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Convective boundary mixing in low- and intermediate-mass stars I. Core properties from pressure-mode asteroseismology

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  • George C. Angelou, Max-Planck-Institut für Astrophysik, Max-Planck-Institut für Sonnensystemforschung
  • ,
  • Earl P. Bellinger
  • Saskia Hekker, Max-Planck-Institut für Sonnensystemforschung
  • ,
  • Alexey Mints, Max-Planck-Institut für Sonnensystemforschung, Leibniz Institute for Astrophyics Potsdam (AIP)
  • ,
  • Yvonne Elsworth, University of Birmingham
  • ,
  • Sarbani Basu, Department of Astronomy, Yale University, New Haven, Connecticut, USA
  • ,
  • Achim Weiss, Max-Planck-Institut für Astrophysik
Convective boundary mixing (CBM) is ubiquitous in stellar evolution. It is a necessary ingredient in the models in order to match observational constraints from clusters, binaries and single stars alike. We compute `effective overshoot' measures that reflect the extent of mixing and which can differ significantly from the input overshoot values set in the stellar evolution codes. We use constraints from pressure modes to infer the CBM properties of Kepler and CoRoT main-sequence and subgiant oscillators, as well as in two radial velocity targets (Procyon A and α Cen A). Collectively these targets allow us to identify how measurement precision, stellar spectral type, and overshoot implementation impact the asteroseismic solution. With these new measures we find that the `effective overshoot' for most stars is in line with physical expectations and calibrations from binaries and clusters. However, two F-stars in the CoRoT field (HD 49933 and HD 181906) still necessitate high overshoot in the models. Due to short mode lifetimes, mode identification can be difficult in these stars. We demonstrate that an incongruence between the radial and non-radial modes drives the asteroseismic solution to extreme structures with highly-efficient CBM as an inevitable outcome. Understanding the cause of seemingly anomalous physics for such stars is vital for inferring accurate stellar parameters from TESS data with comparable timeseries length.
OriginalsprogEngelsk
TidsskriftMonthly Notices of the Royal Astronomical Society
Vol/bind493
Nummer4
Sider (fra-til)4987–5004
Antal sider18
ISSN0035-8711
DOI
StatusUdgivet - apr. 2020

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