Boundary conditions for the paleoenvironment: Chemical and physical processes in the pre-solar nebula

The first interstellar hydrocarbon ring, cyclopropenylidene (C3H2) is being studied. Both a survey of galactic sources in several C3H2 transitions and a more detailed study of a subset of these sources are under way. In the latter category is a study of the nearby cold dark cloud TMC-1, which is a potential formation site for solar type stars. A spectra is shown of seven rotational transitions which have been observed at the Five College Radio Astronomy Observatory. Three of these were detected for the first time in any astronomical source: the 3 sub 30 to 2 sub 21 transition at 216 GHz, the 2 sub 21 to 1 sub 10 transition at 122 GHz, and the 1 sub 11 to 0 sub 00 transition at 52 GHz. From the data it is apparent that C3H2 is quite spacially extended in typical interstellar molecular clouds, and that at least in TMC-1 it is one of the most abundant organic molecules

Boundary conditions for the paleoenvironment: Chemical and physical processes in the pre-solar nebula

Two additional hyperfine components of the interstellar radical C3H were detected. In addition, methanol was discovered in interstellar clouds. The abundance of HCCN and various chemical isomers in molecular clouds was investigated

Studies of radiative transfer in planetary atmospheres

Progress is reported in modeling cometary emission in the 18-cm OH transition with specific application and predictions for Comet Halley. Radiative transfer is also being studied in rough and porous media. The kinematics of the cold, dark interstellar cloud Li34N were examined, and CO monitoring of Venus and Mars continues. Analysis of 3.4 mm maps of the lunar surface shows thermal anomalies associated with such surface features as the Crater Copernicus, Mare Imbrium, Mare Nubium, Mare Serenitatis, and Mare Tranquillatis

Studies of radiative transfer in planetary atmospheres

The research emphasis during the period of this report has been on radio observations of comets, related to the International Halley Watch. Observations of the 18 cm lambda-doublet of OH have been carried out monthly. Both of the 1667 and 1665 MHz lines have been repeatedly detected for Comets Halley, Giacobini-Zinner, Thiele, and Hartley-Good. The first astronomical detection of the weak satellite line at 1720 MHz was made for P/Halley. These data promise to supply the highest signal-to-noise-ratio data over an extended period ever obtained for cometary radio observations. Analysis will provide gas production rates as a function of heliocentric distance and allow for detailed comparisons with the OH excitation model involving ultraviolet pumping. In the case of Halley, the lines appear quite symmetric, usually being centered within 0.1 km/s with respect to the nominal nuclear velocity. Line widths have been typically within 10% of 2 km/s. There is thus little evidence for asymmetric emission in the data obtained to date. It seems likely that non-steady-state models of the coma will be required to interpret the data. Evidence for significant departures from the LTE hyperfine ratios was found for Comet Giacobini-Zinner. Smaller, but nonetheless significant, deviations have been found for Comet Halley

Studies of radiative transfer in planetary atmospheres

Schloerb and Claussen continued their analysis of the very high quality data set obtained on the 18 centimeter OH line from the Comet P/Halley with the NRAO 43 meter antenna. The high spectral resolution (0.22 km/sec) and high signal-to-noise of the OH spectra make them ideal for the study of kinematics in the coma. Synthetic profiles were initiated for comparison with the data. A vectorial model was developed using the Monte Carlo techniques originated by Combi and Delsemme. Analysis of the millimeter wavelength observations of HCN emission from P/Halley obtained throughout much of the recent apparition were continued using the University of Massachusetts 14 millimeter-wavelength (FCRAO) antenna. A detailed analysis of the HCN lineshpaes was performed over the last six months. The excitation of HCN in the coma was studied to obtain a detailed match to the observed spectra. The passive millimeter wave radiometer was used to probe the physical and chemical nature of comets from spacecraft. Work was continued on an improved theory of radiative transfer for rough and porous surfaces, such as the regoliths of satellites, asteroids, and comets

Projected free energies for polydisperse phase equilibria

A `polydisperse' system has an infinite number of conserved densities. We give a rational procedure for projecting its infinite-dimensional free energy surface onto a subspace comprising a finite number of linear combinations of densities (`moments'), in which the phase behavior is then found as usual. If the excess free energy of the system depends only on the moments used, exact cloud, shadow and spinodal curves result; two- and multi-phase regions are approximate, but refinable indefinitely by adding extra moments. The approach is computationally robust and gives new geometrical insights into the thermodynamics of polydispersity.Comment: 4 pages, REVTeX, uses multicol.sty and epsf.sty, 1 postscript figure include

Separable approximation to two-body matrix elements

Two-body matrix elements of arbitrary local interactions are written as the sum of separable terms in a way that is well suited for the exchange and pairing channels present in mean-field calculations. The expansion relies on the transformation to center of mass and relative coordinate (in the spirit of Talmi's method) and therefore it is only useful (finite number of expansion terms) for harmonic oscillator single particle states. The converge of the expansion with the number of terms retained is studied for a Gaussian two body interaction. The limit of a contact (delta) force is also considered. Ways to handle the general case are also discussed.Comment: 10 pages, 5 figures (for high resolution versions of some of the figures contact the author