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Title: SUB-INERTIAL GRAVITY MODES IN THE B8V STAR KIC 7760680 REVEAL MODERATE CORE OVERSHOOTING AND LOW VERTICAL DIFFUSIVE MIXING
Authors: Moravveji, Ehsan ×
Townsend, Richard H. D
Aerts, Conny
Mathis, Stephane #
Issue Date: Jun-2016
Publisher: University of Chicago Press for the American Astronomical Society
Series Title: Astrophysical Journal vol:823 issue:2
Article number: 130
Abstract: Thus far, KIC 7760680 is the richest slowly pulsating B star, exhibiting 36 consecutive dipole (ℓ = 1) gravity (g-) modes. The monotonically decreasing period spacing of the series, in addition to the local dips in the pattern, confirm that KIC 7760680 is a moderate rotator with clear mode trapping in chemically inhomogeneous layers. We employ the traditional approximation of rotation to incorporate rotational effects on g-mode frequencies. Our detailed forward asteroseismic modeling of this g-mode series reveals that KIC 7760680 is a moderately rotating B star with mass ∼3.25 M ⊙. By simultaneously matching the slope of the period spacing and the number of modes in the observed frequency range, we deduce that the equatorial rotation frequency of KIC 7760680 is 0.4805 day‑1, which is 26% of its Roche break up frequency. The relative deviation of the model frequencies and those observed is less than 1%. We succeed in tightly constraining the exponentially decaying convective core overshooting parameter to f ov ≈ 0.024 ± 0.001. This means that convective core overshooting can coexist with moderate rotation. Moreover, models with exponentially decaying overshoot from the core outperform those with the classical step-function overshoot. The best value for extra diffusive mixing in the radiatively stable envelope is confined to {log}{D}{{ext}}≈ 0.75+/- 0.25 (with D ext in cm2 s‑1), which is notably smaller than theoretical predictions.
ISSN: 0004-637X
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Institute of Astronomy
× corresponding author
# (joint) last author

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