rotational velocity, υsini, of 44 ± 4 km s^-1.
Conclusions: The morphology of the observed period-spacing patterns shows indications of a significant chemical gradient in the stellar interior.
Based on data collected by the BRITE Constellation satellite mission, designed, built, launched, operated and supported by the Austrian Research Promotion Agency (FFG), the University of Vienna, the Technical University of Graz, the Canadian Space Agency (CSA), the University of Toronto Institute for Aerospace Studies (UTIAS), the Foundation for Polish Science & Technology (FNiTP MNiSW), and National Science Centre (NCN).The light curves (in tabular form) are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (http://130.79.128.5) or via cdsarc.u-strasbg.fr/viz-bin/qcat
Organisation(s): Department of Astrophysics
External organisation(s): Leopold-Franzens-Universität Innsbruck, Katholieke Universiteit Leuven, University of California, Santa Barbara, Technische Universität Graz, University of Wrocław, Polish Academy of Sciences (PAS), University of Montreal, Silesian University of Technology, Royal Military College of Canada
Journal: Astronomy & Astrophysics
Volume: 608
No. of pages: 9
ISSN: 0004-6361
DOI: https://doi.org/10.1051/0004-6361/201731784
Publication date: 12-2017
Peer reviewed: Yes
Austrian Fields of Science 2012: 103003 Astronomy, 103004 Astrophysics
Keywords
ASJC Scopus subject areas: Astronomy and Astrophysics, Space and Planetary Science
Portal url: https://ucrisportal.univie.ac.at/en/publications/89bf40e7-d187-4e5e-bf65-b5a5ec8269ae

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