A Dust-Radiation Instability in Ionized Nebulae

Abstract

view Abstract Citations (6) References (11) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Dust-Radiation Instability in Ionized Nebulae Nordsieck, Kenneth H. Abstract Inhomogeneities in planetary nebulae and H ii regions may be formed by the pressure of trapped resonance4ine radiation on dust grains For a large range in physical conditions in such nebulae, the formation time of sizable regions of abnormal dust content is considerably less than the lifetime of the nebulae. The dust and gas, however, are only weakly coupled: the dust perturbation is ahvays at least 10 times the ionized-gas perturbation. The resulting grain-enriched gas may later form into a star with peculiar abundance characteristics, if the region of perturbation is large enough to include a stellar mass of gas. A conventional linear perturbation approach is used to obtain the e-folding time of a dust-density perturbation from a set of differential equations describing the motion and interaction of the dust and gas fluids, the ionization balance of hydrogen, and the diffusion of La line radiation. Also, an estimate of the La density caused by cosmic-ray ionization and excitation of neutral hydrogen in interstellar clouds shows that the instability may be marginally active there for regions less than 1 pc in size (corresponding to included gas masses / < 1). Publication: The Astrophysical Journal Pub Date: January 1971 DOI: 10.1086/150767 Bibcode: 1971ApJ...163..287N full text sources ADS |