Several calculations of the Asymptotic Giant Branch star evolution have been performed with the aim of explaining the synthesis of interstellar 26Al in these stars. The agreement of theoretically calculated mass of interstellar 26Al and observations is rather satisfactory, the best for the abrupt tenfold jump in the mass-loss rate for the stars reaching the luminosity log(L/L⊙) ⋍ 4.0.

It is shown that radiative pressure in vibronic transitions of molecules may play an important role in origin of mass outflow of cold giants and supergiants.

The key problem in cometary chemistry is to observe abundances of species in the coma and to reassemble those species into the species that are present in the nucleus. The limitations are primarily due to poorly constrained models and the lack of uniqueness in reassembling parent species from the fragments when not all of the fragments are observable. These problems will be illustrated with several examples.

The origin of carbon and water on the terrestrial planets is not trivial, because their presence seems to be excluded by the high temperatures requested by the accretion disk models (Morfill 1988) as well as by Lewis' (1973) adiabat that can explain the different densities of the planets. These high temperatures imply that all dust was outgassed and dehydrated and most carbon stored in CO, that is in the gas phase, before the separation of dust from gas, that occurred by dust sedimentation to the mid-plane of the accretion disk. Thermochemical equilibrium was easily reached, since chemical kinetics (Lewis & Prinn 1980) had time constants shorter than the time needed to agglomerate the first planetesimals (Weidenschilling 1988).

The 3 micron spectrum of the galactic center source IRS 7 is compared to a spectrum obtained on the deuterium-rich organic polymer extracted from the Orgueil carbonaceous meteorite. The almost perfect match between the two spectra in the 3.4 μm region suggests that the chemical composition of the interstellar organic matter resembles that of the meteoritic macromolecule.

Chemical abundances in the solar corona or solar wind compared to those in the photosphere differentiate according to first ionization potential (FIP). We suggest that the effect is the result of diamagnetic diffusion pumps operating in the presence of gravitation and diverging magnetic structures. We then comment briefly on implications concerning abundances in the solar system and chemically peculiar stars.

Which molecular species are firmly identified as cometary species and which are also interstellar? How may excitation effects bias the data interpretation?

The techniques of low temperature spectroscopy are applied here to analyze infrared observational data of Io in the 2.0-5.0 μm range. The presence of solid H2S and traces of H2O in the SO2-dominant surface ices are derived from this analysis and it is suggested that CO2 clusters may as well be present near the surface of Io.

Clathrate Hydrates can be formed under high vacuum conditions by annealing vapor-deposited amorphous ices of the appropriate composition. When astrophysically significant H2O:CH3OH ices are deposited and annealed, Type II Clathrate Hydrates are formed which can hold up to 6 mole % large guest molecules such as methanol and 12 mole % small guest molecules such as CO2 and CO. The solid state transformation of amorphous mixed molecular ice into crystalline clathrate hydrate and its sublimation at higher temperatures may serve to explain heretofore anomalous mechanical and gas release properties observed in cometary ices and laboratory ice analog experiments.

We present observations of cometary parent molecules at the IRAM radio telescope which led to the first detections of H2S and CH3OH in comets, and confirmed the presence of H2CO and HCN. Production rates and abundances relative to H2O are given.

A useful method for extracting cometary signals is demonstrated using VLA observations of Comet Brorsen-Metcalf (1989o).

Emission fluxes of CN, C2 and C3 carbon- bearing molecular species observed in the coma of comets Bennett (1969i ≡ 1970II), West (1975n = 1976VI), P/Halley (1982i), Hartley-Good (1985l) and Bradfield (1987s) are analysed in the framework of Haser model. CN, C2 and C3 production rates are determined using recently derived fluorescence efficiencies. The dependence of CN, C2 and C3 production rates on the heliocentric distance and the possible correlations among these radicals is studied and briefly discussed.

Emission features of C2, C3, CN, and dust in Comets Thiele (1985m), Hartley-Good (1985l), and Giacobini-Zinner (1984e) have been analyzed and their mass loss rates of about 0.5, 1.1, and 0.8 Mg s−1 have been determined.

We apply our fluid dynamic model with chemical kinetics of dusty comet comae to P/Tempel 2. A brief summary of results concerning gas/dust dynamics and chemistry is given.

The growing body of data on solar system objects and interstellar space provides us with new tests of the connection between the two. We emphasize here the role played by the study of comets through the properties of the dust, the chemical composition of volatiles and the elemental abundances. These data inform us on cometary matter formation, and hence on conditions in the protosolar nebula. Under the adopted scenario of formation in a cold environment, with little further processing, cometary abundances are even new constraints to interstellar (gas and solid phase) abundances. Several points specific to the chemical modelling of the collapsing cloud and of the protosolar nebula are listed.

Recent determinations of H2S and other sulfur compounds abundances in comets and in Orion KL bring new tests of the origin of cometary matter.

The energy of the SiH vibrational fundamental has been shown be extremely sensitive to the oxidation state of the silicon to which the hydrogen is bound, ranging from 4.4 microns in highly oxidized silicate grains to 4.74 microns in silicon carbide (Moore, Tanabé and Nuth, Ap. J. (Lett.) 373, L31-L34, 1991). Yin, Ghose and Adler (Appl. Spectrosc. 26, 355-7, 1972) have shown that the process of ion-sputtering a metal oxide results in chemical reduction, due to the high sputtering yield and volatility of oxygen relative to the metal. These authors have shown that solar wind ion-sputtering of lunar soils could provide an explanation for the observed solar wind darkening of the lunar surface. We hypothesize that a similar ion-reduction process could occur on asteroidal surfaces exposed to the solar wind. A second consequence of solar wind exposure would be the implantation of hydrogen ions into the asteroidal surface. Stein (J. Elec. Mat. 4, 159-174, 1975) has shown that hydrogen-ions implanted into silicon exhibit infrared absorptions between 4.5 and 5.5 microns: similar features should result from the ion-implantation of hydrogen ions into partially reduced silicate minerals and glasses. The position of such features would be indicative of the local chemical environment of the silicon atom to which the hydrogen was bound.

The quantity of scientific work in the area of astrochemistry is now enormous, and this meeting - in attempting to cover most of the aspects of our subject - has had problems in coping with it due to difficulty of reviewing very active, broad areas in a limited time. At this meeting we have had almost 40 hours of formal and informal discussion, and about 45 oral presentations at which I estimate that about 1500 transparencies and slides have been projected for our enlightenment. About 100 posters have been presented in three sessions. The posters were uniformly of a high standard and generated a great deal of interest and discussion. I think the prominence given in the programme to the posters has been particularly successful. The range of activity, and the enthusiasm with which it is pursued, demonstrate that astrochemistry is in a vigorous state. It has its own intrinsic interest, and in its present maturity is now making substantial contributions to understanding in astronomy.

A wide variety of molecules have been observed in the interstellar clouds. They are believed to be formed by reaction networks which begin with ionization by cosmic-rays. Cosmic-rays are also an important heating mechanism for many astrophysical regions. In this paper I shall review the methods used to infer the cosmic-ray ionization rate and the values which have been measured.

The high latitude molecular clouds are discussed in the context of the formation of very low mass condensations: protojupiters. The ability to identify such objects is intimately tied to the resolution of the current debate concerning the density of the condensations inferred from observations of high density tracers. At the heart of the debate is whether inclusion of electron excitation plays an important role in the determination of column densities. A brief review of molecular abundances shows that with the possible exception of H2CO, the molecular abundances in the high latitude molecular clouds are not abnormal.