Surface flux patterns on planets in circumbinary systems and potential for photosynthesis

Duncan H. Forgan (Lead / Corresponding author), Alexander Mead, Charles S. Cockell, John A. Raven

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Recently, the Kepler Space Telescope has detected several planets in orbit around a close binary star system. These so-called circumbinary planets will experience non-trivial spatial and temporal distributions of radiative flux on their surfaces, with features not seen in their single-star orbiting counterparts. Earth-like circumbinary planets inhabited by photosynthetic organisms will be forced to adapt to these unusual flux patterns. We map the flux received by putative Earth-like planets (as a function of surface latitude/longitude and time) orbiting the binary star systems Kepler-16 and Kepler-47, two star systems which already boast circumbinary exoplanet detections. The longitudinal and latitudinal distribution of flux is sensitive to the centre-of-mass motion of the binary, and the relative orbital phases of the binary and planet. Total eclipses of the secondary by the primary, as well as partial eclipses of the primary by the secondary add an extra forcing term to the system. We also find that the patterns of darkness on the surface are equally unique. Beyond the planet's polar circles, the surface spends a significantly longer time in darkness than latitudes around the equator, due to the stars’ motions delaying the first sunrise of spring (or hastening the last sunset of autumn). In the case of Kepler-47, we also find a weak longitudinal dependence for darkness, but this effect tends to average out if considered over many orbits. In the light of these flux and darkness patterns, we consider and discuss the prospects and challenges for photosynthetic organisms, using terrestrial analogues as a guide.

Original languageEnglish
Pages (from-to)465-478
Number of pages14
JournalInternational Journal of Astrobiology
Volume14
Issue number3
Early online date28 Nov 2014
DOIs
Publication statusPublished - Jul 2015

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photosynthesis
surface flux
darkness
planets
planet
orbits
autotrophs
binary stars
eclipses
organisms
stars
planet detection
longitude
sunrise
sunset
temporal distribution
autumn
equators
center of mass
spatial distribution

Keywords

  • circumbinary
  • darkness
  • habitability
  • photosynthesis

Cite this

Forgan, Duncan H. ; Mead, Alexander ; Cockell, Charles S. ; Raven, John A. / Surface flux patterns on planets in circumbinary systems and potential for photosynthesis. In: International Journal of Astrobiology. 2015 ; Vol. 14, No. 3. pp. 465-478.
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Surface flux patterns on planets in circumbinary systems and potential for photosynthesis. / Forgan, Duncan H. (Lead / Corresponding author); Mead, Alexander; Cockell, Charles S.; Raven, John A.

In: International Journal of Astrobiology, Vol. 14, No. 3, 07.2015, p. 465-478.

Research output: Contribution to journalArticle

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