SPHEREx shell around VY Canis Majoris identified as image-processing artifact in new arXiv analysis

The analysis reprocesses early SPHEREx all-sky survey frames centered on the red hypergiant using independent flat-fielding and stray-light models. After applying updated zodiacal-light templates and testing multiple dither combinations, the apparent 10-arcminute shell drops below 3-sigma significance in all tested bands. Residual maps show the feature spatially correlates with the spacecraft's scan-direction artifacts rather than with the star's known asymmetric mass-loss history.

Prior claims relied on a single-pass pipeline that left low-level gradients aligned with the survey's scan pattern. Re-reduction with an independent team pipeline and cross-checks against WISE 12-micron and AKARI far-infrared maps find no corresponding emission at the reported surface brightness. This pattern matches earlier cases where uncorrected 1/f noise in infrared surveys produced false extended structures around bright point sources.

If confirmed, the result tightens requirements for artifact rejection in SPHEREx's public data releases and similar all-sky infrared missions. It also preserves the existing multi-wavelength picture of VY CMa mass loss derived from ALMA, HST, and ground-based adaptive-optics imaging without requiring an additional large-scale shell component.

Independent verification is expected once the next SPHEREx data release includes improved calibration products; observers can test the claim by stacking the same fields with the forthcoming pipeline version.