Constraining the near-core rotation of the γ Doradus star 43 Cygni using BRITE-Constellation data
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 ΔΠl = 1 of 2970-570+700 s. The near-core rotation rate was determined to be frot = 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.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- December 2017
- DOI:
- 10.1051/0004-6361/201731784
- arXiv:
- arXiv:1710.02364
- Bibcode:
- 2017A&A...608A.103Z
- Keywords:
-
- asteroseismology;
- stars: individual: 43 Cygni;
- stars: interiors;
- stars: oscillations;
- stars: fundamental parameters;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 9 pages, 8 figures, accepted by A&