When I was a grad student, right before the launch of Hubble
Space Telescope, I was fascinated by planetary nebulae, the
weird, beautiful halos of gas surrounding dying stars. I still
am! But back then, a big mystery was the transition stage
between the period when a star expands into a red giant and
blows this gas off, and the time the core of the star contracts,
heats up, and lights up that gas by flooding it with intense
ultraviolet light. This stage, called the protoplanetary nebula
stage, only lasts a few thousand years — pretty short on the
galactic timescale. That makes PPNe rare and difficult to
observe… but times have changed. Hubble has been up a while, and
has spotted several of these uncommon beasts, like Minkowski 92:
Isn’t that lovely? The double-lobed shape is a pretty good
indicator that the star in the center isn’t alone; it either has
a companion star or was possibly circled by planets. When the
star expanded into a red giant its rotation slowed, but if there
were a nearby star or some plane