Bethany Ludwig

Over the past few decades, our understanding of stars has evolved significantly. Not only have we been disabused of the notion that stars are predominately isolated systems, but we have also unveiled another astonishing truth: a majority of stars undergo interactions with binary companions throughout their lifetimes. The pervasive influence of binary evolution extends far beyond stellar astrophysics, casting profound implications across the entire spectrum of astrophysical disciplines.

The term "stripped stars," or intermediate-mass stripped helium stars, refers to massive stars that have had their outer hydrogen layers stripped away by a companion star. These helium cores of stars are extraordinarily hot and emit an abundance of ultraviolet light, leading to the identification of some of these systems through their distinctive "UV excess."

My colleagues and I employed modern techniques to construct an extensive catalog of UV photometry for the Magellanic Clouds, aimed at detecting this UV excess phenomenon. Our efforts resulted in the identification of thousands of potential candidates, and subsequently, we conducted follow-up spectroscopic observations on a select few at the Las Camanas Observatory in Chile.

We systematically identified the first stripped stars and conducted detailed modeling of their spectra to gain insights into their properties. Interestingly, some of these systems seem to be part of binary configurations with enigmatic "dark companions" that do not contribute to the optical spectra. These enigmatic companions are likely compact objects, and as such, these systems represent direct progenitors of currently detectable sources of gravitational waves.

Our ongoing work involves the analysis of extensive datasets acquired from the Hubble Space Telescope, Chandra X-Ray Observatory, and the Anglo-Australian Telescope, offering a wealth of new opportunities for exploration and discovery.