HAges Catalog: Stellar Ages for High-Priority HWO Target Stars

Researchers from Arizona State University have released the HAges Catalog, a specialized dataset designed to provide precise stellar ages for stars targeted by the Habitable Worlds Observatory (HWO). The catalog serves as a critical technical foundation for the future mission, as determining the age of a star is essential for identifying evolutionary trends in the atmospheric biosignatures of terrestrial exoplanets located within habitable zones.

The research, submitted on May 12, 2026, by Austin T. Ware, Katelyn Ruppert, and Patrick A. Young of the School of Earth and Space Exploration, addresses a significant data gap in the preparation for the HWO mission. Precise age constraints are necessary not only for understanding biosignatures but also for prioritizing targets and constraining the evolution of planetary interiors.

The HAges Catalog compiles published literature ages for 659 stars. These stars are identified as Tier 1 and Tier 2 targets from the TSS25 list, which was developed by the Habitable Worlds Observatory Target Stars and Systems (TSS) sub-working group.

To be useful for the mission’s goals, the researchers note that stellar age uncertainties must be less than or equal to 1 gigayear, which represents approximately 20 percent precision at the age of the sun.

The catalog focuses on two primary high-precision dating methods: asteroseismology and gyrochronology. Asteroseismology involves studying the internal oscillations of stars to determine their structure and age, while gyrochronology estimates age based on the star’s rotation period.

The findings revealed a stark scarcity of precise data for the target stars. According to the study, only approximately 5 percent of the 659 stars in the sample have asteroseismic ages, and approximately 20 percent have gyrochronal ages. Only about 2 percent of the targets have age constraints derived from both methods.

The researchers also analyzed the precision of existing measurements. For stars with multiple published measurements, the median reported statistical uncertainties were slightly lower than the systematic uncertainties. Specifically, asteroseismology showed statistical uncertainties of approximately 9 percent compared to systematic uncertainties of approximately 12 percent. Gyrochronology showed statistical uncertainties of approximately 16 percent compared to systematic uncertainties of approximately 18 percent.

The development of the catalog relied on technical tools including the NumPy and astropy software libraries.

The authors state that the current lack of precise stellar ages highlights the necessity for a concerted effort to obtain robust age constraints in advance of HWO. To address this, the HAges Catalog is designed as a living resource that will be updated regularly as new data becomes available leading up to the mission.

By centralizing these measurements, the catalog allows the scientific community to better understand which targets are most viable for the HWO mission architecture, regardless of the final technical specifications of the observatory.