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Accepted · first revision · record

Title: Physical calibration of convective overshoot and the mixing length
Plain: Stellar models describe convection, the boiling motion of hot gas, with a single adjustable length and add extra mixing past the convective boundary by hand. Different calibrations disagree, and the chosen values change derived stellar ages.
Precise: Mixing-length theory uses $\alpha_{\mathrm{MLT}}\sim 1.8$ calibrated on the Sun, and convective boundary mixing uses an overshoot extent of about 0.1 to 0.3 pressure scale heights. Determine whether $\alpha_{\mathrm{MLT}}$ is universal across mass, metallicity and evolutionary stage, and determine the overshoot extent and profile as a function of stellar mass, from 3D simulations validated against eclipsing binaries and asteroseismology.
Settled by: 3D convection simulations at realistic stellar parameters yielding a boundary-mixing law that fits eclipsing-binary and asteroseismic constraints across 1 to 10 $M_{\mathrm{sun}}$.
Kind: well-posed
Answer type: value
References: (empty)
Literature status: contested
Status note: Eclipsing-binary calibrations suggesting overshoot grows with mass have been disputed as a degeneracy with other model parameters.
Posed since: (empty)