Colors of an Earth-like exoplanet: Temporal flux and polarization signals of the Earth

Context. Understanding the total flux and polarization signals of Earth-like planets and their spectral and temporal variability is essential for the future characterization of such exoplanets. Aims. We provide computed total (F) and linearly (Q and U) and circularly (V) polarized fluxes, and the degree of polarization P of sunlight that is...

Investigating cloud cover variability on Earth-like exoplanets using polarimetry

Because clouds scatter and absorb incident radiation, they play crucial roles in the radiative balance, the atmospheric chemistry, climate, and thus the habitability<br/>of a planet. Clouds usually affect the planet’s observables. We investigate here the effect of partial and variable cloud coverage on the light that is reflected by an<br/>Earth...

PyMieDAP: A Python-Fortran tool for computing fluxes and polarization signals of (exo)planets

PYMIEDAP (the Python Mie Doubling-Adding Programme) is a Python-based tool for computing the total linearly and circularly polarized fluxes of incident unpolarized sunlight or starlight that is reflected by solar system planets or moons, respectively, or by exoplanets at a range of wavelengths. The radiative transfer computations are based on...

Circular polarization signals of cloudy (exo)planets

The circular polarization of light that planets reflect is often neglected because it is very small compared to the linear polarization. It could, however, provide information on a planet’s atmosphere and surface, and on the presence of life, because homochiral molecules that are the building blocks of life on Earth are known to reflect...

The O₂ A-Band in the Fluxes and Polarization of Starlight Reflected by Earth-Like Exoplanets

Earth-like, potentially habitable exoplanets are prime targets in the search for extraterrestrial life. Information about their atmospheres and surfaces can be derived by analyzing the light of the parent star reflected by the planet. We investigate the influence of the surface albedo A _s, the optical thickness b _cloud,...

Retrieving the cloud coverage on Earth-like exoplanets using polarimetry

In this work, we analyse linear polarization data of the planet at a distance, obtained with the Extreme Polarimeter (ExPo) on the William Herschel Telescope<br/>on La Palma. These spatially resolved, high-accuracy polarization observations of Venus show faint circular patterns centered on the sub-solar point that are absent in the flux...

Traces of exomoons in flux and polarization signals of starlight reflected by exoplanets

The detection of moons around extrasolar planets is one of the main focuses of current and future observatories. These silent companions contribute to the planets' observed signals but are barely detectable with current methods. Numerous gaseous exoplanets are known to orbit in the habitable zones of stars, and the expected abundance of natural...

Geometric effects on the flux and polarization signals of Jupiter-sized exoplanets

The direct detection of reflected starlight from exoplanets marks the beginning of a new era in the characterization of extrasolar planetary atmospheres. The flux and in particular the linear polarization signals from such planets are sensitive to atmospheric structure and composition, but other effects may also contribute to observed signals....

Investigating circular patterns in linear polarization observations of Venus

In this work, we analyse linear polarization data of the planet at a distance, obtained with the Extreme Polarimeter (ExPo) on the William Herschel Telescope<br/>on La Palma. These spatially resolved, high-accuracy polarization observations of Venus show faint circular patterns centered on the sub-solar point that are absent in the flux...

Using polarimetry to retrieve the cloud coverage of Earth-like exoplanets

Context. Clouds have already been detected in exoplanetary atmospheres. They play crucial roles in a planet’s atmosphere and climate and can also create ambiguities in the determination of atmospheric parameters such as trace gas mixing ratios. Knowledge of cloud properties is required when assessing the habitability of a planet.<br/><br/>Aims....