System Architecture and Planetary Obliquity: Implications for Long-term Habitability
Article
Article Title | System Architecture and Planetary Obliquity: Implications for Long-term Habitability |
---|---|
ERA Journal ID | 1048 |
Article Category | Article |
Authors | Vervoort, Pam (Author), Horner, Jonathan (Author), Kane, Stephen R. (Author), Kirtland Turner, Sandra (Author) and Gilmore, James B. (Author) |
Journal Title | The Astronomical Journal |
Journal Citation | 164 (4), pp. 1-15 |
Article Number | 130 |
Number of Pages | 15 |
Year | 2022 |
Publisher | IOP Publishing |
Place of Publication | United States |
ISSN | 0004-6256 |
1538-3881 | |
Digital Object Identifier (DOI) | https://doi.org/10.3847/1538-3881/ac87fd |
Web Address (URL) | https://iopscience.iop.org/article/10.3847/1538-3881/ac87fd |
Abstract | In the search for life beyond our solar system, attention should be focused on those planets that have the potential to maintain habitable conditions over the prolonged periods of time needed for the emergence and expansion of life as we know it. The observable planetary architecture is one of the determinants for long-term habitability as it controls the orbital evolution and ultimately the stellar fluxes received by the planet. With an ensemble of n-body simulations and obliquity models of hypothetical planetary systems, we demonstrate that the amplitude and period of the eccentricity, obliquity, and precession cycles of an Earth-like planet are sensitive to the orbital characteristics of a giant companion planet. A series of transient, ocean-coupled climate simulations show how these characteristics of astronomical cycles are decisive for the evolving surface conditions and long-term fractional habitability relative to the modern Earth. The habitability of Earth-like planets increases with the eccentricity of a Jupiter-like companion, provided that the mean obliquity is sufficiently low to maintain temperate temperatures over large parts of its surface throughout the orbital year. A giant companion closer in results in shorter eccentricity cycles of an Earth-like planet but longer, high-amplitude, obliquity cycles. The period and amplitude of obliquity cycles can be estimated to first order from the orbital pathways calculated by the n-body simulations. In the majority of simulations, the obliquity amplitude relates directly to the orbital inclination whereas the period of the obliquity cycle is a function of the nodal precession and the proximity of the giant companion. |
Keywords | Exoplanet dynamics; Planetary climates; Orbital evolution; Astrobiology; Habitable planets; Astrophysics - Earth and Planetary Astrophysics |
ANZSRC Field of Research 2020 | 510107. Planetary science (excl. solar system and planetary geology) |
510109. Stellar astronomy and planetary systems | |
510101. Astrobiology | |
Byline Affiliations | University of California, United States |
Centre for Astrophysics | |
University of New South Wales | |
Institution of Origin | University of Southern Queensland |
https://research.usq.edu.au/item/q7x11/system-architecture-and-planetary-obliquity-implications-for-long-term-habitability
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