I began my career in 1968 with the calculation of some of the first computer models of the ionized gas in planetary nebulae. These models predicted the observable spectrum for comparison with observed nebulae, allowing the determination of the chemical abundances in these objects. I continued working on planetary nebulae, observing them with the Hubble Space Telescope (we made the first HST observations of the Cat's Eye nebula). I have also worked on the transfer of radiation in the interstellar medium and in the atmospheres of stars, with particular interest in the polarization of radiation from stellar atmospheres. Along with a colleague, in 1968 we made the first calculations of the polarization expected from a rapidly rotating star. This effect was finally observed in 2017.

Research Areas:

Solar, stellar & space plasma physics

Star Formation & The Interstellar Medium

Computation and Simulation