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

TL;DR

This study uses BRITE-Constellation data and spectroscopic analysis to investigate the pulsational properties, internal rotation, and atmospheric parameters of the gamma Doradus star 43 Cygni, revealing its near-core rotation and internal structure.

Contribution

It provides the first detailed period spacing pattern and near-core rotation rate for 43 Cygni, combining space-based photometry with spectroscopic data for comprehensive stellar modeling.

Findings

Detected 43 pulsation frequencies, identified 18 in a period spacing pattern.

Determined near-core rotation rate of 0.56 d^{-1}.

Found solar chemical composition and specific atmospheric parameters.

Abstract

Photometric time series of the $\gamma$ Dor 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. 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. We conducted a frequency analysis using the 156-days 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, high signal-to-noise ratio spectroscopic data obtained at the 1.2m 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). 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 $\Delta \Pi_{l=1}$ of $2970^{+700}_{-570} \rm s$. The near-core rotation rate was determined to be $f_{\rm rot} = 0.56^{+0.12}_{-0.14}\,\rm d^{-1}$. The atmosphere of 43 Cyg shows solar chemical composition at an effective temperature of 7150 $\pm$ 150 K, a log g of 4.2 $\pm$ 0.6 dex and a projected rotational velocity, $v {\rm sin}i$, of 44 $\pm$ 4 kms$^{-1}$. The morphology of the observed period spacing patterns shows indications of the presence of a significant chemical gradient in the stellar interior.