W. F. Huebner

Solar photo rates for planetary atmospheres and atmospheric pollutants

Unattenuated solar photo rate coefficients and excess energies for dissociation, ionization, and dissociative ionization are presented for atomic and molecular species that have been identified or are suspected to exist in the atmospheres of planets, satellites (moons), comets, or as pollutants in the Earth atmosphere. The branching ratios and cross sections with resonances have been tabulated to the greatest detail possible and the rate coefficients and excess energies have been calculated from them on a grid of small wavelength bins for the quiet and the active Sun at 1 AU heliocentric distance.

Origin and early evolution of comet nuclei : workshop honouring Johannes Geiss on the occasion of his 80th birthday

Foreword.- Origins of Cometary Materials.- Origin of Comet Nuclei and Dynamics.- Reservoir for Comet Material: Circumstellar Grains.- Interstellar Reservoirs of Cometary Matter.- Cometary Refractory Grains: Interstellar and Nebular Sources.- Dynamical Origin of Comets and Their Reservoirs.- Reservoirs for Comets: Compositional Differences Based on Infrared Observations.- Thermal and Chemical Evolution of Comet Nuclei and Kuiper Belt Objects.- Loss of the Surface Layers of Comet Nuclei.- Distributed Sources in Comets.- How Well Do Experimental Results on Large Samples of Gas-Laden Amorphous Ice Duplicate Deep Impacts Findings?.- Comet Knudsen Layers.- Morphology-Composition-Isotopes: Recent Results from Observations.- Deep Impact and the Origin and Evolution of Cometary Nuclei.- Assessing the elemental composition of comet 81P/Wild 2 by analyzing dust collected by Stardust.- Composition Measurements of a Comet from the Rosetta Orbiter Spacecraft.- Capabilities of Philae, the Rosetta Lander.- Rapporteur Paper on the Composition of Comets.- The Contributions of Comets to Planets, Atmospheres, and Life: Insights from Cassini-Huygens, Galileo, Giotto, and Inner Planet Missions.

Cometary Materials: Progress Toward Understanding the Composition in the Outer Solar Nebula

A major objective of the workshop was to learn about the chemical composition, physical structure, and thermodynamic conditions of the outer parts of the solar nebula where comets formed. Here we sum up what we have learned from years of research about the molecular constituents of comet comae primarily from in situ measurements of Comet lP/Halley and remote sensing of Comets lP/Halley, Hale-Bopp (C/1995 01), and Hyakutake (C/1996 B2). These three bright comets are presumably captured Oort cloud comets. We summarize the analyses of these data to predict the composition of comet nuclei and project them further to the composition, structure, and thermodynamic conditions in the nebula.