Red-edge position of habitable exoplanets around M-dwarfs

Abstract One of the possible signs of life on distant habitable exoplanets is the red-edge, which is a rise in the reflectivity of planets between visible and near-infrared (NIR) wavelengths. Previous studies suggested the possibility that the red-edge position for habitable exoplanets around M-dwar...

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Autores principales:	Kenji Takizawa, Jun Minagawa, Motohide Tamura, Nobuhiko Kusakabe, Norio Narita
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2017
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/a2da13c3ea574766a0cbf14f2f142ac0
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spelling	oai:doaj.org-article:a2da13c3ea574766a0cbf14f2f142ac02021-12-02T11:40:13ZRed-edge position of habitable exoplanets around M-dwarfs10.1038/s41598-017-07948-52045-2322https://doaj.org/article/a2da13c3ea574766a0cbf14f2f142ac02017-08-01T00:00:00Zhttps://doi.org/10.1038/s41598-017-07948-5https://doaj.org/toc/2045-2322Abstract One of the possible signs of life on distant habitable exoplanets is the red-edge, which is a rise in the reflectivity of planets between visible and near-infrared (NIR) wavelengths. Previous studies suggested the possibility that the red-edge position for habitable exoplanets around M-dwarfs may be shifted to a longer wavelength than that for Earth. We investigated plausible red-edge position in terms of the light environment during the course of the evolution of phototrophs. We show that phototrophs on M-dwarf habitable exoplanets may use visible light when they first evolve in the ocean and when they first colonize the land. The adaptive evolution of oxygenic photosynthesis may eventually also use NIR radiation, by one of two photochemical reaction centers, with the other center continuing to use visible light. These “two-color” reaction centers can absorb more photons, but they will encounter difficulty in adapting to drastically changing light conditions at the boundary between land and water. NIR photosynthesis can be more productive on land, though its evolution would be preceded by the Earth-type vegetation. Thus, the red-edge position caused by photosynthetic organisms on habitable M-dwarf exoplanets could initially be similar to that on Earth and later move to a longer wavelength.Kenji TakizawaJun MinagawaMotohide TamuraNobuhiko KusakabeNorio NaritaNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 7, Iss 1, Pp 1-11 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Kenji Takizawa Jun Minagawa Motohide Tamura Nobuhiko Kusakabe Norio Narita Red-edge position of habitable exoplanets around M-dwarfs
description	Abstract One of the possible signs of life on distant habitable exoplanets is the red-edge, which is a rise in the reflectivity of planets between visible and near-infrared (NIR) wavelengths. Previous studies suggested the possibility that the red-edge position for habitable exoplanets around M-dwarfs may be shifted to a longer wavelength than that for Earth. We investigated plausible red-edge position in terms of the light environment during the course of the evolution of phototrophs. We show that phototrophs on M-dwarf habitable exoplanets may use visible light when they first evolve in the ocean and when they first colonize the land. The adaptive evolution of oxygenic photosynthesis may eventually also use NIR radiation, by one of two photochemical reaction centers, with the other center continuing to use visible light. These “two-color” reaction centers can absorb more photons, but they will encounter difficulty in adapting to drastically changing light conditions at the boundary between land and water. NIR photosynthesis can be more productive on land, though its evolution would be preceded by the Earth-type vegetation. Thus, the red-edge position caused by photosynthetic organisms on habitable M-dwarf exoplanets could initially be similar to that on Earth and later move to a longer wavelength.
format	article
author	Kenji Takizawa Jun Minagawa Motohide Tamura Nobuhiko Kusakabe Norio Narita
author_facet	Kenji Takizawa Jun Minagawa Motohide Tamura Nobuhiko Kusakabe Norio Narita
author_sort	Kenji Takizawa
title	Red-edge position of habitable exoplanets around M-dwarfs
title_short	Red-edge position of habitable exoplanets around M-dwarfs
title_full	Red-edge position of habitable exoplanets around M-dwarfs
title_fullStr	Red-edge position of habitable exoplanets around M-dwarfs
title_full_unstemmed	Red-edge position of habitable exoplanets around M-dwarfs
title_sort	red-edge position of habitable exoplanets around m-dwarfs
publisher	Nature Portfolio
publishDate	2017
url	https://doaj.org/article/a2da13c3ea574766a0cbf14f2f142ac0
work_keys_str_mv	AT kenjitakizawa rededgepositionofhabitableexoplanetsaroundmdwarfs AT junminagawa rededgepositionofhabitableexoplanetsaroundmdwarfs AT motohidetamura rededgepositionofhabitableexoplanetsaroundmdwarfs AT nobuhikokusakabe rededgepositionofhabitableexoplanetsaroundmdwarfs AT norionarita rededgepositionofhabitableexoplanetsaroundmdwarfs
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Red-edge position of habitable exoplanets around M-dwarfs

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