Resolve the Distance Discrepancy for WISEA J155349.96+693355.2

Establish a more accurate distance to the metal-poor T subdwarf WISEA J155349.96+693355.2 in order to resolve the discrepancy between its current astrometric and photometric distance estimates and thereby improve the precision of its inferred Galactic space velocities.

Background

The paper adopts a photometric distance of approximately 39 pc for WISEA J155349.96+693355.2 because the available low signal-to-noise trigonometric parallax implies a shorter distance of roughly 26 pc and produces atmospheric temperatures and radii less consistent with the JWST spectrum and evolutionary models. The adopted distance substantially affects the object's bolometric luminosity, effective temperature, and inferred U, V, and W velocities, which are central to assessing its possible membership in the Gaia-Enceladus Milky Way substructure.

A more precise distance measurement would test whether the photometric-distance interpretation is correct and would reduce the uncertainty in the object's Galactic kinematics. The authors specifically identify continued ground-based J-band astrometric monitoring as a way to improve the trigonometric parallax.