Physics Commons^™

The Planetary Nebula A39: An Observational Benchmark For Numerical Modeling Of Photoionized Plasmas, George H. Jacoby, Gary J. Ferland, Kirk T. Korista

Physics and Astronomy Faculty Publications

Galactic nebulae are the main probes for the chemical evolution of the interstellar medium. Yet, recent observations have shown that chemical abundances determined from recombination and collisionally excited emission lines can differ by as much as an order of magnitude in some planetary nebulae (PNs). Many PNs have complex geometries and morphological evidence for interactions from stellar winds, and it is not clear to what extent winds, inhomogeneities, or shocked gas affect the observed spectrum. There currently is no full explanation for this discrepancy, which brings into question whether we understand the physical state of these low-density plasmas at all. …