Internal Dust in Gaseous Nebulae. II. Absorption of Lyman-Continuum Radiation by Dust

Abstract

view Abstract Citations (78) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Internal Dust in Gaseous Nebulae. II. Absorption of Lyman-Continuum Radiation by Dust Mathis, John S. Abstract The ionization structure of model nebulae containing hydrogen, hellum, and isotropically scattering dust is discussed. The ultraviolet optical depth r and albedo are parameters. The only relevant property of the stellar radiation is y, the ratio of the number of helium-ionizing to hydrogen4onizing photons. The fraction of ionizing photons absorbed by the gas is plotted in a figure as a function of r (1 - ), the optical depth for pure absorption, which alone determines the effect of the dust. Definite results for real nebulae must wait on better determinations of optical properties of dust. For purposes of illustrating the magnitude of possible effects, it was assumed that the ultraviolet optical depth for absorption equals the total optical depth (absorption plus scattering) for H . The r (HP) was determined for NGC 6514 and NGC 6523 from the H photometry of O'Dell, Hubbard, and Peimbert. The internal dust requires an increase in the estimated T0ff for the central stars of 1200 -2000 K for NGC 6514 and K for NGC 6523, depending on the albedo of the dust at HP. The gas/dust ratio is also estimated. Publication: The Astrophysical Journal Pub Date: August 1971 DOI: 10.1086/151029 Bibcode: 1971ApJ...167..261M full text sources ADS |