Friday, September 18, 2026 at 12:15 pm

JILA Foothills Room

Tessa Frincke, Michigan State University

"3I/ATLAS: Our Most Recent Interstellar Interloper"

Abstract:

In the past decade, only three interstellar objects have been discovered traversing the inner Solar System:1I/`Oumuamua, 2I/Borisov, and 3I/ATLAS discovered in 2017, 2019, and 2025, respectively. Formed from the debris of planet formation, each object offers a unique window into the chemical compositions of planets outside of the Solar System. I will present near discovery imaging of 3I/ATLAS I obtained with the Southern Astrophysical Research Telescope (SOAR) and provide an overview of the global effort to observe 3I/ATLAS. Pre-perihelion measurements of chemical abundances indicated extreme surface processing in the interstellar medium by high energy galactic cosmic rays down into the surface layer of 3I/ATLAS. In this talk I will present an assessment of the erosion of the surface of 3I/ATLAS from outgassing to contextualize measured variations in chemical abundances throughout its trajectory. Interstellar objects are a growing class of objects that stand to provide invaluable insights into the formation of exoplanet systems that will bridge the gap between planetary and exoplanetary science.

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