Related papers: Cryptic photosynthesis, Extrasolar planetary oxyge…
Oxygen is a well-studied biosignature. Studying potential abiotic pathways for O2 build-up in exoplanet atmospheres is essential for evaluating whether the detection of O2 would constitute a biosignature detection on other worlds. Previous…
Ocean-atmosphere chemistry on Earth has undergone dramatic evolutionary changes through its long history, with potentially significant ramifications for the emergence and long-term stability of atmospheric biosignatures. Though a great deal…
The strongest remotely detectable signature of life on our planet today is the photosynthetically produced oxygen (O2) in our atmosphere. However, recent studies of Earth's geochemical proxy record suggest that for all but the last ~500…
The emergence of oxygenic photosynthesis created a new niche with dramatic potential to transform energy flow through Earth's biosphere. However, more primitive forms of photosynthesis that fix CO2 into biomass using electrons from reduced…
Standard definitions of habitability assume that life requires the presence of planetary gravity wells to stabilize liquid water and regulate surface temperature. Here the consequences of relaxing this assumption are evaluated. Temperature,…
Previous research has indicated that high amounts of ozone (O3) and oxygen (O2) may be produced abiotically in atmospheres with high concentrations of CO2. The abiotic production of these two gases, which are also characteristic of…
Spectral characterization of Super-Earth atmospheres for planets orbiting in the Habitable Zone of M-dwarf stars is a key focus in exoplanet science. A central challenge is to understand and predict the expected spectral signals of…
The search for life on exoplanets is one of the grand scientific challenges of our time. The strategy to date has been to find (e.g., through transit surveys like Kepler) Earth-like exoplanets in their stars habitable zone, then use…
Remote sensing of the Earth has demonstrated that photosynthesis is traceable as the vegetation red edge (VRE), which is the steep rise in the reflection spectrum of vegetation, and as solar-induced fluorescence. This study examined the…
The near-term capability to characterize terrestrial exoplanet atmospheres may bring us closer to discovering alien life through atmospheric data. However, remotely detectable candidate biosignature gases are subject to false positive…
We show that planets around M-dwarfs with $M_\star \lesssim 0.2 M_\odot$ may not receive enough photons in the photosynthetically active range of $400$-$750$ nm to sustain Earth-like biospheres. As a result of the lower biological…
In the modern search for life elsewhere in the Universe, we are broadly looking for the following: the planets similar to Earth - physical indicators of habitability, and the manifestation of life - the biological signatures. A biosignature…
In order to assess observational evidence for potential atmospheric biosignatures on exoplanets, it will be essential to test whether spectral fingerprints from multiple gases can be explained by abiotic or biotic-only processes. Here, we…
Earth's deciduous plants have a sharp order-of-magnitude increase in leaf reflectance between approximately 700 and 750 nm wavelength. This strong reflectance of Earth's vegetation suggests that surface biosignatures with sharp spectral…
The search for habitable exoplanets in the Universe is actively ongoing in the field of astronomy. The biggest future milestone is to determine whether life exists on such habitable exoplanets. In that context, oxygen in the atmosphere has…
Here we advocate an observational strategy to help prioritize exoplanet observations. It starts with more easily obtained observational data, and ranks exoplanets for more difficult follow-up observations based on the likelihood of avoiding…
How photosynthesis by Precambrian cyanobacteria oxygenated Earth's biosphere remains incompletely understood. Here it is argued that the oxic transition, which took place between approximately 2.3 and 0.5 Gyr ago, required a great…
Photosynthesis is central to Earth's biosphere and a prime candidate for sustaining complex life on habitable exoplanets, yet a thermodynamically consistent treatment of the work potential of stellar radiation at planetary surfaces is still…
We report spectroscopic observations (400 to 800nm, R = approx 100) of Earthshine in June, July and October 2001 from which normalised Earth albedo spectra have been derived. The resulting spectra clearly show the blue colour of the Earth…
Introduction: The search for life on distant exoplanets is expected to rely on atmospheric biosignatures detection, such as oxygen of biological origin. However, it is not demonstrated how much oxygenic photosynthesis, which on Earth…