Insights from the APOKASC Determination of the Evolutionary State of Red-Giant Stars by consolidation of different methods

Abstract

The internal working of low-mass stars is of great significance to both the study of stellar structure and the history of the Milky Way. Asteroseismology has the power to directly sense the internal structure of stars and allows for the determination of the evolutionary state -- i.e. has helium burning commenced or is the energy generated only by the fusion in the hydrogen-burning shell? We use observational data from red-giant stars in a combination (known as APOKASC) of asteroseismology (from the \textit{Kepler} mission) and spectroscopy (from SDSS/APOGEE). The new feature of the analysis is that the APOKASC evolutionary state determination is based on the comparison of diverse approaches to the investigation of the frequency-power spectrum. The high level of agreement between the methods is a strong validation of the approaches. Stars for which there is not a consensus view are readily identified. The comparison also facilitates the identification of unusual stars including those that show evidence for very strong coupling between p and g cavities. The comparison between the classification based on the spectroscopic data and asteroseismic data have led to a new value for the statistical uncertainty in APOGEE temperatures. These consensus evolutionary states will be used as an input for methods that derive masses and ages for these stars based on comparison of observables with stellar evolutionary models (`grid-based modeling') and as a training set for machine-learning and other data-driven methods of evolutionary state determination

19 pages, 10 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society

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Cited by in corpus (26)

• Age dissection of the Milky Way discs: red giants in the Kepler field
• APOKASC-3: The Third Joint Spectroscopic and Asteroseismic catalog for Evolved Stars in the Kepler Fields
• Discovery of post-mass-transfer helium-burning red giants using asteroseismology
• Age-Dating Red Giant Stars Associated with Galactic Disk and Halo Substructures
• Cannibals in the thick disk II -- Radial-velocity monitoring of the young alpha-rich stars
• The K2 Galactic Archaeology Program Data Release 2: Asteroseismic results from campaigns 4, 6, & 7
• A seismic scaling relation for stellar age II: The red giant branch
• Nature vs. Nurture: Distinguishing Effects from Stellar Processing and Chemical Evolution on Carbon and Nitrogen in Red Giant Stars
• The APO-K2 Catalog. II. Accurate Stellar Ages for Red Giant Branch Stars across the Milky Way
• Is Thermohaline Mixing the Full Story? Evidence for Separate Mixing Events near the Red Giant Branch Bump
• An Intermediate-age Alpha-rich Galactic Population in K2
• Characterizing Observed Extra Mixing Trends in Red Giants using the Reduced Density Ratio from Thermohaline Models
• Clumpiness: Time-domain classification of red-giant evolutionary states
• Unveiling the Structure and Dynamics of Red Giants with Asteroseismology
• Measuring frequency and period separations in red-giant stars using machine learning
• Lithium in Kepler Red Giants: Defining Normal and Anomalous
• Red giants evolutionary status determination: the complete Kepler catalog
• Advancing accuracy in age determinations of old-disk stars using an oscillating red giant in an eclipsing binary
• GaiaUnlimited: The old stellar disc of the Milky Way as traced by the Red Clump
• Power density spectra morphologies of seismically unresolved red-giant asteroseismic binaries
• The sensitivity and behaviour of the curvature in the échelle diagram of red-giant stars
• The highest mass Kepler red giants -- II. Spectroscopic parameters, the amplitude-activity relation, and unexpected halo orbits
• Red giant asteroseismic binaries in the Kepler field
• Towards Accurate Asteroseismic Masses for Luminous Giants
• Hidden oscillations in plain sight: identification of seismically unresolved red-giant asteroseismic binary candidates
• A 'Quick Look' at All-Sky Galactic Archeology with TESS: 158,000 Oscillating Red Giants from the MIT Quick-Look Pipeline