One hundred years ago, the British astrophysicist Sir Arthur Eddington wrote that “Our telescopes may probe farther and farther into space, but they cannot penetrate a solid boulder; and the surface of a star acts as an equally impenetrable shield hiding all that goes on beneath.”

This would seem to suggest that stellar interiors are forever hidden from empirical scrutiny. However, the late decades of the 20th century saw the development of a new technique — “asteroseismology” — that overturns this notion. Asteroseismology uses measurements of waves on the surface of stars to place constraints on interior stellar structure, much like a seismologist uses measurements of earthquakes to probe the internal structure of the Earth.

In this talk, I’ll explain the physics underlying asteroseismology, describe the techniques used to map observations into structural constraints, and then highlight some of the remarkable results — in part, driven by NASA’s Kepler and TESS missions — that have flowed from the application of asteroseismology to stars throughout the galaxy and beyond.

Rich Townsend’s interest in stars developed at an early age, inspired by his maternal grandfather taking him outside on cold winter nights to look at the sky through a small bird-watching telescope. He majored in Physics at the University of Oxford (class of 1994), and then completed his doctorate in Astronomy at University College London (1997), where he specialised in asteroseismolgy of hot, luminous stars. After a year away from academia, he returned to UCL to undertake postdoctoral research. He moved to the USA in 2003, and then to Madison in 2008, where he joined the faculty in the UW Department of Astronomy. Since then, his research has mostly focused on developing open-source software for simulating the structure and evolution of stars, and for calculating the asteroseismic signatures of stellar models.

Location: Theater 300, Memorial High School. Directions here.

This meeting will be live-streamed via our Youtube Channel.