A recent study published in the Monthly Notices of the Royal Astronomical Society has confirmed what astronomers had suspected for years about the famous Wolf-Rayet 104 “pinwheel star.” Research by Grant Hill, W. M. Keck Observatory Instrument Scientist and astronomer, reveals that WR 104 holds more mystery but is less likely to be a gamma-ray burst (GRB) aimed at Earth.
WR 104 was discovered in 1999 and its remarkable pinwheel structure has been a subject of fascination among astronomers. The star’s unique feature is the result of two massive stars orbiting each other, causing their powerful winds to collide. This collision gives rise to a rotating pinwheel of dust that glows in the infrared.
Initially, one of the two suspected stars was thought to be a massive, evolved star producing a carbon-rich wind, while the second star was believed to be a less evolved but more massive OB star with a hydrogen-rich wind. The collisions between these winds are thought to allow hydrocarbons to form, creating the pinwheel structure.
However, Hill’s research reveals that the stars’ orbits are tilted at least 30 or 40 degrees out of the plane of the sky. This unexpected discovery provides relief for those worried about a nearby GRB pointed directly at Earth but also presents new mysteries to be solved.
“This is such a great example of how the universe surprises us with mysteries we didn’t expect,” Hill said. “WR 104 is not done surprising us yet.” The study highlights the complexities and uncertainties in understanding the physics behind the formation of dust plumes like WR 104.
Source: https://phys.org/news/2025-03-wolf-rayet-pinwheel-star-reveals.html