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Nucleus and Postperihelion Activity of Interstellar Object 3I/ATLAS Observed by Hubble Space Telescope
Man-To Hui, David Jewitt, Max J. Mutchler et al., 2026. arXiv.
Extracts the nucleus from Hubble images of December 2025 and January 2026: an effective radius of 1.3 ± 0.2 km for a comet-like albedo, consistent with the size implied by the non-gravitational acceleration; an axis ratio of at least 2:1 if the brightness variation is rotational; faster fading after perihelion than brightening before, which is not unusual for comets.
What it's used for here
The measured size of 3I, which rules out the earlier claim of a nucleus above 5 km.
Our copy
Research copy, for editors and curators. The work is arXiv-nonexclusive, so readers are sent to it. We keep this copy so the citation can be checked if the page changes or goes.
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Cited by on this site 2 records
EVD
1I/'Oumuamua
MYSThe mystery article
Cite it
Hui, M. T., Jewitt, D., Mutchler, M. J., Agarwal, J., & Kim, Y. (2026). Nucleus and Postperihelion Activity of Interstellar Object 3I/ATLAS Observed by Hubble Space Telescope. arXiv. https://doi.org/10.3847/2041-8213/ae471c
@article{hui2026nucleus,
author = {Hui, Man-To and Jewitt, David and Mutchler, Max J. and Agarwal, Jessica and Kim, Yoonyoung},
title = {Nucleus and Postperihelion Activity of Interstellar Object 3I/ATLAS Observed by Hubble Space Telescope},
journal = {arXiv},
year = {2026},
doi = {10.3847/2041-8213/ae471c},
url = {https://arxiv.org/abs/2601.21569}
}TY - GEN TI - Nucleus and Postperihelion Activity of Interstellar Object 3I/ATLAS Observed by Hubble Space Telescope AU - Hui, Man-To AU - Jewitt, David AU - Mutchler, Max J. AU - Agarwal, Jessica AU - Kim, Yoonyoung PY - 2026 JO - arXiv DO - 10.3847/2041-8213/ae471c UR - https://arxiv.org/abs/2601.21569 ER -
Hui, Man-To et al.. “Nucleus and Postperihelion Activity of Interstellar Object 3I/ATLAS Observed by Hubble Space Telescope.” arXiv (2026). https://doi.org/10.3847/2041-8213/ae471c.