Obliquity Evolution of the Potentially Habitable Exoplanet Kepler-62f

Area of Science:

• Planetary Science
• Astrophysics
• Climate Dynamics

Background:

• Terrestrial planet axial tilt (obliquity) variations significantly impact climate and habitability.
• Kepler-62f is an exoplanet within its star's habitable zone, making its climate and habitability crucial research areas.

Purpose of the Study:

• To investigate the evolution of Kepler-62f's obliquity over 10-million-year timescales.
• To explore how model assumptions, like planetary masses and the presence of outer bodies, affect obliquity variations.
• To determine the potential impact of obliquity changes on Kepler-62f's climate and habitability.

Main Methods:

• N-body simulations were employed to model the long-term evolution of Kepler-62f's obliquity.
• Simulations explored various scenarios, including different planetary masses and the inclusion of distant gas giants.
• Analysis focused on the interplay between rotational precession frequencies and secular orbital frequencies.

Main Results:

• Obliquity variations were generally limited to under 10°, especially when rotational and secular frequencies aligned.
• Moderate variations (10-20°) were observed under specific conditions of relative nodal longitude, frequency, and phase.
• The presence of outer gas giants on long-period orbits (approx. 1000 days) can induce substantial obliquity variations (up to ~60°) for rapidly rotating Kepler-62f (4-hour period).

Conclusions:

• Obliquity variations on Kepler-62f are sensitive to orbital dynamics and the presence of outer planets.
• Large obliquity swings, driven by giant planets, can significantly alter latitudinal surface flux on million-year timescales.
• These obliquity variations have profound implications for Kepler-62f's climate and potential habitability.