Exoplanets & Exomoons

Obliquity and Eccentricity Constraints For Terrestrial Exoplanets

By Keith Cowing
Press Release
September 28, 2017
Filed under
Obliquity and Eccentricity Constraints For Terrestrial Exoplanets
Extrasolar planets

Exoplanet discoveries over recent years have shown that terrestrial planets are exceptionally common. Many of these planets are in compact systems that result in complex orbital dynamics.

A key step towards determining the surface conditions of these planets is understanding the latitudinally dependent flux incident at the top of the atmosphere as a function of orbital phase. The two main properties of a planet that influence the time-dependent nature of the flux are the obliquity and orbital eccentricity of the planet.

We derive the criterion for which the flux variation due to obliquity is equivalent to the flux variation due to orbital eccentricity. This equivalence is computed for both the maximum and average flux scenarios, the latter of which includes the effects of the diurnal cycle.

We apply these calculations to four known multi-planet systems (GJ 163, K2-3, Kepler-186, Proxima Centauri), where we constrain the eccentricity of terrestrial planets using orbital dynamics considerations and model the effect of obliquity on incident flux. We discuss the implications of these simulations on climate models for terrestrial planets and outline detectable signatures of planetary obliquity.

Stephen R. Kane, Stephanie M. Torres
(Submitted on 26 Sep 2017)

Comments: 14 pages, 9 figures, 1 table, accepted for publication in AJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:1709.09240 [astro-ph.EP] (or arXiv:1709.09240v1 [astro-ph.EP] for this version)
Submission history
From: Stephen Kane
[v1] Tue, 26 Sep 2017 20:00:08 GMT (628kb)

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) 🖖🏻