Chemical composition of TRAPPIST-1 measured using high-resolution infrared light

Star system: TRAPPIST-1 | Distance from the Sun: 40.7 light years

TRAPPIST-1 is a small, cool star known for hosting several Earth-sized planets. Because very low-mass stars do not change much over time, they preserve the chemical signature of the cloud of gas and dust from which they formed. Understanding the chemical makeup of such a star provides essential clues about the building materials available to its planets during their formation process.

The chemical composition was determined by analyzing high-resolution, near-infrared light spectra from the star. Researchers focused on the signature of carbon monoxide and its isotopologues, which are versions of molecules containing different forms of atoms, to calculate the star's metallicity and specific chemical ratios.

The analysis reveals that TRAPPIST-1 has a chemical profile largely similar to that of our own Sun. The study measured a carbon-to-oxygen ratio of 0.60, providing a baseline for understanding the materials present in the system's planetary disks. These findings help define the environment in which the TRAPPIST-1 planets were born.

Key findings
- Metallicity of the star is measured at 0.00, indicating a composition similar to the Sun.
- Carbon-to-oxygen ratio of the star is 0.60.
- Carbon isotope ratio (12C/13C) is 154, which is higher than the value measured in the Sun.
- Oxygen isotope ratio (16O/18O) is measured at 490.
- First-ever determination of the stellar carbon-to-oxygen and isotope ratios for TRAPPIST-1.

Scientific study

The Isotopic and Elemental Abundances of Planet-Host Star TRAPPIST-1 (external link)