Constraints on Aquatic Photosynthesis for Terrestrial Planets Around Other Stars

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Oceanic photosynthesis

Aquatic photosynthesis plays a major role in carbon fixation and O2 production on Earth. In this paper, we analyze the prospects for oxygenic photosynthesis in aquatic environments on Earth-analogs around F-, G-, K- and M-type stars.

Our analysis takes into account the spectral type of the host star, attenuation of light by aquatic organisms, and rates of respiration and photosynthesis. We study the compensation depth (ZCO) and the critical depth (ZCR), defined respectively as the locations where the net growth rates and vertically integrated net growth rates of photoautotrophs become zero. Our analysis suggests that ZCO declines by more than an order of magnitude as one moves from the habitable zones around Sun-like stars to late-type M-dwarfs, but ZCR decreases by only a modest amount (∼10%). For M-dwarf exoplanets, we propose that the photosynthetic red edge may constitute a more robust biosignature of aquatic photosynthesis compared to atmospheric O2.

Manasvi Lingam, Abraham Loeb
(Submitted on 9 Dec 2019)
Comments: 6 pages; 3 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:1912.04301 [astro-ph.EP] (or arXiv:1912.04301v1 [astro-ph.EP] for this version)
Submission history
From: Manasvi Lingam
[v1] Mon, 9 Dec 2019 19:00:03 UTC (222 KB)
https://arxiv.org/abs/1912.04301
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