Laura Rogers (NOIRLab)
The White Dwarf Opportunity: Which Rocks and Minerals Make Up a Planet? We are in a golden era of rocky exoplanet discovery, yet fundamental questions remain about what these planets are made of and how their interiors and surfaces might support habitability. White dwarfs that exhibit atmospheric 'pollution' from accreted planetary material offer a unique opportunity to address these questions. By analysing optical and ultraviolet spectra of polluted white dwarf atmospheres, we can determine the bulk elemental composition of the accreted exoplanetary bodies. Meanwhile, infrared observations of circumstellar dust around the same stars can reveal the mineralogy of the disrupted planetary debris. In this talk, I will explore how polluted white dwarf systems provide insights into both the chemical and mineralogical makeup of rocky exoplanetary bodies. I will highlight emerging trends from abundance studies, discuss the link between elemental composition and mineralogy, and consider the implications for planetary formation, diversity, and habitability.

Ryan Lau (NOIRLab)
Revealing a Main-sequence Star that Consumed a Planet with JWSTThe subluminous red nova (SLRN) Zwicky Transient Facility (ZTF) SLRN-2020 is the most compelling direct detection of a planet being consumed by its host star, a scenario known as a planetary engulfment event. In this talk, I will present JWST spectroscopy of ZTF SLRN-2020 taken +830 days after its optical emission peak using the NIRSpec fixed-slit 3–5 μm high-resolution grating and the MIRI 5–12 μm low-resolution spectrometer. NIRSpec reveals the 12CO fundamental band (ν = 1–0) in emission at ~4.7 μm, Brackett-α emission, and the potential detection of PH3 in emission at ∼4.3 μm. The JWST spectra are consistent with the claim that ZTF SLRN-2020 arose from a planetary engulfment event. From a late-time spectral energy distribution (SED) model, we measure a luminosity of ~0.3 L⊙ for the remnant host star, which is consistent with a ~0.7 M⊙ K-type star that should not yet have evolved off the main sequence. If ZTF SLRN-2020 was not triggered by stellar evolution, we suggest that the planetary engulfment was due to orbital decay from tidal interactions between the planet and the host star.