Physical interpretation of the oscillation spectrum on the RGB and AGB

Abstract

The high-frequency resolution of the four-year $\text{Kepler}$ time series allows detailed study of seismic modes in luminous giants. Seismic observables help infer interior structures via comparisons with stellar models. We aim to investigate differences between H-shell (Red-Giant Branch; RGB) and He-burning (red clump and Asymptotic-Giant Branch; AGB) stars in the He-II ionisation zone and the sensitivity of seismic parameters to input physics in stellar models. We used a grid of stellar models with masses $0.8-2.5M_{\odot }$ and metallicities $-1.0-0.25$dex, including mass loss, overshooting, thermohaline mixing, and rotation-induced mixing. P-mode frequencies were inferred by suppressing g-modes in the core. The main factors affecting seismic observables are stellar mass and metallicity. The He-II glitch amplitude in the local large frequency separation $\Delta \nu$ correlates with the He-II ionisation zone density, explaining observed differences between RGB and clump/AGB stars. That amplitude exceeds 10% of $\Delta \nu$ in high-luminosity giants, making the asymptotic expansion less accurate when $\Delta \nu \le 0.5\mu$Hz. Mass loss on the RGB and rotation-induced mixing from the main sequence to the early-AGB produce phase differences in the He-II glitch modulation signature between RGB and clump/AGB stars. Efficient RGB mass loss (for $M\le 1.5M_{\odot }$) and mixing processes (for $M\ge 1.5M_{\odot }$) leave detectable signatures in p-mode frequencies, enabling classification of red giants.

arXiv comment21 pages, 12 figures (8 in main text, 4 in appendices)

References in corpus (67)

• Modules for Experiments in Stellar Astrophysics (MESA)
• The Transiting Exoplanet Survey Satellite
• Modules for Experiments in Stellar Astrophysics (MESA): Giant Planets, Oscillations, Rotation, and Massive Stars
• Modules for Experiments in Stellar Astrophysics (MESA): Binaries, Pulsations, and Explosions
• MESA Isochrones and Stellar Tracks (MIST). I: Solar-Scaled Models
• Modules for Experiments in Stellar Astrophysics (MESA): Convective Boundaries, Element Diffusion, and Massive Star Explosions
• Modules for Experiments in Stellar Astrophysics (MESA): Pulsating Variable Stars, Rotation, Convective Boundaries, and Energy Conservation
• The K2 Mission: Characterization and Early results
• Gravity modes as a way to distinguish between hydrogen- and helium-burning red giant stars
• Kepler Asteroseismology Program: Introduction and First Results
• ADIPLS -- the Aarhus adiabatic oscillation package
• Testing Scaling Relations for Solar-Like Oscillations from the Main Sequence to Red Giants using Kepler Data
• Asteroseismology of old open clusters with Kepler: direct estimate of the integrated RGB mass loss in NGC6791 and NGC6819
• Thermohaline mixing: A physical mechanism governing the photospheric composition of low-mass giants
• The Second APOKASC Catalog: The Empirical Approach
• Calculating asteroseismic diagrams for solar-like oscillations
• Thermohaline instability and rotation-induced mixing. III - Grid of stellar models and asymptotic asteroseismic quantities from the pre-main sequence up to the AGB for low- and intermediate-mass stars at various metallicities
• Thermohaline instability and rotation-induced mixing. I - Low- and intermediate-mass solar metallicity stars up to the end of the AGB
• A Stellar Rotation Census of B Stars: from ZAMS to TAMS
• Solar-like oscillations in low-luminosity red giants: first results from Kepler
• Deep Mixing of He-3: Reconciling Big Bang and Stellar Nucleosynthesis
• Low-temperature gas opacity - AESOPUS: a versatile and quick computational tool
• Asteroseismology of red giants from the first four months of Kepler data: Global oscillation parameters for 800 stars
• Age dissection of the Milky Way discs: red giants in the Kepler field
• Period spacings in red giants II. Automated measurement
• The universal red-giant oscillation pattern; an automated determination with CoRoT data
• Asymptotic and measured large frequency separations
• Oscillations of alpha UMa and other red giants
• An asteroseismic signature of helium ionization
• Measuring the extent of convective cores in low-mass stars using Kepler data: towards a calibration of core overshooting
• Evolutionary influences on the structure of red-giant acoustic oscillation spectra from 600d of Kepler observations
• Measurement of acoustic glitches in solar-type stars from oscillation frequencies observed by Kepler
• Non-radial oscillations in M-giant semi-regular variables: Stellar models and Kepler observations
• Uncertainties on near-core mixing in red-clump stars: effects on the period spacing and on the luminosity of the AGB bump
• Thermohaline mixing in evolved low-mass stars
• Evidence for a sharp structure variation inside a red-giant star
• Period-luminosity relations in evolved red giants explained by solar-like oscillations
• Seismic diagnostics of red giants: first comparison with stellar models
• Helium abundance in a sample of cool stars: measurements from asteroseismology
• Deep Learning Classification in Asteroseismology
• Asteroseismic estimate of helium abundance of a solar analog binary system
• A new interpretation of the period-luminosity sequences of long-period variables
• Deep Learning Classification in Asteroseismology Using an Improved Neural Network: Results on 15000 Kepler Red Giants and Applications to K2 and TESS Data
• Asteroseismic Signatures of Small Convective Cores
• Seismic analysis of the second ionization region of helium in the Sun: I. Sensitivity study and methodology
• New light on the Gaia DR2 parallax zero-point: influence of the asteroseismic approach, in and beyond the Kepler field
• Kepler red-clump stars in the field and in open clusters: constraints on core mixing
• Solar-like oscillations of semiregular variables
• Thermohaline instability and rotation-induced mixing II- Yields of 3He for low- and intermediate-mass stars
• The Red-Giant Branch Bump Revisited: Constraints on Envelope Overshooting in a Wide Range of Masses and Metallicities
• Prospects for asteroseismic inference on the envelope helium abundance in red giant stars
• Helium signature in red giant oscillation patterns observed by Kepler
• Asteroseismology of luminous red giants with Kepler I: Long Period Variables with radial and non-radial modes
• Nonlinear seismic scaling relations
• On the asymptotic acoustic-mode phase in red-giant stars and its dependence on evolutionary state
• Surface effects on the red giant branch
• Modelling a high-mass red giant observed by CoRoT
• Seismic detection of acoustic sharp features in the CoRoT target HD49933
• Seismic signature of envelope penetrative convection: the CoRoT star HD 52265
• Seismic performance
• Asteroseismology of luminous red giants with Kepler. II. Dependence of mass loss on pulsations and radiation
• Comprehensive stellar seismic analysis : New method exploiting the glitches information in solar-like pulsators
• Seismic constraints on the internal structure of evolved stars: From high-luminosity RGB to AGB stars
• Adiabatic solar-like oscillations in red giant stars
• Properties of the ionisation glitch: I. Modelling the ionisation region
• Characterising the AGB bump and its potential to constrain mixing processes in stellar interiors
• Properties of the ionisation glitch II. Seismic signature of the structural perturbation