Not all laboratory astrophysics occurs in labs down here on Earth; sometimes, the lab is in space! A new study has used a space laboratory to confirm a new atomic process — with far-reaching implications.
The Cat’s Eye planetary nebula, as imaged in X-rays and optical light. [X-ray: NASA/CXC/SAO; Optical: NASA/STScI]
Balancing a Plasma
Throughout our universe, cosmic soups of electrons and ions — astrophysical nebulae — fill the spaces surrounding dying stars, hot and compact binaries, and even supermassive black holes. The atoms in these nebulae cycle within a delicate balance: they are ionized (electrons are torn off) by the high-energy photons emitted from the hot nearby sources, and then they recombine (electrons are recaptured), emitting glowing radiation in the process.
After many years of research into atomic processes, we thought that we’d pretty well pinned down the ways in which this photoionization and recombination takes place. This is crucial, since these rates go into models that we use to determine abundances — which, in turn, informs our understanding of stellar evolution, nucleosynthesis, galactic composition and kinematics, and cosmology.
But what if we’re missing something?
A New Process
A diagram of how Rydberg Enhanced Recombination works. Click to enlarge. ...