SPHEREx 0.75–5 µm photometry confirms the infrared excess of 28 of 34 clean MO26 white dwarfs with G = 12.3–16.1; the one excess in 32 clean controls is a blend with a red source 1.8″ away

We used SPHEREx Quick Release 2 spectral images (0.75–5.0 µm, 2025–2026) to test the infrared excesses in the list of Murillo-Ojeda et al. (2026, MO26) of white dwarfs within 100 pc. We did forced PSF photometry at the Gaia DR3 position in each image, and we fitted the Gaia neighbours at the same time. We divided the flux by a Montreal photosphere model. We calibrated the ratio with 20 clean DA control white dwarfs. The controls are 100 random white dwarfs (G < 17) from the Gaia 100 pc catalogue that are not in MO26. This version analyses 145 of the 293 targets with G < 17 (the brightest part). Results for targets without a blend or PSF problem: SPHEREx finds an excess (significance S ≥ 5) in 28 of 34 MO26 white dwarfs (24 of 29 reliable, 4 of 5 tentative). Four are marginal, and two (Ton 214, G 158-45) have no excess. SPHEREx finds an excess in 1 of 32 controls, CBS 204. Spitzer IRAC images resolve a red source 1.8 arcsec from CBS 204. Legacy Surveys images and the WISE position change in 2014–2024 agree with a source that does not move with the white dwarf. Without the blend flag, 10 of 11 blended controls have a false excess. SPHEREx confirms the excess of six MO26 white dwarfs that have no other reference in MO26, for example L 221-49 (S 16.5) and L 454-9 (S 13.0). A blackbody of 700–1900 K fits better than a cool companion for 27 of 29 excess spectra. L 454-9 and EGGR 57 fit better with a companion. We compared the SPHEREx 3.4 µm flux with AllWISE, CatWISE and NEOWISE. A pre-registered rule found a change in 9 of 34 MO26 white dwarfs and in no control. A post-hoc rule adds the extra scatter of excess stars and keeps two: WD J2100+2122 is 40 % fainter than in 2024, after its 2023 outburst, and LAWD 84 is a borderline brightening. WD 0145+234 is 22 % above AllWISE, which agrees with its known brightening. Limitations: the 145 targets are the brightest part of the sample. The SPHEREx pixels are 6.2 arcsec, thus blends limit the method. Some rules are post hoc. We give the code, the photometry and the reproduction steps.

white dwarfs · infrared excess · debris disks · SPHEREx · WISE · NEOWISE · Spitzer IRAC · forced PSF photometry · false positives · source blending · mid-infrared variability · planetary debris · Gaia DR3 · CBS 204 · WD J2100+2122 · LAWD 84 · WD 0145+234 · 100 pc sample