Dust colour, phase behaviour, and Monte Carlo modelling of interstellar Comet 3I/ATLAS from 4 au Pre- to 4 au post-perihelion
4 affiliations
- 1Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n , E-18008 Granada ,
- 2Instituto de Astrofísica de Canarias, C/Vía Láctea s/n , E-38205 La Laguna, Tenerife ,
- 3Light Bridges, Observatorio Astronómico del Teide. Carretera del Observatorio del Teide , s/n, Güímar, E-38500 Tenerife ,
- 4Universidad de La Laguna, Avda. Astrofísico Francisco Sánchez Departamento de Astrofísica, , E-38206 La Laguna, Tenerife ,
Abstract
We report multiband photometric imaging observations and Monte Carlo dust tail modelling of the interstellar comet 3I/ATLAS covering a wide range of heliocentric distances, from about 4 au pre-perihelion to 4 au post-perihelion. The extensive imaging data set allowed us to constrain the dust physical properties, ejection speeds, and production rates as a function of heliocentric distance. The post-perihelion observations, obtained at high cadence in multiple photometric bands (SDSS g, r, i, and luminance filters) and spanning phase angles between approximately 0.7∘ and 30∘, enabled us to determine the dust colour and phase function. The resulting phase curve exhibits a prominent backscattering enhancement, distinct from those derived for Solar system comets, with an opposition surge of 0.1–0.4 mag, a width of 1–3∘, and a linear phase coefficient of 0.02–0.04 mag deg−1, consistent with independent pre-perihelion estimates. A possible interpretation of the imaging data, together with independent photometric measurements, indicates a dust size distribution characterized by a power-law index κ ≈ −3.5, with minimum and maximum particle radii of rmin = 10 μ m and rmax in the interval 1–10 cm. The reported water production rate correlates well with the dust production rate post-perihelion, but fails to do so pre-perihelion, an effect possibly linked to the high CO2/H2O ratio measured before perihelion. The derived maximum dust-loss rate at perihelion is (0.5–1.8)× 104 kg s−1.
Related
- Multi-Wavelength Post-Perihelion Polarimetry of Interstellar Comet 3I/ATLAS
- Post-perihelion Photometric and Spectroscopic Monitoring of the Interstellar Comet 3I/ATLAS
- Very Large Telescope observations of interstellar comet 3I/ATLAS III: High-resolution monitoring of CN and forbidden oxygen emission across the perihelion passage with ESPRESSO
- The σ_s^2- relation in the multi-phase interstellar medium. Exploring the density distribution with the Cloud Factory simulations
- The magnetic field in the multi-phase interstellar medium of NGC 6946
BibTeX
@article{moreno2026dust,
title = {{Dust colour, phase behaviour, and Monte Carlo modelling of interstellar Comet 3I/ATLAS from 4 au Pre- to 4 au post-perihelion}},
author = {Fernando Moreno and Miquel Serra‐Ricart and Javier Licandro and P. J. Gutiérrez and Luisa Maria Lara and Irene Mariblanca-Escalona and M. R. Alarcón},
journal = {Monthly Notices of the Royal Astronomical Society},
year = {2026},
month = jun,
doi = {10.1093/mnras/stag1164},
url = {https://doi.org/10.1093/mnras/stag1164},
note = {CC BY},
}
RIS
TY - JOUR
TI - Dust colour, phase behaviour, and Monte Carlo modelling of interstellar Comet 3I/ATLAS from 4 au Pre- to 4 au post-perihelion
AU - Fernando Moreno
AU - Miquel Serra‐Ricart
AU - Javier Licandro
AU - P. J. Gutiérrez
AU - Luisa Maria Lara
AU - Irene Mariblanca-Escalona
AU - M. R. Alarcón
PY - 2026
DA - 2026/06/18
JO - Monthly Notices of the Royal Astronomical Society
DO - 10.1093/mnras/stag1164
UR - https://doi.org/10.1093/mnras/stag1164
AB - We report multiband photometric imaging observations and Monte Carlo dust tail modelling of the interstellar comet 3I/ATLAS covering a wide range of heliocentric distances, from about 4 au pre-perihelion to 4 au post-perihelion. The extensive imaging data set allowed us to constrain the dust physical properties, ejection speeds, and production rates as a function of heliocentric distance. The post-perihelion observations, obtained at high cadence in multiple photometric bands (SDSS g, r, i, and luminance filters) and spanning phase angles between approximately 0.7^∘ and 30^∘, enabled us to determine the dust colour and phase function. The resulting phase curve exhibits a prominent backscattering enhancement, distinct from those derived for Solar system comets, with an opposition surge of 0.1–0.4 mag, a width of 1–3^∘, and a linear phase coefficient of 0.02–0.04 mag deg^−1, consistent with independent pre-perihelion estimates. A possible interpretation of the imaging data, together with independent photometric measurements, indicates a dust size distribution characterized by a power-law index κ ≈ −3.5, with minimum and maximum particle radii of r_min = 10 μ m and r_max in the interval 1–10 cm. The reported water production rate correlates well with the dust production rate post-perihelion, but fails to do so pre-perihelion, an effect possibly linked to the high CO_2/H_2O ratio measured before perihelion. The derived maximum dust-loss rate at perihelion is (0.5–1.8)× 10^4 kg s^−1.
SN - 0035-8711
SN - 1365-2966
SN - 1365-8711
ER -