JWST/MIRI Finds ISM-like Amorphous Silicates in Interstellar Comet 3I/ATLAS
Abstract
We present the first spectroscopic mineralogical analysis of the dust coma of an interstellar object (ISO) from JWST mid-infrared spectroscopy of 3I/ATLAS (3I). 3I exhibits a strong 9- to 11-micron emissivity feature due to Si-O vibrational stretching modes that is commonly seen in asteroids, comets, disks, and the interstellar medium. Characterization of this 10-micron emissivity maximum reveals that 3I's dust composition is dominated by amorphous silicates, and that 3I is unlike Solar System comets, which show significant crystalline silicate dust. Instead, 3I's dust composition is more similar to circumstellar transition disks and the interstellar medium. We suggest 3I may have formed in a distant part of its home system out of interstellar medium-like material, without substantial incorporation of silicates condensed near its host star, unlike the mixing scenarios commonly suggested for the Solar System. Alternatively, 3I's original crystalline silicates may have been amorphized during its Gyr-long journey, although we find this alternative less likely due to 3I's mass loss rate and distinct 10-micron feature as compared to observed Solar System comets.
Related
- JWST/MIRI Observations of Amorphous Silicates in Interstellar Comet 3I/ATLAS
- Characterization of the anisotropic dust activity of interstellar comet 3I/ATLAS
- High-resolution optical spectroscopy reveals the distinctive volatile composition of the interstellar comet 3I/ATLAS
- Origin and evolution of NiI and FeI in the coma of the interstellar comet 3I/ATLAS throughout its trajectory
- Spectral Energy Distribution and Polarimetric Properties of Dust in the Interstellar Comet 3I/ATLAS
BibTeX
@misc{belyakov2026jwstmiri,
title = {{JWST/MIRI Finds ISM-like Amorphous Silicates in Interstellar Comet 3I/ATLAS}},
author = {Matthew Belyakov and Ian Wong and Carey M. Lisse and M. Ryleigh Davis and Bryce T. Bolin and Audrey Martin and Klaus M. Pontoppidan and Geoffrey A. Blake and Christine Chen and Michael E. Brown},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.27535},
eprint = {2606.27535},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.27535},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - JWST/MIRI Finds ISM-like Amorphous Silicates in Interstellar Comet 3I/ATLAS
AU - Matthew Belyakov
AU - Ian Wong
AU - Carey M. Lisse
AU - M. Ryleigh Davis
AU - Bryce T. Bolin
AU - Audrey Martin
AU - Klaus M. Pontoppidan
AU - Geoffrey A. Blake
AU - Christine Chen
AU - Michael E. Brown
PY - 2026
DA - 2026/09/16
PB - arXiv
DO - 10.48550/arxiv.2606.27535
UR - https://arxiv.org/abs/2606.27535
AB - We present the first spectroscopic mineralogical analysis of the dust coma of an interstellar object (ISO) from JWST mid-infrared spectroscopy of 3I/ATLAS (3I). 3I exhibits a strong 9- to 11-micron emissivity feature due to Si-O vibrational stretching modes that is commonly seen in asteroids, comets, disks, and the interstellar medium. Characterization of this 10-micron emissivity maximum reveals that 3I's dust composition is dominated by amorphous silicates, and that 3I is unlike Solar System comets, which show significant crystalline silicate dust. Instead, 3I's dust composition is more similar to circumstellar transition disks and the interstellar medium. We suggest 3I may have formed in a distant part of its home system out of interstellar medium-like material, without substantial incorporation of silicates condensed near its host star, unlike the mixing scenarios commonly suggested for the Solar System. Alternatively, 3I's original crystalline silicates may have been amorphized during its Gyr-long journey, although we find this alternative less likely due to 3I's mass loss rate and distinct 10-micron feature as compared to observed Solar System comets.
ER -