Mass-separation constraints for HWO target systems

Now in its early stages of design, a list of the 164 most promising targets for HWO has been released to the community to carry out precursor science. Massive companions in these systems-stars, brown dwarfs, or giant planets-could preclude the existence of Earth-sized planets in the HZ by impacting their long-term dynamical stability.

Here, we use astrometry from Hipparcos and Gaia Early Data Release 3 (EDR3) to identify stars in the HWO preliminary target list that exhibit astrometric accelerations and determine joint constraints on the expected mass and separation of these companions. We find that 54 HWO targets have significant astrometric accelerations, 37 of which are accounted for by known giant planets and stellar companions. Follow-up efforts are required to clarify the specific nature of the suspected companions around the remaining 17 accelerating stars.