Title: Composition and radiative properties of grains in molecular clouds and accretion disks
Abstract: view Abstract Citations (910) References (94) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Composition and Radiative Properties of Grains in Molecular Clouds and Accretion Disks Pollack, James B. ; Hollenbach, David ; Beckwith, Steven ; Simonelli, Damon P. ; Roush, Ted ; Fong, Wesley Abstract We define a model of the compositon and abundances of grains and gases in molecular cloud cores and accretion disks around young stars by employing a wide range of astronomical data and theory, the composition of primitive bodies in the solar system, and solar elemental abundances. In the coldest portions of these objects, we propose that the major grain species include olivine (Fe, Mg, 2SiO4), orthopyroxene (Fe, Mg, SiO3), volatile and refractory organics, water ice, troilite (FeS), and metallic iron. This compositional model differs from almost all previous models of the interstellar medium (ISM) by having organics as the major condensed C species, rather than graphite; by including troilite as a major grain species; and by specifying the mineralogical composition of the condensed silicates. Using a combination of laboratory measurements of optical constants and asymptotic theory, we derive values of the real and imaginary indices of refraction of these grain species over a wavelength range that runs from the vacuum ultraviolet (UV) to the radio domain. The above information on grain properties is used to estimate the Rosseland mean opacity of the grains and their monochromatic opacity. Publication: The Astrophysical Journal Pub Date: February 1994 DOI: 10.1086/173677 Bibcode: 1994ApJ...421..615P Keywords: Accretion Disks; Astronomical Models; Cosmic Dust; Interstellar Matter; Molecular Clouds; Stellar Composition; Stellar Mass Accretion; Abundance; Grain Size; Iron; Olivine; Pyroxenes; Water; Astrophysics; ACCRETION; ACCRETION DISKS; ISM: DUST; EXTINCTION; ISM: MOLECULES full text sources ADS |