SPHEREx Spectrophotometry Confirms 13 New Galactic Wolf-Rayet Stars from Gaia Candidates

The preprint reports extraction of SPHEREx spectrophotometry for 30 candidates previously flagged by Gaia XP spectra, confirming 13 WR stars through characteristic emission lines and continuum shapes. Three additional sources match [WC]-type central stars of planetary nebulae while two show He emission without full WR classification. This adds directly to the Milky Way WR census, which remains incomplete especially on the far side of the galactic disk.

Wolf-Rayet stars dominate the production of carbon, nitrogen, and oxygen ejected into the interstellar medium; each new confirmed member tightens models of galactic chemical evolution and the initial-mass function at high masses. The work demonstrates that SPHEREx's low-resolution spectroscopy can separate true WR stars from contaminants when combined with Gaia astrometry, an approach not fully exploited in the original Gaia candidate papers.

The study relies on a small, pre-selected sample rather than a blind search, limiting immediate extrapolation to the full galactic population. Full-sky SPHEREx coverage plus machine-learning classification could scale the method, yet confusion with dusty sources and the mission's sensitivity floor for distant, reddened objects remain unquantified.

Next steps include applying the same criteria to the complete SPHEREx catalog and cross-matching with upcoming infrared surveys to test whether the far-disk WR population has been underestimated by a factor of two.