Beyond MESA Defaults: The Impact of Structural Resolution Uncertainty in <i>p</i> -mode Asteroseismology

Abstract Observations of pressure modes ( p -modes) in stars have enabled profound insights into stellar properties, and theoretical stellar evolution and oscillation models are integral to these inferences. However, modeling uncertainties are often overlooked, even as they can rival or exceed observational uncertainties. In this study, we quantify, for the first time, the impact of structural resolution choices in 1D stellar evolution calculations on predicted p -mode frequencies across the H-R diagram, using MESA and GYRE . We present demonstrative measurements of resolution-based modeling uncertainty for a range of solar-like, upper main-sequence, and Mira oscillators and compare these directly to TESS observational uncertainties. We demonstrate that resolution-driven uncertainties can significantly influence theoretical predictions and in some cases overwhelm observational uncertainties by orders of magnitude. For the illustrative case considered—an order-of-magnitude variation in mesh resolution—solar-like oscillators typically have fractional, resolution-based uncertainties at or below 1% of the test frequency. Fractional uncertainties in Miras, however, are as large as 20%. We also find that the location and morphology of the red giant branch bump and red clump are impacted substantially by resolution uncertainty. Stellar ages are impacted at the 10% level for young main-sequence stars, and the model-based correction factor for the Δ ν – <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msqrt> <mml:mrow> <mml:mi>ρ</mml:mi> </mml:mrow> </mml:msqrt> </mml:math> scaling relation is impacted at the 2% level. Our results underscore the need to incorporate modeling uncertainties into asteroseismic analyses and provide a reference framework for observers evaluating the reliability of theoretical models.