SLC of comet 3I/ATLAS. The MPC observations show a much larger dispersion of the data than the COBS observations. There is a significant increase in brightness starting at -45 days before perihelion that we interpreted as the onset of water sublimation. The maximum reduced magnitude reached by the comet was mV(max)=6.8±0.15 mag. This plot and the next one may be considered as two of the highlights of the SLC Methodology. The other highlight is the Comet Evolutionary Diagram. — astro-ph.EP
In this work we will create the Secular Light Curve (SLC) of exocomet 3I/ATLAS, using the SLC-Methodology (Ferrin 2010-2023). The SLCs give a throve of new information and allow the comparison of exo-comets with comets of our own solar system.
We arrive at the following conclusions: The colors of 3I are consistent and lie inside the area of colors of other comets in our solar system. The SLC of this comet exhibits a photometric anomaly, a region from -120 to -45 days before perihelion that we interpreted as an eclipse, suggesting that 3I might also be a binary.
At -45 days, the SLC changes abruptly its slope, reaching a maximum absolute magnitude of mV(1,1,α) = 6.8+-0.1. Using reported estimates derived from 97 papers in the arXiv.org depository for the size, dust, H2O, CO2, and CO production rates, we calculate the total mass loss. We use the inverse total mass loss, as a proxy for age.
The Mass-Loss Age = 0.16 comet years will be plotted in the horizontal axis of a Comet Evolutionary Diagram (CED) while the number of Remaining Returns defined as RR = r∆r = 24, will be plotted in the vertical axis of the CED. 3I/ATLAS exocomet lies among the comets of our Oort comet family.
We conclude that 3I is a comet of the Oort Cloud, but from a different stellar system. The Evolutionary Diagram presented in this work shows complexity beyond current understanding.
Ignacio Ferrin, Jose Garrido, Charles Triana, Giuliat Navas, Raul Melia, Santiago Perez, Emiliano Gomez, Jorge Andrey Vargas, Juan Hincapie, Brayan Quintero
Comments: 38 pages, 3 tables, 20 figures, 65 references
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2604.09941 [astro-ph.EP] (or arXiv:2604.09941v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2604.09941
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Submission history
From: Ignacio Ferrin
[v1] Fri, 10 Apr 2026 22:40:18 UTC (1,543 KB)
https://arxiv.org/abs/2604.09941
Astrobiology,