Forward Asteroseismic Modeling of Stars with a Convective Core from Gravity-mode Oscillations: Parameter Estimation and Stellar Model Selection

Aerts, C.; Molenberghs, Geert; Michielsen, Mathias; Pedersen, May G.; Björklund, R.; Johnston, C.; Mombarg, Joey S. G.; Bowman, D. M.; Buysschaert, B.; Pápics, P. I.; Sekaran, S.; Sundqvist, J. O.; Tkachenko, A.; Truyaert, Kevin; Reeth, T. Van; Vermeyen, E.

doi:10.3847/1538-4365/aaccfb

Cited by 105 publications

(177 citation statements)

References 159 publications

(262 reference statements)

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“…These parameters were chosen as 'reasonable' for our targets; a full investigation of the influence of each parameter is beyond the scope of this paper. Interested readers are directed to Aerts et al (2018) and references therein. The tracks were computed for the mass range 1.0-3.0 M , at intervals of 0.05 M , and include T eff , log L, log g and age at 600 steps.…”

Section: Calculation Of Evolutionary Tracksmentioning

confidence: 99%

Gaia-derived luminosities ofKeplerA/F stars and the pulsator fraction across the δ Scuti instability strip

Murphy

Hey

Reeth

et al. 2019

Monthly Notices of the Royal Astronomical Society

155

169

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We study the fraction of stars in and around the δ Scuti instability strip that are pulsating, using Gaia DR2 parallaxes to derive precise luminosities. We classify a sample of over 15 000 Kepler A and F stars into δ Sct and non-δ Sct stars, paying close attention to variability that could have other origins. We find that 18 per cent of the δ Sct stars have their dominant frequency above the Kepler long-cadence Nyquist frequency (periods < 1 hr), and 30 per cent have some super-Nyquist variability. We analyse the pulsator fraction as a function of effective temperature and luminosity, finding that many stars in the δ Sct instability strip do not pulsate. The pulsator fraction peaks at just over 70 per cent in the middle of the instability strip. The results are insensitive to the amplitude threshold used to identify the pulsators. We define a new empirical instability strip based on the observed pulsator fraction that is systematically hotter than theoretical strips currently in use. The stellar temperatures, luminosities, and pulsation classifications are provided in an online catalogue.

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Section: Calculation Of Evolutionary Tracksmentioning

confidence: 99%

Gaia-derived luminosities ofKeplerA/F stars and the pulsator fraction across the δ Scuti instability strip

Murphy

Hey

Reeth

et al. 2019

Monthly Notices of the Royal Astronomical Society

155

169

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“…This requires dedicated asteroseismic modelling tools suitable to interpret the measured frequencies. Here, we explore and apply aspects of the methodology developed specifically for gravito-inertial modes by Aerts et al (2018). We first highlight relevant properties of the asteroseismic grids upon which we rely and subsequently exploit the probing power of the three observables (Π 0 , T eff , log g).…”

Section: Gravity-mode Period Spacingsmentioning

confidence: 99%

Asteroseismic masses, ages, and core properties of γ Doradus stars using gravito-inertial dipole modes and spectroscopy

Mombarg

Reeth

Pedersen

et al. 2019

Monthly Notices of the Royal Astronomical Society

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119

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The asteroseismic modelling of period spacing patterns from gravito-inertial modes in stars with a convective core is a high-dimensional problem. We utilise the measured period spacing pattern of prograde dipole gravity modes (acquiring Π 0 ), in combination with the effective temperature (T eff ) and surface gravity (log g) derived from spectroscopy, to estimate the fundamental stellar parameters and core properties of 37 γ Doradus (γ Dor) stars whose rotation frequency has been derived from Kepler photometry. We make use of two 6D grids of stellar models, one with step core overshooting and one with exponential core overshooting, to evaluate correlations between the three observables Π 0 , T eff , and log g and the mass, age, core overshooting, metallicity, initial hydrogen mass fraction and envelope mixing. We provide multivariate linear model recipes relating the stellar parameters to be estimated to the three observables (Π 0 , T eff , log g). We estimate the (core) mass, age, core overshooting and metallicity of γ Dor stars from an ensemble analysis and achieve relative uncertainties of ∼ 10 per cent for the parameters. The asteroseismic age determination allows us to conclude that efficient angular momentum transport occurs already early on during the main sequence. We find that the nine stars with observed Rossby modes occur across almost the entire main-sequence phase, except close to core-hydrogen exhaustion. Future improvements of our work will come from the inclusion of more types of detected modes per star, larger samples, and modelling of individual mode frequencies.

