Habitable Zones & Global Climate

Solar System Migration Points to a Renewed Concept: Galactic Habitable Orbits

By Keith Cowing

Status Report

astro-ph.GA

December 5, 2024

Filed under astro-ph.GA, Earth, exoplanet, Galactic bar, Galactic center, Galactic Habitable Orbit, Galactic Habitable Zone, habitability, Sol, solar system, Stellar Cartography, Sun

Solar System Migration Points to a Renewed Concept: Galactic Habitable Orbits — Trajectories of the Sun on the R-t_bk planes for the evolving model. The orange lines show the trajectories of “trapped migrators,” while the green lines depict “untrapped migrators.” Thick lines represent the trajectories of Sun-like particles, while thin lines show orbits similar to those indicated by the thick lines. The background colors with contours indicate (a) the SFR density (Σ_SFR) and (b) lethal GRB event rates (N_GBR), based on the Galactic chemical evolution model (Baba et al. 2023). The black dashed lines indicate the locations of the bar’s CR and OLR radii. — astro-ph.GA

Astrophysical evidence suggests that the Sun was born near 5 kpc from the Galactic center, within the corotation radius of the Galactic bar, around 6-7 kpc.

This presents challenges for outward migration due to the Jacobi energy constraint, preventing stars from easily overcoming the corotation barrier. In this study, we use test particle simulations to explore two possible migration pathways for the Sun: a “trapped” scenario, where the Sun’s orbit was influenced by a slowing Galactic bar, and an “untrapped” scenario driven by dynamic spiral arms.

Our results demonstrate that both mechanisms can explain how the Sun migrated from its birth radius (approximately 5 kpc) to its current orbital radius around 8.5-9 kpc. Furthermore, we investigate the environmental changes experienced by the Sun along these migration pathways, focusing on variations in radiation hazards and comet fluxes, which may have impacted planetary habitability.

These findings highlight the dynamic nature of galactic habitability, emphasizing that the path a star takes within the Milky Way can significantly affect its surrounding environment and the potential for life.

We propose a new concept of “Galactic habitable orbits,” which accounts for evolving galactic structures and their effects on stellar and planetary systems. This work contributes to a deeper understanding of the solar system’s migration and its implications for habitability within the Milky Way.

Junichi Baba (Kagosima U./NAOJ), Takuji Tsujimoto (NAOJ), Takayuki R. Saitoh (Kobe U.)

Comments: accepted for publication in ApJ Letters
Subjects: Astrophysics of Galaxies (astro-ph.GA); Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2412.02963 [astro-ph.GA] (or arXiv:2412.02963v1 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2412.02963
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Related DOI:
https://doi.org/10.3847/2041-8213/ad9260
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Submission history
From: Junichi Baba
[v1] Wed, 4 Dec 2024 02:17:22 UTC (2,145 KB)
https://arxiv.org/abs/2412.02963
Astrobiology

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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