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Register a new userAsteroseismic modelling of the Binary HD 176465
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The detection and analysis of oscillations in binary star systems is critical in understanding stellar structure and evolution. This is partly because such systems have the same initial chemical composition and age. Solar-like oscillations have been detected by Kepler in both components of the asteroseismic binary HD 176465. We present an independent modelling of each star in this binary system. Stellar models generated using MESA (Modules for Experiments in Stellar Astrophysics) were fitted to both the observed individual frequencies and complementary spectroscopic parameters. The individual theoretical oscillation frequencies for the corresponding stellar models were obtained using GYRE as the pulsation code. A Bayesian approach was applied to find the probability distribution functions of the stellar parameters using AIMS (Asteroseismic Inference on a Massive Scale) as the optimisation code. The ages of HD 176465 A and HD 176465 B were found to be 2.81 $pm$ 0.48 Gyr and 2.52 $pm$ 0.80 Gyr, respectively. These results are in agreement when compared to previous studies carried out using other asteroseismic modelling techniques and gyrochronology.
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Binary star systems are important for understanding stellar structure and evolution, and are especially useful when oscillations can be detected and analysed with asteroseismology. However, only four systems are known in which solar-like oscillations are detected in both components. Here, we analyse the fifth such system, HD 176465, which was observed by Kepler. We carefully analysed the systems power spectrum to measure individual mode frequencies, adapting our methods where necessary to accommodate the fact that both stars oscillate in a similar frequency range. We also modelled the two stars independently by fitting stellar models to the frequencies and complementary parameters. We are able to cleanly separate the oscillation modes in both systems. The stellar models produce compatible ages and initial compositions for the stars, as is expected from their common and contemporaneous origin. Combining the individual ages, the system is about 3.0$pm$0.5 Gyr old. The two components of HD 176465 are young physically-similar oscillating solar analogues, the first such system to be found, and provide important constraints for stellar evolution and asteroseismology.
The satellite CoRoT (Convection, Rotation, and planetary Transits) has provided high-quality data for almost six years. We show here the asteroseismic analysis and modeling of HD169392A, which belongs to a binary system weakly gravitationally bound as the distance between the two components is of 4250 AU. The main component, HD169392A, is a G0IV star with a magnitude of 7.50 while the second component is a G0V-G2IV star with a magnitude of 8.98. This analysis focuses on the main component, as the secondary one is too faint to measure any seismic parameters. A complete modeling has been possible thanks to the complementary spectroscopic observations from HARPS, providing Teff=5985+/-60K, log g=3.96+/-0.07, and [Fe/H]=- 0.04+/-0.10.
We present the results of analysis and modelling of the eclipsing binary system, KIC 10661783. The Fourier analysis of the Kepler light curve, corrected for the binary effects, reveals 750 frequency peaks in both p and g-mode regions. Those with the highest amplitudes concentrate in the range of 20-30 d$^{-1}$. To reproduce observed spectrum of frequencies we construct seismic models accounting for the mode instability. In order to obtain instabilities in the g-mode regime we modify the opacity tables data near the Z-bump. In order to reproduce system parameters, we construct evolutionary models including binary evolution.
Context. Asteroseismology is an effcient tool not only for testing stellar structure and evolutionary theory but also constraining the parameters of stars for which solar-like oscillations are detected, presently. As an important southern asteroseismic target, Tau Ceti, is a metal-poor star. The main features of the oscillations and some frequencies of ? Ceti have been identified. Many scientists propose to comprehensively observe this star as part of the Stellar Observations Network Group. Aims. Our goal is to obtain the optimal model and reliable fundamental parameters for the metal-poor star Tau Ceti by combining all non-asteroseismic observations with these seismological data. Methods. Using the Yale stellar evolution code (YREC), a grid of stellar model candidates that fall within all the error boxes in the HR diagram have been constructed, and both the model frequencies and large- and small- frequency separations are calculated using the Guenthers stellar pulsation code. The chi2c minimization is performed to identify the optimal modelling parameters that reproduce the observations within their errors. The frequency corrections of near-surface effects to the calculated frequencies using the empirical law, as proposed by Kjeldsen and coworkers, are applied to the models. Results. We derive optimal models, corresponding to masses of about 0.775 - 0.785 M? and ages of about 8 - 10 Gyr. Furthermore, we find that the quantities derived from the non-asteroseismic observations (effective temperature and luminosity) acquired spectroscopically are more accurate than those inferred from interferometry for ? Ceti, because our optimal models are in the error boxes B and C, which are derived from spectroscopy results.
The Transiting Exoplanet Survey Satellite (TESS) is recording short-cadence, high duty-cycle timeseries across most of the sky, which presents the opportunity to detect and study oscillations in interesting stars, in particular planet hosts. We have detected and analysed solar-like oscillations in the bright G4 subgiant HD 38529, which hosts an inner, roughly Jupiter-mass planet on a 14.3 d orbit and an outer, low-mass brown dwarf on a 2136 d orbit. We combine results from multiple stellar modelling teams to produce robust asteroseismic estimates of the stars properties, including its mass $M = 1.48 pm 0.04 mathrm{M}_odot$, radius $R = 2.68 pm 0.03 mathrm{R}_odot$ and age $t = 3.07 pm 0.39 ,mathrm{Gyr}$. Our results confirm that HD 38529 has a mass near the higher end of the range that can be found in the literature and also demonstrate that precise stellar properties can be measured given shorter timeseries than produced by CoRoT, Kepler or K2.
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