Lloyd Wallace

Tucson Nighttime Scientific Staff

Areas of Interest

Stellar and Planetary Atmospheres, Radiative Transfer, Minor Constituents in the Earth's Atmosphere, Composition of Sunspots

Recent Research Results

Wallace has found that absorption by very hot water vapor is the dominant source of opacity in the infrared sunspot spectrum. Water vapor forms in the sunspots because of the relatively low temperature but its dominance in matters of heat transfer had not been appreciated. Wallace has also completed detailed studies of bright stars in the infrared spectrum from 2.0 to 2.5 microns. These map more completely than before the development of atomic and molecular absorbers with changes in stellar luminosity and temperature. Notable are the complications revealed - features thought to be due to calcium and sodium alone are actually complex blends with titanium, scandium and vanadium.

Future Research Plans

Wallace will analyze solar spectra gathered by Livingston (NSO) to determine the variation of minor constituents in the earth's atmosphere over the last decade. The technique allows the determination of the total amount in the atmosphere and not just that accessible to analysis at the earth's surface. This allows the tracking of hydrogen chloride and hydrogen fluoride, products of chlorofluorocarbon decomposition, as well as carbon monoxide and dioxide. Wallace also plans to extend his analysis of the sunspot spectrum from the infrared into the visible. This part of the spectrum is very complex and known to be dominated by iron hydride and titanium oxide. He plans to track out the contribution of these two and search the residual for oxides and hydrides of other metals including chromium, vanadium and manganese.


Wallace assists in writing the observing schedule for Kitt Peak, serves on the Library committee, as safety officer on Kitt Peak, and as special advisor on administrative matters.

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NOAO is operated by the Association of U niversities for Research in Astronomy (AURA), Inc. under cooperative agreement with the National Science Foundation
Posted: 06Dec1996