The Properties of Fast Yellow Pulsating Supergiants: FYPS Point the Way to Missing Red Supergiants

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