Speaker
Description
Following ESA’s Rosetta mission to comet 67P/Churyumov-Gerasimenko (67P) from 2014-2016, we conducted hyperspectral observations with the Very Large Telescope’s (VLT) Multi-Unit Spectroscopic Explorer (MUSE) instrument during its 2021–2022 apparition. These observations span two seasons on 67P, and perihelion, enabling simultaneous mapping of the dust coma and gaseous species evolution, specifically: [OI]$^1$D (a proxy for H$_2$O), C$_2$, NH$_2$, and CN. We identify two dominant regimes in the coma's morphological evolution: (1) variable [OI]$^1$D and C$_2$ structures linked to nucleus-driven sublimation, and (2) more stable NH$_2$ and CN emissions associated with seasonal illumination, known dust structures, and likely extended sources. To explore the existence of extended sources, we applied radial Haser modeling on NH$_2$ and CN profiles, and computed spectral reflectivity maps from the dust coma. Pre-perihelion NH$_2$ from 67P’s north pole shows 1.5–1.9× longer effective photochemical scale lengths when compared with the rest of the coma, consistent with partial extended source production. Additionally, CN emission in the south coincides with a known dust fan whose spectral slope is 2–3× redder than the surrounding dust coma, suggesting the presence of larger or more organic-rich grains that may act as extended sources and contribute to CN production. This analysis serves as the foundational work for the broader MUSE comet survey, which includes over 30 comets spanning diverse heliocentric distances and dynamical classes. We aim to explore and compare the gas and dust morphologies for these comets, such that a deeper understanding of extended sources and their roles in comet comae can be ascertained.
