MAKING A NEBULA

The Southern Crab Nebula doesn’t resemble a planetary nebula yet, but it will eventually

CENTRAL BINARY STAR

This consists of a dying red giant, which is shedding its outer layers, and an already burnt-out white dwarf.

JET OF MATERIAL

This seems to have been expelled at higher speed along the axis of the system.

INNER LOBES

A much smaller hourglass, from a more recent outflow event, is embedded in the larger one.

OUTFLOWING MATERIAL

In three dimensions this forms an expanding, twin-lobed ‘hourglass’, but we see it as a twodimensional crablike shape.

EVENTUAL OUTCOME

In due course the red giant will collapse to a white dwarf, surrounded by a more typical planetary nebula.