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

TL;DR

This paper presents a catalog of stellar ages for high-priority HWO target stars, emphasizing the current scarcity of precise age measurements and the need for further efforts to improve age constraints before the Habitable Worlds Observatory mission.

Contribution

It compiles published stellar ages using high-precision methods for 659 HWO target stars, highlighting the limited number with precise age estimates and the necessity for ongoing data collection.

Findings

Only 5% of stars have asteroseismic ages.

Approximately 20% have gyrochronal ages.

Median uncertainties are around 9-16%, with systematic uncertainties slightly larger.

Abstract

Precise stellar ages (uncertainties $\lesssim 1$ Gyr, or $\sim 20\%$ at solar age) are required to discern evolutionary trends in atmospheric biosignatures of terrestrial habitable zone exoplanets surveyed by the Habitable Worlds Observatory (HWO) and will aid in constraining planetary interior evolution and target prioritization. We present a catalog of stellar ages for Tier 1 and Tier 2 targets in the HWO Target Stars and Systems (TSS) sub-working group's TSS25 list, compiling published literature ages derived from high-precision methods. The sample comprises 659 stars likely to be observed by HWO, independent of the final mission architecture. This initial catalog focuses on asteroseismology and gyrochronology, which can achieve $\sim 20\%$ precision for the majority of these stars. We find that only $\sim 5\%$ of the sample have asteroseismic ages and $\sim 20\%$ have gyrochronal ages, with just $\sim 2\%$ having constraints from both methods. For stars with multiple published measurements, the median reported statistical uncertainties are slightly smaller than the systematic uncertainties: $\sim 9\%$ versus $\sim 12\%$ for asteroseismology and $\sim 16\%$ versus $\sim 18\%$ for gyrochronology. The scarcity of precise stellar ages in this sample highlights the need for a concerted effort to obtain robust age constraints in advance of HWO; this catalog is intended as a living resource that will be regularly updated in the lead-up to the mission.