![CN production versus heliocentric distance: Blue circles show VLT/X-shooter measurements of 3I/ATLAS (this work); the black solid and gray dashed curves are power–law fits to the 3I data only, giving Q(CN) ∝ r −9.38±1.2 h (weighted) and Q(CN) ∝ r −9.14±1.57 h (unweighted), respectively. Colored symbols compare with Solar–system comets compiled from the literature, grouped by dynamical class as in the legend; green squares mark measurements for 2I/Borisov. The left axis gives log10[Q(CN)/atoms s−1 ] and the bottom axis in log-scale the heliocentric distance rh (au). The right axis shows an approximate equilibrium surface temperature T(rh). Horizontal dashed lines indicate sublimation thresholds for CO, NH3, CO2, and H2O. Other comets references: Manfroid et al. (2021), Opitom et al. (2016), Opitom et al. (2017), Opitom et al. (2019), Fitzsimmons et al. (2019), Rauer et al. (2003) and S -- astro-ph.SR](https://astrobiology.newspackstaging.com/wp-content/uploads/2025/08/VLT-Observations-Of-Interstellar.png)
We report VLT spectroscopy of the interstellar comet 3I/ATLAS (C/2025 N1) from rh≃4.4 to 2.85 au using X-shooter (300-550 nm, R≃3000) and UVES (optical, R≃35k−80k).
Posted inAstrochemistry, Astrogeology, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy
