Monday, February 16, 2026 at 3:30 pm

JILA Foothills Room

Meridith Joyce, University of Wyoming

"How to Find a Star by Accident, or How Not to Solve the "Great Dimming" of Betelgeuse"

Abstract:

Alpha Orionis, popularly known as Betelgeuse, is a nearby red supergiant star visible to the naked eye. In light of the star's "Great Dimming"—a sudden, extreme drop in brightness that occurred in early 2020—a recent controversy surrounding Betelgeuse concerned whether it would explode as a supernova within the next few years, centuries, or millennia. Using a series of numerical techniques including one-dimensional stellar evolution models, hydrodynamic simulations, linear oscillation calculations, Fourier analysis, and the methods of a subfield of stellar astrophysics known as asteroseismology, my collaborators and I constrained the timeline for Betelgeuse's demise and revised many of the best estimates for its fundamental properties. In doing so, we discovered not only that Betelgeuse was not likely to undergo an imminent detonation, but that a pulsation signal unexplained by our models was, in fact, the signature of an as-yet-undiscovered binary companion. Its presence was confirmed earlier this year. What we never managed to do was explain the Great Dimming.

In this talk, I will use the story of the discovery of Betelgeuse’s hidden, low-mass binary companion, Alpha Orionis B—affectionately nicknamed “Betelbuddy”—both to highlight the computational and numerical techniques employed in modern stellar astrophysics and to illustrate how the most meaningful discoveries often arise not from confirming what we set out to find, but from venturing down the rabbit holes of unexpected problems that emerge along the way.

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