Astrophysics of nebulae and active galactic nuclear emission-line regions: new methods and applications

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:6894624

Cota, S A

This dissertation considers five problems of current interest in studies of nebulae and active galactic nuclear emission-line regions. First, effects of electron collisions on the populations of the highly excited states (n from 10 to 100) of ions are examined. It is demonstrated that 3-body recombinations to these states enhance the total recombination rate in cold nova shells and broad-line regions of active galactic nuclei (AGN). Second, treatment of the hydrogen atom in photoionization models is discussed. Applicability and accuracy of l-mixing and the published collision rates are discussed. Third, the author predicts the helium singlet recombination spectrum for cases of finite optical depth (i.e., intermediate between cases A and B), and allows for the destruction of He I resonance photons through photoionizations of neutral hydrogen. Fourth, the predicts the H..beta.. emissivity for cases of finite optical depth, and allow for the destruction of Lyman photons on dust grains before they can attain case B. Finally, he demonstrates through photoionization modeling of its fine structure line spectrum, that the center of our galaxy, Sgr A West, is ionized by a soft spectrum like that of a 35,000 K star.

• Research Organization: Ohio State Univ., Columbus (USA)
• OSTI ID: 6894624
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
640105 -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BALMER LINES
CHARGED PARTICLES
COLLISIONS
ELECTRON COLLISIONS
EMISSION SPECTRA
ENERGY LEVELS
EXCITED STATES
GALAXY NUCLEI
IONIZATION
IONS
NEBULAE
PHOTOIONIZATION
SPECTRA