Modelling $δ$ Scuti pulsations: A new grid of p, g, and f modes across pre-main-sequence to post-main-sequence evolution

Abstract

Space-based photometry reveals regular high-frequency patterns in many young $δ$ Scuti stars. These pulsations provide a powerful means of inferring stellar properties, particularly ages, for young $δ$ Scuti stars for which traditional age-dating methods are poorly constrained. Realising this potential requires theoretical models that capture the complexities of stellar structure and evolution. We present a comprehensive grid of 25 million stellar pulsation models, computed using the mesa stellar evolution code and the gyre stellar oscillation code, tailored to $δ$ Scuti stars. The grid spans a wide range of masses, metallicities and rotation velocities, and covers evolutionary phases from the early pre-main-sequence through the main sequence and into the post-main sequence contraction phase. For each model, we computed adiabatic pulsation frequencies for degrees $\ell$ = 0 to 3, capturing p modes, g modes, f modes and their interactions through avoided crossings. We find that f and low-order g modes have mode inertias comparable to or lower than the fundamental radial mode during the late pre-MS and early MS, implying that these modes should be observable. We revisit $δ$ Scuti scaling relations and map asteroseismic observables, including the large frequency separation ($Δν$) and phase offset parameter ($\varepsilon$), across age, mass, metallicity, and rotation. This new model grid, which is publicly available, improves upon previous such model grids by facilitating interpretation of $δ$ Scuti pulsations, allowing for more reliable age estimates and tighter constraints on stellar evolutionary pathways, and planet formation in A- and F-type stars.