Open science archive // Stellar spectroscopy // Exoplanetary chemistry
A systematic archive documenting the elemental chemistry of exoplanetary systems — measuring what stars are made of, and using that chemistry to understand what their planets are made of too.
Currently indexed: 1 system (55 Cancri / Copernicus) · More systems added as analysis completes
A metal-rich K dwarf 40.9 light years away hosting five planets, including Janssen — a lava-covered super-Earth with CO₂ atmosphere detected by JWST. The C/O ratio of this star remains scientifically contested. We are measuring it.
The calibration anchor for all Codex measurements. Every [X/H] abundance is measured relative to the Sun. Includes Terra, the reference case for all CHNOPS and habitability assessments.
The most solar-like exoplanet host star known. First analyzed in the 2010 thesis that started this project. Now revisited with HARPS at 3× the resolution.
Two planets in the habitable zone. Analyzed in 2010 with poor model fit — M-class stars are hard. The 2026 pipeline will settle whether the anomalous Ni, Co, Si were real or an artifact.
Researcher with a system you'd like analyzed? Collaboration welcome. Contact us with your target and scientific rationale.
HARPS spectra at R~115,000. Each absorption line in the stellar photosphere is a fingerprint of one element at one temperature and pressure.
Gaussian fitting to absorption lines yields equivalent widths — the area of each line — which map directly to elemental column densities.
ATLAS9/Castelli-Kurucz 1D LTE model atmospheres parameterized by Teff, log g, [Fe/H], and microturbulence. The same workhorse used since 1979.
Type A (random) and Type B (systematic) uncertainties documented for every measurement. Error bars are not optional — they are the science.
"This started as a senior astrophysics thesis in 2010 — three star systems, hand-fitted Gaussians, and a question: can you read the chemistry of a star and know what its planets are made of? I spent fifteen years building lasers and consulting on AI. The question never went away."
We're measuring 55 Cancri A now. Get notified when the first Codex entry publishes.