Search for Past Stellar Encounters and the Origin of 3I/ATLAS
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arXiv
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| Autori principali: | , , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| _version_ | 1866918171985838080 |
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| author | Guo, Yiyang Zhang, Luyao Feng, Fabo Li, Zhao-Yu Pomazan, Anton Yang, Xiaohu |
| author_facet | Guo, Yiyang Zhang, Luyao Feng, Fabo Li, Zhao-Yu Pomazan, Anton Yang, Xiaohu |
| contents | 3I/ATLAS, the third discovered interstellar object, has a heliocentric speed of 58 km/s and exhibits cometary activity. To constrain the origin of 3I/ATLAS and its past dynamical evolution, we propagate the orbits of 3I/ATLAS and nearby stars to search for stellar encounters. Integrating orbits in the Galactic potential and propagating the astrometric and radial-velocity uncertainties of 30 million Gaia stars, we identify 25 encounters with median encounter distances less than 1 pc. However, because the encounter speeds between 3I/ATLAS and each encounter exceed 20 km/s, none is a plausible host under common ejection mechanisms. We infer stellar masses for most stars and quantify the gravitational perturbations exerted by each individual star or each binary system on 3I/ATLAS. The strongest gravitational scattering perturber is a wide M-dwarf binary. Among all past encounters, the binary's barycenter and 3I/ATLAS reach the small encounter distance of 0.242 pc and the encounter speed of 28.39 km/s,1.64 Myr ago. We further demonstrate that the cumulative influence of the stellar encounters on both the speed and direction of 3I/ATLAS is weak. Based on the present kinematics of 3I/ATLAS to assess its origin, we find that a thin-disk origin is strongly favored, because the thin disk both exhibits a velocity distribution closely matching that of 3I/ATLAS and provides the dominant local number density of stars. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_03361 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Search for Past Stellar Encounters and the Origin of 3I/ATLAS Guo, Yiyang Zhang, Luyao Feng, Fabo Li, Zhao-Yu Pomazan, Anton Yang, Xiaohu Solar and Stellar Astrophysics Earth and Planetary Astrophysics Astrophysics of Galaxies 3I/ATLAS, the third discovered interstellar object, has a heliocentric speed of 58 km/s and exhibits cometary activity. To constrain the origin of 3I/ATLAS and its past dynamical evolution, we propagate the orbits of 3I/ATLAS and nearby stars to search for stellar encounters. Integrating orbits in the Galactic potential and propagating the astrometric and radial-velocity uncertainties of 30 million Gaia stars, we identify 25 encounters with median encounter distances less than 1 pc. However, because the encounter speeds between 3I/ATLAS and each encounter exceed 20 km/s, none is a plausible host under common ejection mechanisms. We infer stellar masses for most stars and quantify the gravitational perturbations exerted by each individual star or each binary system on 3I/ATLAS. The strongest gravitational scattering perturber is a wide M-dwarf binary. Among all past encounters, the binary's barycenter and 3I/ATLAS reach the small encounter distance of 0.242 pc and the encounter speed of 28.39 km/s,1.64 Myr ago. We further demonstrate that the cumulative influence of the stellar encounters on both the speed and direction of 3I/ATLAS is weak. Based on the present kinematics of 3I/ATLAS to assess its origin, we find that a thin-disk origin is strongly favored, because the thin disk both exhibits a velocity distribution closely matching that of 3I/ATLAS and provides the dominant local number density of stars. |
| title | Search for Past Stellar Encounters and the Origin of 3I/ATLAS |
| topic | Solar and Stellar Astrophysics Earth and Planetary Astrophysics Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2509.03361 |