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“…Such criteria exists from information theory and we used the Bayesian information criterion (BIC; Schwarz 1978) to select the best model for each target. This criteria aims to infer the model that fits the data the best without over fitting and is used in several studies of stellar physics to infer the most likely model that reproduce the data from a set of different models (e.g., Degroote et al 2009;Aerts et al 2018;Matrà et al 2019). The BIC criteria was developped for model inference and is more conservative in the choice of the most likely model (higher penalty for models with more parameters to fit) than the Akaike information criterion (AIC) that was developed for prediction purposes.…”

Section: Strategymentioning

confidence: 99%

“…However, the differences between the BIC values for a given dataset can be small and several models can be considered. Usually, models with a difference of more than 10 with the BIC of the best model can be ruled out whereas a difference between 10 and 6 can be considered as moderately strong evidence for the best model, between 6 and 2 as positive evidence in favour of the best model and less than 2 as weak evidence (e.g., Aerts et al 2018).…”

Section: Strategymentioning

confidence: 99%

VLTI/PIONIER survey of disks around post-AGB binaries

Kluska

Winckel

Hillen

et al. 2019

A&A

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Context. Post-AGB binaries are surrounded by circumbinary disks of gas and dust that are similar to protoplanetary disks found around young stars. Aims. We aim to understand the structure of these disks and identify the physical phenomena at play in their very inner regions. We want to understand the disk-binary interaction and to further investigate the comparison with protoplanetary disks. Methods. We have conducted an interferometric snapshot survey of 23 post-AGB binaries in the near-infrared (H-band) using VLTI/PIONIER. We have fitted the multiwavelength visibilities and closure phases with purely geometrical models with an increasing complexity (including two point-sources, an azimuthally modulated ring and an over-resolved flux) in order to retrieve the sizes, temperatures and flux ratios of the different components.Results. All sources are resolved and the different components contributing to the H-band flux are dissected. The environment of these targets is very complex: 13/23 targets need models with thirteen or more parameters to fit the data. We find that the inner disk rims follow and extend the size-luminosity relation established for disks around young stars with an offset toward larger sizes. The measured temperature of the near-infrared circumstellar emission of post-AGB binaries is lower (T sub ∼1200 K) than for young stars, probably due to a different dust mineralogy and/or gas density in the dust sublimation region. Conclusions. The dusty inner rims of the circumbinary disks around post-AGB binaries are ruled by dust sublimation physics. Additionally a significant amount of the circumstellar H-band flux is over-resolved (14 targets have more than 10% of their non-stellar flux over-resolved) hinting for more structure from a yet unknown origin (disk structure or outflow). The amount of over-resolved flux is larger than around young stars. Due to the complexity of these targets, interferometric imaging is a necessary tool to reveal the interacting inner regions in a model-independent way.

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Forward Asteroseismic Modeling of Stars with a Convective Core from Gravity-mode Oscillations: Parameter Estimation and Stellar Model Selection

Cited by 105 publications

References 159 publications

Gaia-derived luminosities ofKeplerA/F stars and the pulsator fraction across the δ Scuti instability strip

Gaia-derived luminosities ofKeplerA/F stars and the pulsator fraction across the δ Scuti instability strip

Asteroseismic masses, ages, and core properties of γ Doradus stars using gravito-inertial dipole modes and spectroscopy

VLTI/PIONIER survey of disks around post-AGB binaries

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