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

TL;DR

This paper introduces a comprehensive grid of 25 million stellar pulsation models for $\delta$ Scuti stars, covering various evolutionary stages, to improve interpretation of pulsations and enable more accurate stellar age and property estimations.

Contribution

A new, extensive grid of stellar pulsation models for $\delta$ Scuti stars across all evolutionary phases, incorporating rotation and metallicity effects, and publicly available for enhanced asteroseismic analysis.

Findings

f and low-order g modes are observable during late pre-MS and early MS

Revised $\delta$ Scuti scaling relations for age and stellar properties

Model grid enables more reliable age estimates and evolutionary constraints

Abstract

Space-based photometry reveals regular high-frequency patterns in many young $\delta$ Scuti stars. These pulsations provide a powerful means of inferring stellar properties, particularly ages, for young $\delta$ 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 $\delta$ 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 $\delta$ Scuti scaling relations and map asteroseismic observables, including the large frequency separation ($\Delta\nu$) 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 $\delta$ Scuti pulsations, allowing for more reliable age estimates and tighter constraints on stellar evolutionary pathways, and planet formation in A- and F-type stars.