441 research outputs found
Excitation properties of photopigments and their possible dependence on the host star
Photosynthesis is a plausible pathway for the sustenance of a substantial biosphere on an exoplanet. In fact, it is also anticipated to create distinctive biosignatures detectable by next-generation telescopes. In this work, we explore the excitation features of photopigments that harvest electromagnetic radiation by constructing a simple quantum-mechanical model. Our analysis suggests that the primary Earth-based photopigments for photosynthesis may not function efficiently at wavelengths >1.1 mu m. In the context of (hypothetical) extrasolar photopigments, we calculate the potential number of conjugated pi-electrons (N-*) in the relevant molecules, which can participate in the absorption of photons. By hypothesizing that the absorption maxima of photopigments are close to the peak spectral photon flux of the host star, we utilize the model to estimate N-*. As per our formalism, N-* is modulated by the stellar temperature, and is conceivably higher (lower) for planets orbiting stars cooler (hotter) than the Sun; exoplanets around late-type M-dwarfs might require an N-* twice that of the Earth. We conclude the analysis with a brief exposition of how our model could be empirically tested by future observations
Excitation Properties of Photopigments and Their Possible Dependence on the Host Star
Photosynthesis is a plausible pathway for the sustenance of a substantial
biosphere on an exoplanet. In fact, it is also anticipated to create
distinctive biosignatures detectable by next-generation telescopes. In this
work, we explore the excitation features of photopigments that harvest
electromagnetic radiation by constructing a simple quantum-mechanical model.
Our analysis suggests that the primary Earth-based photopigments for
photosynthesis may not function efficiently at wavelengths m. In
the context of (hypothetical) extrasolar photopigments, we calculate the
potential number of conjugated -electrons () in the relevant
molecules, which can participate in the absorption of photons. By hypothesizing
that the absorption maxima of photopigments are close to the peak spectral
photon flux of the host star, we utilize the model to estimate . As
per our formalism, is modulated by the stellar temperature, and is
conceivably higher (lower) for planets orbiting stars cooler (hotter) than the
sun; exoplanets around late-type M-dwarfs might require an twice that
of the Earth. We conclude the analysis with a brief exposition of how our model
could be empirically tested by future observations.Comment: 9 pages, 2 figures. Published 2021 November 11 in ApJ Letter
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