Habitable Zones & Global Climate

Resilient Habitability Of Nearby Exoplanet Systems

By Keith Cowing
Press Release
October 18, 2019
Filed under
Resilient Habitability Of Nearby Exoplanet Systems
The planetary systems studied in our simulations. The planet is shown as an orange circle, where the area of the circle is proportional to p Mp/M?. The black lines show the peri- and apo-centre range of the orbit using the reported and ± 1σ values of the eccentricity. If the lower limit is consistent with zero, this is instead represented by a black dot. The green shaded area is the habitable zone calculated according to the formula from Kopparapu et al. (2014) (Equations 1 and 2 of this paper). The systems are split into three categories, from left to right: Group 1 comprises systems with planets on distant orbits and/or with low eccentricity; Group 2 comprises systems with planets on nearby orbits and/or with high eccentricity; and Group 3 comprises systems where the planetary orbits have uncertain eccentricities that could place the systems in either Group 1 or Group 2. The Solar System is shown for scale at the bottom of each panel.

We investigate the possibility of finding Earth-like planets in the habitable zone of 34 nearby FGK-dwarfs, each known to host one giant planet exterior to their habitable zone detected by RV.

First we simulate the dynamics of the planetary systems in their present day configurations and determine the fraction of stable planetary orbits within their habitable zones. Then, we postulate that the eccentricity of the giant planet is a result of an instability in their past during which one or more other planets were ejected from the system.

We simulate these scenarios and investigate whether planets orbiting in the habitable zone survive the instability. Explicitly we determine the fraction of test particles, originally found in the habitable zone, which remain in the habitable zone today. We label this fraction the resilient habitability of a system. We find that for most systems the probability of planets existing [or surviving] on stable orbits in the habitable zone becomes significantly smaller when we include a phase of instability in their history.

We present a list of candidate systems with high resilient habitability for future observations. These are: HD 95872, HD 154345, HD 102843, HD 25015, GJ 328, HD 6718 and HD 150706. The known planets in the last two systems have large observational uncertainties on their eccentricities, which propagate into large uncertainties on their resilient habitability. Further observational constraints of these two eccentriciti

Giorgi Kokaia, Melvyn B. Davies, Alexander J. Mustill
(Submitted on 16 Oct 2019)
Comments: 17 pages, 15 figures, comments welcome
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:1910.07573 [astro-ph.EP] (or arXiv:1910.07573v1 [astro-ph.EP] for this version)
Submission history
From: Giorgi Kokaia
[v1] Wed, 16 Oct 2019 19:03:41 UTC (2,818 KB)

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