Topics in the physics of interstellar clouds

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1981

OSTI ID:6127697

Roberge, W G

Physical and chemical processes in interstellar clouds are discussed in six papers. In Collision-Induced Dissociation of H/sub 2/ and CO Molecules, the destruction of molecular hydrogen and carbon monoxide in shock-heated clouds is examined. Below a certain density n., radiative stabilization greatly reduces the dissociation rates with substantial consequences for the thermal and chemical evolution of the shocked gas. In The Penetration of Diffuse Ultraviolet Radiation into Interstellar Clouds, it is shown that the solution of the radiative transfer equation for coherent, nonconservative, anisotropic scattering of photons of dust grains can be expressed analytically, with arbitrary accuracy, by means of the spherical harmonics method. In Photoionization and Photodissociation in Diffuse Interstellar Clouds, this method is used to explore the dependence of photodestruction rates inside diffuse, plane parallel clouds to assumptions about the grain scattering properties. In The Calculation of Steady State Models of Diffuse Interstellar Clouds, a model of the xi Ophiuchi cloud is calculated including an accurate treatment of line and continuum radiative transfer. The abundances of certain molecules, including H/sub 2/ and OH, are sensitive to the radiative transfer calculation and models of diffuse clouds calculated with approximate treatments of radiative transfer may require substantial revision. In Cooling by C/sup +/ Ions in Interstellar Clouds, processes that determine the production and propagation of cooling radiation are examined and their effects on cooling rates in interstellar clouds are discussed.

• Research Organization: Harvard Univ., Cambridge, MA (USA)
• OSTI ID: 6127697
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CARBON COMPOUNDS
CARBON IONS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CHARGED PARTICLES
COOLING
COSMIC GASES
DISSOCIATION
ELEMENTS
ENERGY TRANSFER
FLUIDS
GASES
HYDROGEN
INTERSTELLAR GRAINS
INTERSTELLAR SPACE
IONIZATION
IONS
MOLECULES
NEBULAE
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PARTICLES
PLANETARY NEBULAE
SCATTERING
SPACE