Work

Unusual polarimetric response of interstellar Comet 3I/ATLAS: clues to the microphysics of particles populating its inner coma

Year: 2025

Type: article

Abstract: ABSTRACT Using highly irregular agglomerated debris particles, we analyse the polarimetric observations of the second interstellar Comet 3I/ATLAS beyond the snow line. Unlike the vast majority of Solar system comets at shorter heliocentric distance, modelling of the polarization of the inner coma in Comet 3I/ATLAS necessarily requires water-ice particles (30–40 per cent by volume). Our modelling suggests the other two species to be Mg-rich silicate and organics/amorphous carbon, which are common for Solar system comets. The relative abundance of the Mg-rich silicates is lower than what was needed in modelling the polarization of Solar system comets. The modelling suggests that if Comet 3I/ATLAS were to keep its activity at heliocentric distances smaller than that of the snow line, it would be an extremely high Pmax comet with Pmax ≈ 36–40 per cent in red light.

Source: Monthly Notices of the Royal Astronomical Society Letters

DOI: 10.1093/mnrasl/slaf112

Authors: Evgenij Zubko, Gorden Videen

Institutions: University of Helsinki, Helsinki Institute of Physics, Space Science Institute, Kyung Hee University

Language: English

Topic: Astro and Planetary Science

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $1,451

Funder: National Aeronautics and Space Administration