Biosignatures from earth-like planets around M dwarfs (Astrobiology, 2005)

• Antigona Segura
• David Crisp
• James Kasting
• Victoria Meadows

Full Citation:
Segura, A., Kasting, J. F., Meadows, V., Cohen, M., Scalo, J., Crisp, D., Butler, R. A. H., & Tinetti, G. (2005). Biosignatures from Earth-Like Planets Around M Dwarfs. Astrobiology, 5(6), 706–725. https://doi.org/10.1089/ast.2005.5.706

Abstract:
Coupled one-dimensional photochemical-climate calculations have been performed for hypothetical Earth-like planets around M dwarfs. Visible/near-infrared and thermal-infrared synthetic spectra of these planets were generated to determine which biosignature gases might be observed by a future, space-based telescope. Our star sample included two observed active M dwarfs—AD Leo and GJ 643—and three quiescent model stars. The spectral distribution of these stars in the ultraviolet generates a different photochemistry on these planets. As a result, the biogenic gases CH4, N2O, and CH3Cl have substantially longer lifetimes and higher mixing ratios than on Earth, making them potentially observable by space-based telescopes. On the active M-star planets, an ozone layer similar to Earth's was developed that resulted in a spectroscopic signature comparable to the terrestrial one. The simultaneous detection of O2 (or O3) and a reduced gas in a planet's atmosphere has been suggested as strong evidence for life. Planets circling M stars may be good locations to search for such evidence. Key Words: Habitable planets—M dwarfs—Biosignatures—Biomarkers—Terrestrial Planet Finder. Astrobiology 5, 706–725.

URL:
https://www.liebertpub.com/doi/10.1089/ast.2005.5.706

VPL Research Tasks:
Task C: The Habitable Planet