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My research interests have been varied and involve both theoretical and observational projects. I modeled the ejection of matter from red giants and followed this up with high resolution spectroscopy.
At the time the cosmic background radiation was discovered I investigated the coupling between matter and radiation and showed that the “glue” that kept the gas temperature closely coupled to the radiation temperature was the inverse Compton effect. When the radiation field cools the gas becomes neutral and the gas and radiation temperatures are uncoupled.
When Quasars were discovered I became interested in the continuity between these high luminosity objects and the lower luminosity objects (“Seyfert galaxies”) and with co-workers discovered that they vary in luminosity as do the higher luminosity Quasars.
The quasars themselves provide probes of the intergalactic medium via their extrinsic absorption lines. Surveys of the spectroscopic properties of Quasars led to the serendipitous discovery of the first two examples of gravitational lenses.
Quasars also show intrinsic absorption (“broad absorption line Quasars”) indicating powerful winds with velocities many tens of thousands of km/sec. At the duPont telescope we carried out surveys of Quasar candidates to determine the frequency with which these high velocity winds occur.
As a member of the Hubble Space Telescope high resolution spectrograph team we carried out the first study of the evolution of the intergalactic gas at low redshifts that can only be studied with the HST.
I had overall responsibility for the duPont wide field camera (WFCCD) that I used to study the association between intervening galaxies and the gas producing the absorption in the Quasar spectra.
Since retiring from active astrophysical research I have devoted my time to public outreach in STEM (Science, Technology, Engineering and Math) education. My special focus in that area has been to apply knowledge of the same laws of thermodynamics and radiative transfer in astrophysics to educate the public about climate change brought about by increasing levels of carbon dioxide due to burning of fossil fuels.
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