An Application Note: Registrability-Based Structural Classification of the Betelgeuse Dimming Event

The 2019–2020 Great Dimming of Betelgeuse prompted widespread speculation that the star was undergoing rapid evolutionary change or approaching terminal collapse. Subsequent multi-wavelength observations demonstrated that the event was dominated by dust formation and line-of-sight obscuration rather than intrinsic stellar instability. In this application note, we apply a registrability-based structural classification framework to the Betelgeuse dimming event. The framework enforces duration scaling, chromatic behavior, multi-channel registrability, geometric admissibility, recurrence, and identity-preservation constraints prior to astrophysical interpretation, explicitly separating loss of observability from loss of physical identity. Evaluation of the published observational record yields an unambiguous classification: Class IV — dust-dominated, incoherent registrability loss — with stellar identity preserved. Strong wavelength dependence, infrared persistence, lack of coherent occultation geometry, and post-event spectral recovery collectively exclude evolutionary transformation or terminal collapse. Betelgeuse serves as a resolved validation case for registrability-based classification, demonstrating how dramatic stellar dimming can be assessed conservatively and reproducibly without interpretive escalation. The framework provides a repeatable first-pass diagnostic for future apparent stellar “disappearance” events.