Werner  von Bloh
Limits for photosynthesis in extrasolar planetary systems for Earth-like planets  

Werner von Bloh

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S. Francka, W. von Bloha, C. Bounamaa, M. Steffenb, D. Schönbernerb, and H.-J. Schellnhubera

Adv. Space Res. 28/4, 695-700 (2001)

aPotsdam Institute for Climate Impact Research (PIK), Telegrafenberg, P.O. Box 60 12 03, 14412 Potsdam, Germany.

bAstrophysikalisches Institut Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam, Germany.


We present a general modelling scheme for investigating the possibility of photosynthesis-based life on extrasolar planets. The scheme focuses on the identification of the habitable zone main-sequence-star planetary systems with planets of Earth mass and size. Our definition of habitability is based on the long-term possibility of photosynthetic biomass production as a function of mean planetary surface temperature and atmospheric CO2-content. All the astrophysical, climatological, biogeochemical, and geodynamic key processes involved in the generation of photosynthesis-driven life conditions are taken into account. Implicitly, a co-genetic origin of the central star and the orbiting planet is assumed. The numerical solution of an advanced geodynamic model yields realistic look-up diagrams for determing the limits of photosynthesis in extrasolar planetary systems, assuming minimum CO2 levels set by demand of C4 photosynthesis.

Full text of article incl. figures in PDF-format (180 KByte).


Figure: Width and position of the HZ (shaded) as a function of time for three different central-star masses (M=0.8, 1.0, 1.2 Ms) for an Earth-like planet. Ropt is the optimum position with maximum life span of the photosynthesis-based biosphere.


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