Potential photosynthetic systems in extraterrestrial habitable zones

摘要

A number of photosynthetic systems have evolved on Earth to harvest various portions of the available spectrum from its G2 star. Currently, the number of confirmed extrasolar planets approaches 300, although many are in orbits well outside their habitable zone. This largely results from an observational bias that tends to more easily spot these "hot Jupiters," but increasingly more Earth-like extrasolar planets are detected. The spectral classes of the stars supporting these planets are generally well-identified, permitting some basic assumptions on the inner and outer habitable zone radii. We can also make some assumptions on the spectrum of photon energy available for potential photosynthesis on these planets, allowing for local atmospheric effects. The absorption spectra of terrestrial photosynthetic systems, both naturally evolved, and artificially created, are matched to the anticipated spectra on extrasolar planets. Further consideration is given to the cooler M class stars, whose large number and long life enhance the likelihood of photosynthesis evolving.