Search

Selective prebiotic conversion of pyrimidine and purine anhydronucleosides into Watson-Crick base-pairing arabino-furanosyl nucleosides in water

Journal Article

Prebiotic nucleotide synthesis is crucial to understanding the origins of life on Earth. There are numerous candidates for life’s first nucleic acid, however, currently no prebiotic method to selectively and concurrently synthesise the canonical Watson...

Sulfidic Anion Concentrations on Early Earth for Surgical Origins-of-Life Chemistry

Journal Article

A key challenge in origin-of-life studies is understanding the environmental conditions on early Earth under which abiogenesis occurred. While some constraints do exist (e.g., zircon evidence for surface liquid water), relatively few constraints exist on...

Photochemical reductive homologation of hydrogen cyanide using sulfite and ferrocyanide

Journal Article

Photoredox cycling during UV irradiation of ferrocyanide in the presence of stoichiometric sulfite is shown to be an extremely effective way to drive the reductive homologation of hydrogen cyanide (HCN) to simple sugars and precursors of hydroxy acids and...

Solvated-electron production by cyanocuprates is compatible with the UV-environment on the Haden-Archaean Earth

Journal Article

UV-driven photoredox processing of cyanocuprates can generate simple sugars necessary for prebiotic synthesis. We investigate the wavelength dependence of this process from 215 to 295 nm and generally observe faster rates at shorter wavelengths. The most...

Three years of Sun-as-a-star radial-velocity observations on the approach to solar minimum

Journal Article

The time-variable velocity fields of solar-type stars limit the precision of radial-velocity determinations of their planets’ masses, obstructing detection of Earth twins. Since 2015 July, we have been monitoring disc-integrated sunlight in daytime using...

Temporal evolution and correlations of optical activity indicators measured in Sun-as-a-star observations

Journal Article

Context. Understanding stellar activity in solar-type stars is crucial for the physics of stellar atmospheres as well as for ongoing exoplanet programmes.

Aims. We aim to test how well we understand stellar activity using our own star, the Sun, as a test...

Growth model interpretation of planet size distribution

Journal Article

The radii and orbital periods of 4,000+ confirmed/candidate exoplanets have been precisely measured by the Kepler mission. The radii show a bimodal distribution, with two peaks corresponding to smaller planets (likely rocky) and larger intermediate-size...

Masses and radii for the three super-Earths orbiting GJ 9827, and implications for the composition of small exoplanets

Journal Article

Super-Earths belong to a class of planet not found in the Solar system, but which appear common in the Galaxy. Given that some super-Earths are rocky, while others retain substantial atmospheres, their study can provide clues as to the formation of both...

Nitrogen Oxide Concentrations in Natural Waters on Early Earth

Journal Article

A key challenge in origins‐of‐life studies is estimating the abundances of species relevant to the chemical pathways proposed to have contributed to the emergence of life on early Earth. Dissolved nitrogen oxide anions ( ), in particular nitrate ( ) and...

HARPS-N Solar RVs Are Dominated by Large, Bright Magnetic Regions

Journal Article

State-of-the-art radial-velocity (RV) exoplanet searches are currently limited by RV signals arising from stellar magnetic activity. We analyze solar observations acquired over a 3 yr period during the decline of Carrington Cycle 24 to test models of RV...

K2-291b: A Rocky Super-Earth in a 2.2 day Orbit

Journal Article

K2-291 is a solar-type star with a radius of R _* = 0.899 ± 0.034 R _⊙ and mass of M_* = 0.934 ± 0.038 M _⊙. From the K2 C13 data, we found one super-Earth planet (R _p  =  R _⊕) transiting this star on a short period orbit (P =  days). We followed this system...

A giant impact as the likely origin of different twins in the Kepler-107 exoplanet system

Journal Article

Measures of exoplanet bulk densities indicate that small exoplanets with radius less than 3 Earth radii (R_⊕) range from low-density sub-Neptunes containing volatile elements¹ to higher-density rocky planets with Earth-like² or iron-rich³ (Mercury-like)...