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Recycling and loss rates for a typical interstellar cloud are considered, giving attention to disagreements concerning some of the production rates. It is pointed out that the formation rate of CH(+) via vibrationally excited hydrogen molecules exceeds in many situations rates of other processes. In low density clouds comparable amounts of CH and CH(+) are produced when the fast dissociative recombination rate is used. more...

Reexamination of a model originally suggested by Bates and Spitzer (1951) for interstellar molecule production by evaporation of grain mantles. It is shown that allowance for reactions involving CH(+), formerly ignored, remove the difficulties experienced by Bates and Spitzer. The essential features of CH and CH(+) observations in the directions of certain stars can be understood on the basis of this model. more...

Report of a new upper limit on interstellar boron in the direction of zeta Oph, obtained by making 25 scans across the B II resonance line at 1362.461 A with the Copernicus satellite. A B/H of about 7.6 times 10 to the negative 11th power or less was found, implying that boron in the interstellar gas is depleted by a factor of about 60 relative to boron in carbonaceous chondrites. These results are related to theories of the formation of grains, and the flux of cosmic rays. more...

Gum Nebula conceived as hydrogen gas mass ionized by UV radiation from supernova explosion related to Vela X remnant, discussing fossil Stroemgren sphere model

When a supernova occurs, there is a release of sufficient energy to ionize a large amount of the surrounding material. The Gum nebula is an example of this process.

Papers were presented in conference sessions on the Gum nebula, the Vela X remnant, the hot stars gamma Velorum and zeta Puppis, the B associations in the Vela-Puppis complex, and pulsars. Ground-based optical and radio astronomy; rocket and satellite observations in the radio, visible, ultraviolet, and X-ray regions; and theoretical problems in the physical state of the interstellar medium, stellar evolution, and runaway star dynamics were considered. more...

Gum Nebula size, density and electron temperature data from RAE-1 and OGO-5 satellites and ground based telescopes observations, correlating with Vela X supernova outburst

Equivalent widths of CO lines in interstellar absorption spectrum of zeta Ophiuchi

Gum Nebula-fossil Stromgren sphere of Vela X supernova, deriving ionization model from interstellar measurements

Interstellar hydrogen ion production and destruction by electron recombination or photodissociation

Stellar spectrophotometry by rocket-borne equipment, describing instrumentation, rocket assembly, calibration and spectra obtained

UV interstellar extinction from comparison of epsilon and zeta Persei, noting graphite features

Planetary nebula formation mechanism based on slow mass loss due to radiation pressure on grains

Positively charged diatomic hydrogen molecules interstellar extinction and photodissociation cross section in terms of formation mechanisms

Interstellar extinction in UV from zeta and epsilon Persei spectra obtained with scanner attached to telescope mounted in pointed Aerobee rocket

Spinning rockets UV spectrophotometry of early type stars, discussing instrumentation, calibration, data recording and stellar spectra

Ultraviolet spectra by rocket observations of Zeta Puppis and Gamma Velorum

Interstellar SHF radio emission from hydroxyl molecules, discussing maser emission excitation mechanism

Localized interstellar molecular hydrogen formation in situations relevant to observations of OB clusters and associations with little H alpha emission

Graphite grain formation in stellar atmosphere, analyzing Hoyle-Wickramasinghe condensation mechanism and supersaturation based on nucleation theory

Interstellar neutral hydrogen column densities from Lyman alpha measurements noting discrepancies in Orion direction

Photodissociation of hydrogen molecules in H I regions of interstellar medium, evaluating lifetime and density

Far UV extinction curve and wavelength dependence of interstellar polarization by graphite grains

Interstellar molecule formation as result of chemical exchange reactions between atoms of interstellar gas and atoms chemically bound to interstellar grains

Graphite grain formation in cool stars examined on basis of molecular equilibrium data for stellar atmospheres

Interstellar molecular hydrogen abundance and possible source from giant stars

Interstellar extinction in UV by measurement of stellar energy distributions between 3000 and 1200 angstroms

Mie scattering calculation to support theory that interstellar extinction is caused by graphite particles

Geometrical UV reflectivity of Jupiter in terms of Rayleigh scattering determined from objective-grating rocket spectrometer

Jupiter photoelectric spectral scan in UV REPRODUCED as geometric reflectivity vs wavelength, using Aerobee rocket

Abundance of interstellar molecular hydrogen

Graphite particles and interstellar extinction

Jupiter photoelectric spectral scan in UV REPRODUCED as geometric reflectivity vs wavelength, using Aerobee rocket

Ultraviolet reflectivity of Jupiter from spectral scanning by Aerobee rocket spectrometers

We have detected absorption features in the far-ultraviolet spectrum of zeta Tau (B3pe), one of which corresponds to a new transition involving quasi-H/-/, and the other to a transition involving quasi-H2/+/. The former transition produces a broad absorption feature on the red wing of L-alpha. It is the result of the absorption of a photon by a ground-state hydrogen atom and colliding electron, and it leads to the excitation of both electrons to the 2p2 3Pe state of H/-/. more...

The total LTE opacity expected for a variety of temperatures and pressures has been calculated for a mixture of solar composition. The absorption coefficient for the H2 singlet transition between 1300 and 2000 A was obtained from computations at 5000 K by Sando and Dalgarno (1971). It is found that a correct estimate of the resonance broadening in Lyman-alpha wings leads to important modifications of the UV opacity. more...

Ultraviolet interstellar polarization measurements in the direction of Zed Ophiuchi by rocket-borne scanning spectrophotometer are reported. The spectrophotometer was calibrated by a beam of polarized light. Plotted percent polarization against inverse wavelength in microns shows that polarization is running around 1.5 percent for this star, which is consistent with the visual observation. more...

We discuss the possibility that vibrationally excited H2 may be collisionally de-excited, so providing a heating mechanism for interstellar clouds which operates by coupling the stellar radiation to the gas. The majority of excitations in the Lyman and Werner bands of H2 return the molecules to the ground electronic state in a vibrationally excited level, the most favoured being v'' = 7. We compare the hearing rate obtained in this way with other mechanisms which have been postulated, and present the results of calculations of temperature as a function of depth into clouds of different densities. more...

Reactions between atoms and ions of the interstellar medium and vibrationally excited molecular hydrogen are shown to produce a specific set of molecules. Molecules such as CO and CN can readily be produced in abundances greater than those of corresponding hydrides. When quantified in a simple manner the equilibrium density of molecules compares well with the observed values for the star Oph. more...

It is shown that the principal source of electrons in H I regions is the photoionization of vibrationally excited molecular hydrogen by starlight near 1000 A.

The possibility that vibrationally excited H2 may be collisionally de-excited, so providing a heating mechanism for interstellar clouds which operates by coupling the stellar radiation to the gas, is discussed. The majority of excitations in the Lyman and Werner bands of H2 return the molecules to the ground electronic state in a vibrationally excited level, the most favored level being 7. The heating rate obtained in this way is compared with other mechanisms which have been postulated, and the results of calculations of temperature as a function of depth into clouds of different densities are presented. It appears that this mechanism is a significant one, which should be taken into account in detailed models of dense clouds. more...