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Quarles B, Barnes JW, Lissauer JJ, Chambers J. Obliquity Evolution of the Potentially Habitable Exoplanet Kepler-62f. ASTROBIOLOGY 2020; 20:73-90. [PMID: 31613645 DOI: 10.1089/ast.2018.1932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Variations in the axial tilt, or obliquity, of terrestrial planets can affect their climates and therefore their habitability. Kepler-62f is a 1.4 R⊕ planet orbiting within the habitable zone of its K2 dwarf host star. We perform N-body simulations that monitor the evolution of obliquity of Kepler-62f for 10-million-year timescales to explore the effects on model assumptions, such as the masses of the Kepler-62 planets and the possibility of outer bodies. Significant obliquity variation occurs when the rotational precession frequency overlaps with one or more of the secular orbital frequencies, but most variations are limited to ≲10°. Moderate variations (∼10-20°) can occur over a broader range of initial obliquities when the relative nodal longitude (ΔΩ) overlaps with the frequency and phase of a given secular mode. However, we find that adding outer gas giants on long-period orbits (∼1000 days) can produce large (∼60°) variations in obliquity if Kepler-62f has a very rapid (4 h) rotation period. The possibility of giant planets on long-period orbits impacts the climate and habitability of Kepler-62f through variations in the latitudinal surface flux, where large variations can occur on million year timescales.
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Affiliation(s)
- Billy Quarles
- Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, Atlanta, Georgia
| | - Jason W Barnes
- Department of Physics, University of Idaho, Moscow, Idaho
| | - Jack J Lissauer
- NASA Ames Research Center, Astrobiology and Space Science Division MS 245-3, Moffett Field, California
| | - John Chambers
- Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington, District of Columbia
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Way MJ, Del Genio AD, Kiang NY, Sohl LE, Grinspoon DH, Aleinov I, Kelley M, Clune T. Was Venus the First Habitable World of our Solar System? GEOPHYSICAL RESEARCH LETTERS 2016; 43:8376-8383. [PMID: 28408771 PMCID: PMC5385710 DOI: 10.1002/2016gl069790] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Present-day Venus is an inhospitable place with surface temperatures approaching 750K and an atmosphere 90 times as thick as Earth's. Billions of years ago the picture may have been very different. We have created a suite of 3-D climate simulations using topographic data from the Magellan mission, solar spectral irradiance estimates for 2.9 and 0.715 Gya, present-day Venus orbital parameters, an ocean volume consistent with current theory, and an atmospheric composition estimated for early Venus. Using these parameters we find that such a world could have had moderate temperatures if Venus had a rotation period slower than ~16 Earth days, despite an incident solar flux 46-70% higher than Earth receives. At its current rotation period, Venus's climate could have remained habitable until at least 715 million years ago. These results demonstrate the role rotation and topography play in understanding the climatic history of Venus-like exoplanets discovered in the present epoch.
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Affiliation(s)
- M J Way
- NASA Goddard Institute for Space Studies, 2880 Broadway, New York, New York, USA
- Department of Astronomy & Space Physics, Uppsala University, Uppsala, Sweden
| | - Anthony D Del Genio
- NASA Goddard Institute for Space Studies, 2880 Broadway, New York, New York, USA
| | - Nancy Y Kiang
- NASA Goddard Institute for Space Studies, 2880 Broadway, New York, New York, USA
| | - Linda E Sohl
- NASA Goddard Institute for Space Studies, 2880 Broadway, New York, New York, USA
- Center for Climate Systems Research, Columbia University, New York, New York, USA
| | | | - Igor Aleinov
- NASA Goddard Institute for Space Studies, 2880 Broadway, New York, New York, USA
- Center for Climate Systems Research, Columbia University, New York, New York, USA
| | - Maxwell Kelley
- NASA Goddard Institute for Space Studies, 2880 Broadway, New York, New York, USA
| | - Thomas Clune
- Global Modeling and Assimilation Office, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
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