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Dorn-Wallenstein et al. utilized a novel machine-learning technique to classify a large sample of evolved massive stars. This resulted in new classifications for ∼2550 objects. We wish to validate the efficiency of the Dorn-Wallenstein et al. machine classifier. To this end we obtained new observations of four stars identified by Dorn-Wallenstein et al., with a focus on verifying newly identified emission-line objects and evolved supergiants. We identified a previously unconfirmed Be star, TYC 3740-1791-1, using these data. We assigned spectral types to the two stars in our sample with sufficient signal-to-noise data. We then used Gaia DR3 BP/RP spectra to validate an additional 73 stars from Dorn-Wallenstein et al. Our classifications support the completeness and contamination reported by the authors and confirm the validity of using machine learning-based classification methods on massive stars in the era of big data.

Fast yellow pulsating supergiants (FYPS) are a recently discovered class of evolved massive pulsators. As candidate supergiant objects, and one of the few classes of pulsating evolved massive stars, these objects have incredible potential to change our understanding of the structure and evolution of massive stars. Here we examine the lightcurves of a sample of 126 cool supergiants in the Magellanic Clouds observed by the Transiting Exoplanet Survey Satellite in order to identify pulsating stars. After making quality cuts and filtering out contaminant objects, we examine the distribution of pulsating stars in the Hertzprung–Russel (HR) diagram, and find that FYPS occupy a region above$\log L/L_{\odot }\gtrsim 5.0$. This luminosity boundary corresponds to stars with initial masses of ∼18–20M_⊙, consistent with the most massive red supergiant progenitors of supernovae (SNe) II-P, as well as the observed properties of SNe IIb progenitors. This threshold is in agreement with the picture that FYPS are post-RSG stars. Finally, we characterize the behavior of FYPS pulsations as a function of their location in the HR diagram. We find low-frequency pulsations at higher effective temperatures, and higher-frequency pulsations at lower temperatures, with a transition between the two behaviors at intermediate temperatures. The observed properties of FYPS make them fascinating objects for future theoretical study.

Using archival near-IR photometry, we identify 51 of theK-band brightest red supergiants (RSGs) in NGC 6822 and compare their physical properties with stellar evolutionary model predictions. We first use Gaia parallax and proper motion values to filter out foreground Galactic red dwarfs before constructing aJ–KversusKcolor–magnitude diagram to eliminate lower-mass asymptotic giant branch star contaminants in NGC 6822. We then cross match our results to previously spectroscopically confirmed RSGs and other NGC 6822 content studies and discuss our overall completeness, concluding that radial velocity alone is an insufficient method of determining membership in NGC 6822. After transforming theJandKmagnitudes to effective temperatures and luminosities, we compare these physical properties with predictions from both the Geneva single-star and Binary Population and Spectral Synthesis (BPASS) single and binary-star evolution tracks. We find that our derived temperatures and luminosities match the evolutionary model predictions well, however, the BPASS model, which includes the effects of binary evolution, provides the best overall fit. This revealed the presence of a group of cool RSGs in NGC 6822, suggesting a history of binary interaction. We hope this work will lead to further comparative RSG studies in other Local Group galaxies, opportunities for direct spectroscopic follow-up, and a better understanding of evolutionary model predictions.