Colloquium – Lyra Cao

Lyra Cao, Vanderbilt University

The ROle of magnetic starspots in modern stellar astrophysics

Stars are essential to much of astrophysics—whether as building blocks of galaxies, as courteous or cranky hosts to planets, or even as companions to more exotic objects. Our precise understanding of stellar behavior is therefore critical to understanding much of astrophysics, and it plays a major role in realizing the science goals of many upcoming ground- and space-based missions. However, tensions exist in stellar models for many astrophysical observables, a problem which has limited our ability to interpret data and test the underlying physics of such models. Such tensions include the anomalously large radii of active stars relative to models, the unexpected behavior of light element abundances on the surfaces of young stars, and the strange behaviors in the rotational spin-down of stars. These problems, originating from various different observables across stellar physics, appear to have a common link: they appear to be happening to “problem stars”, such as low-mass, young, and active stars. But could these anomalies have a common explanation in actuality?

In this talk, I explore a possible unique solution to these tensions and outline the theoretical and observational developments which made it possible. I introduce techniques to model the impact of magnetism in stars, and to measure signatures of stellar magnetism from large astrophysical datasets. I outline the discovery space of this observable, the possible new tests of stellar physics that it enables, and its potential for improving stellar characterization pipelines. I describe the impact that the inclusion of stellar magnetism has for our existing theories of stellar evolution, and on fields which rely on accurate stellar models. Finally, I explore the synergies that magnetic evolutionary models and large magnetic datasets may have for anticipated astrophysical programs.

BIO: Lyra Cao is a VIDA postdoctoral fellow in Prof. Keivan Stassun’s group at Vanderbilt University, studying stellar evolution, stellar magnetism and activity, stellar rotation, and starspots. Lyra received a Ph.D. in astronomy at the Ohio State University in 2023, working with Prof. Marc Pinsonneault on the thesis, “Starspots and the Magnetic Lives of Stars”.

March 20, 2025 @ 4:10pm Central in Stevenson 4327