Mixed Mode Asteroseismology of Red Giant Stars Through the Luminosity Bump

Abstract

Most current models of low mass red giant stars do not reproduce the observed position of the red giant branch luminosity bump, a diagnostic of the maximum extent of the convective envelope during the first dredge up. Global asteroseismic parameters, the large frequency separation and frequency of maximum oscillation power, measured for large samples of red giants, show that modeling convective overshoot below the convective envelope helps match the modeled luminosity bump positions to observations. However, these global parameters cannot be used to probe envelope overshoot in a star-by-star manner. Red giant mixed modes, which behave like acoustic modes at the surface and like gravity modes in the core, contain important information about the interior structure of the star, especially near the convective boundary. Therefore, these modes may be used to probe interior processes, such as overshoot. Using a grid of red giant models with varying mass, metallicity, surface gravity, overshoot treatment, and amount of envelope overshoot, we find that changing the overshoot amplitude (and prescription) of overshoot below the convection zone in red giant stellar models results in significant differences in the evolution of the models' dipole mixed-mode oscillation frequencies, the average mixed mode period spacing, $⟨\Delta P⟩$, and gravity mode phase offset term, ${\epsilon }_g$.

arXiv comment19 pages, 16 figures. Accepted for publication in ApJ April 18 2022

References in corpus (40)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• 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
• 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
• Gravity modes as a way to distinguish between hydrogen- and helium-burning red giant stars
• GYRE: An open-source stellar oscillation code based on a new Magnus Multiple Shooting Scheme
• The Thirteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey MApping Nearby Galaxies at Apache Point Observatory
• The Cannon: A data-driven approach to stellar label determination
• The APOKASC Catalog: An Asteroseismic and Spectroscopic Joint Survey of Targets in the Kepler Fields
• The Second APOKASC Catalog: The Empirical Approach
• Red giant masses and ages derived from carbon and nitrogen abundances
• Theoretical amplitudes and lifetimes of non-radial solar-like oscillations in red giants
• Tracing chemical evolution over the extent of the Milky Way's Disk with APOGEE Red Clump Stars
• Giant star seismology
• Sub-Inertial Gravity Modes in the B8V Star KIC 7760680 Reveal Moderate Core Overshooting and Low Vertical Diffusive Mixing
• Period spacings in red giants I. Disentangling rotation and revealing core structure discontinuities
• The shape of convective core overshooting from gravity-mode period spacings
• Post first dredge-up [C/N] ratio as age indicator. Theoretical calibration
• Galactic Archaeology with asteroseismic ages. II. Confirmation of a delayed gas infall using Bayesian analysis based on MCMC methods
• Period spacings in red giants IV: Toward a complete description of the mixed-mode pattern
• Investigating the Metallicity-Mixing Length Relation
• Lithium depletion in solar-like stars: effect of overshooting based on realistic multi-dimensional simulations
• Probing the shape of the mixing profile and of the thermal structure at the convective core boundary through asteroseismology
• How Many Elements Matter?
• The Red-Giant Branch Bump Revisited: Constraints on Envelope Overshooting in a Wide Range of Masses and Metallicities
• On the red-giant luminosity bump
• The K2 Galactic Archaeology Program Data Release 3: Age-abundance patterns in C1-C8 and C10-C18
• Extreme value statistics for two-dimensional convective penetration in a pre-Main Sequence star
• Stellar convective penetration: parameterized theory and dynamical simulations
• Age-chemical abundance structure of the Galaxy I: Evidence for a late accretion event in the outer disc at z ~ 0.6
• Semi-analytic Expressions for the Isolation and Coupling of Mixed Modes
• Testing the asymptotic relation for period spacings from mixed modes of red giants observed with the Kepler mission
• The Helium Abundance of NGC 6791 from Modeling of Stellar Oscillations
• Lithium depletion in the sun: a study of mixing based on hydrodynamical simulations
• Evolution of the gravity offset of mixed modes in RGB stars
• Automated determination of g-mode period spacing of red-giant stars
• On the dynamics of overshooting convection in spherical shells: Effect of density stratification and rotation

Cited by in corpus (8)

• Asteroseismic measurement of core and envelope rotation rates for 2006 red giant branch stars
• Mode Mixing and Rotational Splittings: II. Reconciling Different Approaches to Mode Coupling
• Near-Core Acoustic Glitches are Not Oscillatory: Consequences for Asteroseismic Probes of Convective Boundary Mixing
• Acoustic modes in M67 cluster stars trace deepening convective envelopes
• TESS Asteroseismic Analysis of HD 76920: The Giant Star Hosting An Extremely Eccentric Exoplanet
• Pushing the boundaries of asteroseismic individual frequency modelling: unveiling two evolved very-low metallicity red giants
• Inferring the efficiency of convective-envelope overshooting in Red Giant Branch stars
• Realising efficient computation of individual frequencies for red-giant models