Left: Minimum detectable radius of a habitable-zone exoplanet (T_eq = 287 K) for each WD in our sample. This figure demonstrates that the size of HZ planet that can be detected depends primarily on the distance to the system. The small amount of scatter in this dependence is due to variations in the temperature and radius of the WD – a fit for hot (T_eff = 20 000 K) WDs (top dotted line) and cold (T_eff = 6000 K) WDs (bottom dotted line) is shown here, and an equation for this fit is given in the text. The magnitude of the WD is not a driving factor when determining the minimum detectable planet radius Right: Minimum detectable exoplanets of a given temperature-radius around WDs at four different distances (2.7–13 pc). Earth-analogs can be detected around WDs within 6 pc of Earth and hot, rocky planets with tenuous atmospheres (Mercury-analogues) within 10 pc. Habitable-zone exoplanets orbiting WDs are detectable via IR excess out to 8–10 pc (e.g. Kepler-62e). Jupiters and Saturns are detectable with MRS out to 10–20 pc, but can more efficiently be detected with 21 μm MIRI imaging. For both plots, we determine detectability based on the amount of IR excess measured from the exoplanet with 10 h of observation in the JWST MIRI/MRS sub-band C channels (see Section 5.1.4).