Potential Biosignatures in Super-Earth Atmospheres

By H. Rauer, S. Gebauer, P. V. Paris, J. Cabrera, M. Godolt, J. Grenfell, A. Belu, F. Selsis, P. Hedelt, F. Schreier. 2010

139 citations recorded by the source corpus.

Atmospheric temperature and mixing ratio profiles of terrestrial planets vary with the spectral energy flux distribution for different types of M-dwarf stars and the planetary gravity. We investigate the resulting effects on the spectral appearance of molecular absorption bands, that are relevant as indicators for potential planetary habitability during primary and secondary eclipse for transiting terrestrial planets with Earth-like biomass emissions. Atmospheric profiles are computed using a plane-parallel, 1D climate model coupled with a chemistry model. We then calculate simulated spectra using a line-by-line radiative transfer model. We find that emission spectra during secondary eclipse show increasing absorption of methane, water and ozone for planets orbiting quiet M0-M3 dwarfs and the active M-type star AD Leo compared to solar type central stars. However, for planets orbiting very cool and quiet M dwarfs (M4 to M7), increasing temperatures in the mid-atmosphere lead to reduced absorption signals, making the detection of molecules more difficult in such scenarios. Transmission spectra during primary eclipse show strong absorption features of CH4, N2O and H2O for planets orbiting quiet M0-M7 stars and AD Leo. The N2O absorption of an Earth-sized planet orbiting a quiet M7 star can even be as strong as the CO2 signal. However, ozone absorption decreases for planets orbiting such cool central stars due to chemical effects in the atmosphere. To investigate the effect on the spectroscopic detection of absorption bands with potential future satellite missions, we compute signal-to-noise-ratios (SNR) for a James Webb Space Telescope (JWST)-like aperture telescope.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/add64eac636f7f2246758844bb3687c217ad387c

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Citations in the corpus

ABIOTIC OZONE AND OXYGEN IN ATMOSPHERES SIMILAR TO PREBIOTIC EARTH (2014, background): “AD Leonis is a star that has been extensively used in studies of planetary atmospheres (e.g. Domagal-Goldman et al. 2010; Segura et al. 2010; Rauer et al. 2011; von Paris et al. 2013), and GJ 876 is one of the M stars that have UV flux measurements (France al.”
THE ULTRAVIOLET RADIATION ENVIRONMENT AROUND M DWARF EXOPLANET HOST STARS (2012, background): “…the atmospheres of Earth-like planets around M dwarfs have typically been driven to one of two extremes: assuming no UV flux (Segura et al. 2005; Rauer et al. 2011; Kaltenegger et al. 2011) or assuming the spectrum of one of the most active M dwarfs known, AD Leo (Segura et al. 2005; Wordsworth…”
How to Characterize Habitable Worlds and Signs of Life (2017, methodology): “…plane-parallel approach that divides the atmosphere in layers (see, e.g., Kasting et al. 1993; Segura et al. 2005; Tinetti et al. 2006; Selsis et al. 2007; Kaltenegger et al. 2009; Rauer et al. 2011; Kopparapu et al. 2013; Rugheimer et al. 2013; Domagal-Goldman et al. 2014; Ramirez et al. 2014a,b).”
FINDING EXTRATERRESTRIAL LIFE USING GROUND-BASED HIGH-DISPERSION SPECTROSCOPY (2013, methodology): “…than the Earth atmospheric scale height of H = 8 km. Convolved to low spectral resolution, the oxygen transmission signal decreases to 10–20 km—similar to that calculated in earlier studies (Tinetti 2006; Ehrenreich et al. 2006; Kaltenegger & Traub 2009; Rauer et al. 2011; Palle et al. 2011).”
Exoplanet Biosignatures: A Review of Remotely Detectable Signs of Life (2017, background): “Photochemical modeling of terrestrial atmospheres around M dwarf stars has shown that N2O would build up to higher concentrations than on an Earth–Sun analogue given the same source fluxes (Segura et al., 2005; Rauer et al., 2011; Rugheimer et al., 2015a).”