Model dust envelopes around late-type stars

Journal Article · Fri Oct 15 04:00:00 EDT 1976 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/154746· OSTI ID:7137245

Jones, T W; Merrill, K M

Spectra have been computed for a large number of spherical model circumstellar dust shells, utilizing realistic grain opacities and assuming steady-state radiative equilibrium around cool stars. Results are shown graphically and the important model parameters evaluated for a wide range of shell optical depths, shell radii, and mass-distribution functions for both silicate and graphite dust grains.For shells containing silicate grains alone, the 10 ..mu.. feature can appear in absorption only when there is considerable optical depth at 10 ..mu.. in grains colder than approx.250 K. This condition can be relaxed somewhat when other warmer grain species coexisat.A clear-cut distinction exists between models involving ''dirty'' silicates which effectively absorb at short wavelengths and models involving ''clean'' silicates mixed with other, more absorptive grains. In the latter case, one must compute a separate energy balance for each grain species, the silicate species generally being much the colder. Results indicate that circumstellar silicate grains probably have greater absorptivities for 1 ..mu..approximately-less-thanlambdaapproximately-less-than5..mu.. than terrestrial silicates so far indicate. (AIP)

• Research Organization: National Radio Astronomy Observatory, Green Bank, West Virginia
• OSTI ID: 7137245
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 209:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CARBON
CHEMICAL COMPOSITION
COSMIC DUST
DIFFERENTIAL EQUATIONS
DUSTS
ELECTROMAGNETIC RADIATION
ELEMENTS
EQUATIONS
EQUATIONS OF MOTION
GIANT STARS
GRAPHITE
INFRARED RADIATION
MATHEMATICAL MODELS
NONMETALS
OPTICAL PROPERTIES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RADIATION TRANSPORT
RADIATIONS
SILICATES
SILICON COMPOUNDS
SPECTRA
STAR MODELS
STARS
SUPERGIANT STARS