8 papers
Origin and evolution of NiI and FeI in the coma of the interstellar comet 3I/ATLAS throughout its trajectory
Damien Hutsemékers, Jean Manfroid, Cyrielle Opitom +8
We present high-resolution UVES+VLT observations of neutral nickel and iron atoms in the coma of the interstellar comet 3I/ATLAS taken after perihelion. Metal emission was strong s…
Activity and composition of periodic comets 67P/Churyumov-Gerasimenko and 103P/Hartley 2 at two different perihelion passages
E. Hemmen, M. Vander Donckt, E. Jehin +6
Through photometry and spectroscopy, we studied the evolution of the activity and chemical composition of comet 67P during its 2025 and 2021 perihelion passages and of comet 103P d…
High nitrogen and carbon isotopic ratios in the interstellar comet 3I/ATLAS
C. Opitom, J. Manfroid, D. Hutsemékers +13
Interstellar objects provide a unique opportunity to further our understanding of the planetary formation process by studying in detail material formed around another star. Their i…
Very Large Telescope Observations of Interstellar Comet 3I/ATLAS. II. From Quiescence to Glow: Dramatic Rise of Ni i Emission and Incipient CN Outgassing at Large Heliocentric Distances*
Rohan Rahatgaonkar, Juan Pablo Carvajal, Thomas H. Puzia +25
We report VLT spectroscopy of the interstellar comet 3I/ATLAS (C/2025~N1) from to ~au using X-shooter (300--550\,nm, ) and UVES (opt…
Ionic emissions and activity evolution in comet C/2020 F3 (NEOWISE): Insights from long-slit spectroscopy and photometry
K. Aravind, E. Jehin, S. Hmmidouch +7
Comet C/2020 F3 (NEOWISE) was the brightest comet in the northern hemisphere since C/1995 O1 (Hale-Bopp), providing a unique opportunity to study its composition and spatial distri…
Discovery and Preliminary Characterization of a Third Interstellar Object: 3I/ATLAS
Darryl Z. Seligman, Marco Micheli, Davide Farnocchia +44
We report initial observations aimed at the characterization of a third interstellar object. This object, 3I/ATLAS or C/2025 N1 (ATLAS), was discovered on 2025 July 1 UT and has an…