RSAA Colloquia / Seminars / Feast-of-Facts: Thursday, 27 March 2025, 11:00-12:00; ZOOM or Duffield Lecture Theatre


Heran Xiong

"Hot subdwarf stars and related stellar objects: modelling and empirical effective temperatures (End-of-thesis talk)"

Hot subdwarf stars are compact, high-temperature stars that serve as key laboratories for studying stellar evolution, asteroseismology, and binary interactions. In my PhD thesis, I present both theoretical and observational work to study hot subdwarfs across their full mass range and their implications for explaining unusual stellar objects. Among these are the mysterious Blue Large-Amplitude Pulsators, a newly discovered class of pulsators. I show that Shell-Helium-Burning hot subdwarfs are strong candidates to explain this class, outperforming other models proposed so far. I also present insights from the discovery and characterization of J0526, a short-period hot subdwarf binary, confirming it as the smallest known non-degenerate star in a detached binary system. Further, I explore white dwarf merger outcomes, specifically various Helium, CO and ONe white dwarf mergers, and demonstrate success in explaining recently observed phenomena, such as the Gaia Q Branch and the exceptionally massive stellar remnant J005311 with unusual spectral properties. Finally, I discuss my extension of the Infrared Flux Method to hot subdwarfs, incorporating ultraviolet and optical photometry, and its implications for GALEX photometry.