A pinwheel nebula is a class of Wolf–Rayet nebula in the shape of a pinwheel.
Wolf–Rayet nebulae
Some Wolf–Rayet stars are surrounded by pinwheel nebulae. These nebulae are formed from the dust that is spewed out of a binary star system. The stellar winds of the two stars collide and form two dust lanes that spiral outward with the rotation of the system. The first such nebula, located around WR 104, was discovered using the Keck Observatory in 1999. The discovery of a second, WR 98a, established pinwheel nebulae as a distinct class of nebula.
Pinwheel Galaxy M101, better known as the Pinwheel Galaxy, was historically known as the Pinwheel Nebula before Edwin Hubble realized that many spiral shaped nebulae were actually 'island universes' or what we now call galaxies.
References
External links "The Twisted Tale of Wolf-Rayet 104, First of the Pinwheel Nebulae" Some Wolf–Rayet stars in binaries are close enough that we can image a rotating "pinwheel nebula" showing the dust generated by colliding winds in the binary system, from aperture masking interferometry observations. Pinwheel Galaxy from ESA/Hubble