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tokens: HD 269902 (bottom). In HD 269902, most of the power in the WWZ is contained in the lower frequencies where the stochastic low-frequency background dominates—unsurprisingly given that the star has the second largest value of α out of the five FYPS (0.024 ± 0.001). Only by altering the scaling of the image of the WWZ are we able to see the ridge associated with the lowest-frequency peak, and it is only detected with low S/N. In both stars, the lowest-frequency peak in the RPS is associated with a broad band of power in the WWZ, similar to the WWZ of HD 269953, with a secondary band appearing at day −1 in HD 269840, at the approximate location of the highest peak in the RPS. 4. Discussion 4.1. Asteroseismic Modeling The discovery of fast pulsations in YSGs has very interesting implications for the study of the interiors of evolved massive stars. The 25 M ⊙ solar metallicity Geneva model (Ekström et al. 2012 ) has a main-sequence lifetime of approximately 7 Myr. It then crosses the H-R diagram in under 1 Myr, and half a Myr later, has evolved bluewards once more to become a Wolf–Rayet star (Massey et al. 2017 ). Due to the incredibly short lifetime of YSGs on both crossings of the H-R diagram, theoretical uncertainty has long stymied our understanding of massive star evolution (Kippenhahn Weigert 1990 ). Pulsation frequencies extracted from long-baseline lightcurves assembled from space-based observations are perhaps the most precise measurements we can make; typical values of for frequencies listed in Tables A1 – A5 are . In better-studied stars, such precision allows for the diagnosis of incredibly complicated physics and is truly the benchmark of testing stellar evolution theory (Aerts 2019 ). No asteroseismic models for YSGs that reliably converge exist (Jeffery Saio 2016 ), so the era of precision YSG asteroseismology is not yet upon us. However, we can compare the frequencies observed in the FYPS with the characteristic Lamb and Brunt–Väisälä angular frequencies in a model YSG: where l is the harmonic degree, c s is the sound speed, r is the radius of the local shell, g is the gravity, and the remaining variables are defined as in Aerts et al. ( 2010 ). Modes with angular frequencies and are mostly restored by pressure ( p -modes), and modes with and are mostly restored by buoyancy ( g -modes). While rudimentary, such a comparison would illustrate the approximate regions of the stellar structure the observed pulsations will allow us to probe. To do this, we use version 12778 of Modules for Experiments in Stellar Astrophysics (MESA, Paxton et al. 2011 , 2013 , 2015 , 2018 , 2019 ) to evolve a grid of nonrotating stellar models with initial masses between 15 and 30 M ⊙ , with a spacing of 1 M ⊙ , initial metallicity set to Z = 0.006, and initial helium mass fraction set to . We first evolve the models through the entire pre-main-sequence stage until the entirety of the star’s luminosity comes from nuclear burning and then introduce more