Sapaki

Sapaki, cataloged as WR 67a, is a highly luminous O-type main-sequence star located in the southern constellation of Circinus. Positioned deep within the Milky Way plane, it is heavily obscured by cosmic dust, making it invisible to the naked eye with an apparent visual magnitude of approximately 14.9. Initially classified as a hot Wolf–Rayet star of the subtype WN6h, high-resolution spectroscopic observations later refined its classification to an extremely hot, massive main-sequence star of spectral type O3If*. Stars of this class are among the most massive, hottest, and most luminous conventional stars known in the universe. Sapaki occupies a highly unusual astronomical environment. It is located near the center of a giant interstellar emission cavity visible at 8.0 \(\mu \)m. Massive O-type stars typically form within dense stellar clusters; however, Sapaki appears completely isolated within its cavity. Astrometric data from the Gaia spacecraft is actively used by astronomers to study its proper motion to determine whether it formed in situ or if it is a runaway star ejected from a nearby star cluster.