FLIERs (fast, low ionization emission regions)

FLIERs (fast, low ionization emission regions) are blobs of material that form a symmetrical pattern in some planetary nebulae, such as the Blinking Nebula and Saturn Nebula. Their origin is not well understood. Some of the observed characteristics of FLIERs suggest that they are like sparks flung outward from the central star within the past thousand years or so. Yet they can also be interpreted as essentially stationary structures, from the surface of which gas is scraped by the outward flow of other gas.