A twist in the tail: extreme anisotropic mass loss revealed in new colliding-wind wolf-rayet pinwheel
|Date||16 November 2017|
The luminous, massive Wolf-Rayet (WR) stars are thought to be immediate precursors to core-collapse supernovae, and are characterised by powerful high-velocity line-driven winds. Despite the intrinsic rarity of stars in this ephemeral phase, understanding the physics of WR mass loss and evolution has profound implications for galactic astronomy due to their intense winds and radiation fields. A tiny subset of WR stars are late-type Carbon-rich WRs, which are often found in binary systems with the secondary star also supporting a strong wind. Dust formation within such colliding wind binary environments has produced a small handful of exemplar systems in which the wake behind the wind shock is wrapped into a spiral (the so-called ''pinwheel nebulae'').
In this talk I will present the discovery of a new WR pinwheel which displays a host of features from exceptionally strong radio to X-ray emission that identify it as a colliding-wind binary at 1.8 kpc with a windspeed of ~3600 km/s. However, proper motion studies of the 6" spiral plume reveal an expansion of only ~400 km/s; an order of magnitude slower than the derived WR wind. I will show the solution to this severe contradiction lies in a unique double WR binary composition and a new wind-launch mechanism capable of producing an extreme latitude-dependent wind asymmetry.