2023/09/22 by Samir Chitnavis, Thomas J. Haworth, Chitnavis, Samir +7
Biochemistry, Genetics and Molecular Biology · Environmental Science · Neuroscience · #Biological Physics (physics.bio-ph) #Earth and Planetary Astrophysics (astro-ph.EP) #FOS: Physical sciences #Microbial Community Ecology and Physiology #Photoreceptor and optogenetics research #Photosynthetic Processes and Mechanisms #Solar and Stellar Astrophysics (astro-ph.SR)
paper · pdf · doi:10.48550/arxiv.2309.12845
openalex publication_date 2023/09/22 · openalex created_date 2023/09/26 · openalex updated_date 2026/07/28
We explore the feasibility and potential characteristics of photosynthetic light-harvesting on exo-planets orbiting in the habitable zone of low mass stars (< 1 M\odot). As stellar temperature, Ts, decreases, the irradiance maximum red-shifts out of the 400 \textrmnm ≤ λ< 750 nm range of wavelengths that can be utilized by oxygenic photosynthesis on Earth. However, limited irradiance in this region does not preclude oxygenic photosynthesis and Earth's plants, algae and cyanobacteria all possess very efficient light-harvesting antennae that facilitate photosynthesis in very low light. Here we construct general models of photosynthetic light-harvesting structures to determine how an oxygenic photosystem would perform in different irradiant spectral fluxes. We illustrate that the process of light-harvesting, capturing energy over a large antenna and concentrating it into a small reaction centre, must overcome a fundamental entropic barrier. We show that a plant-like antenna cannot be adapted to the light from stars of Ts<3400 K, as increasing antenna size offers diminishing returns on light-harvesting. This can be overcome if one introduces a slight enthalpic gradient, to the antenna. Interestingly, this strategy appears to have been adopted by Earth's oxygenic cyanobacteria, and we conclude that bacterial oxygenic photosynthesis is feasible around even the lowest mass M-dwarf stars.