Spectropolarimetric signatures of Earth-like extrasolar planets

Abstract

We present results of numerical simulations of the flux (irradiance), F, and the degree of polarization (i.e. the ratio of polarized to total flux), P, of light that is reflected by Earth-like extrasolar planets orbiting solar-type stars, as functions of the wavelength (from 0.3 to 1.0 micron, with 0.001 micron spectral resolution) and as functions of the planetary phase angle. We use different surface coverages for our model planets, including vegetation and a Fresnel reflecting ocean, and clear and cloudy atmospheres. Our adding-doubling radiative transfer algorithm, which fully includes multiple scattering and polarization, handles horizontally homogeneous planets only; we simulate fluxes and polarization of horizontally inhomogeneous planets by weighting results for homogeneous planets. Like the flux, F, the degree of polarization, P, of the reflected starlight is shown to depend strongly on the phase angle, on the composition and structure of the planetary atmosphere, on the reflective properties of the underlying surface, and on the wavelength, in particular in wavelength regions with gaseous absorption bands. The sensitivity of P to a planet's physical properties appears to be different than that of F. Combining flux with polarization observations thus makes for a strong tool for characterizing extrasolar planets. The calculated total and polarized fluxes will be made available through the CDS.

31 pages text, 17 figures, 1 table Submitted to A&A

References in corpus (6)

• Vegetation's Red Edge: A Possible Spectroscopic Biosignature of Extraterrestrial Plants
• Spectral signatures of photosynthesis II: coevolution with other stars and the atmosphere on extrasolar worlds
• Vegetation signature in the observed globally-integrated spectrum of Earth: Modeling the red edge strength using simultaneous cloud data and application for extrasolar planets
• Biomarkers in disk-averaged near-UV to near-IR Earth spectra using Earthshine observations
• Accurate and Approximate Calculations of Raman Scattering in the Atmosphere of Neptune
• Limb polarization of Uranus and Neptune. II Spectropolarimetric observations

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