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Theoretical spectra of circumstellar dust shells around carbon-rich asymptotic giant branch starsRealistic modeling of circumstellar dust shells around evolved stars has to include a physical treatment of the interaction among hydrodynamics, thermodynamics, radiative transfer, chemistry and dust formation and -growth. A self-consistent solution of this problem is presented in the case of stationary, spherical symmetric dust-driven winds. The resulting shell structure and the mass-loss rate are completely determined by the three fundamental stellar parameters stellar mass M(stellar), stellar luminosity L(stellar) and effective temperature T(sub eff) and by the element abundances epsilon(sub i). A detailed calculation of the transport coefficients of the dust component by means of the particle size distribution function and the solution of the non-grey radiative transfer problem provide realistic synthetic spectra of the dust shell models. We discuss the dependence of the resulting spectra on the stellar parameters in terms of infrared two color diagrams. Application of these model calculations to the prominent infrared object IRC +10216 yields best agreement with the observed spectrum and the visibility data at maximum light for the stellar parameters M(stellar) = 0.7 solar mass, L(stellar) = 2.4 x 10(exp 4) solar luminosity, T(stellar) = 2010K and a carbon to oxygen ratio of epsilon(sub c)/epsilon(sub o) = 1.40, which corresponds to a mass-loss rate of M-dot = 8 x 10(exp -5) solar mass/yr. In this model only amorphous carbon grains are considered as the main opacity source. From this model a distance to IRC +10216 of d = 170pc is deduced. The total mass contained in the circumstellar dust shell implies and initial main sequence mass of M(sub ZAMS) greater than or = 1.3 solar mass for IRC +10216.
Document ID
19950060205
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Winters, J. M.
(Technische Universitat Berlin, Berlin, Germany)
Dominik, C.
(NASA Ames Research Center Moffett Field, CA, United States)
Sedlmayr, E.
(Technische Universitat Berlin, Berlin, Germany)
Date Acquired
August 16, 2013
Publication Date
August 1, 1994
Publication Information
Publication: Astronomy and Astrophysics
Volume: 288
Issue: 1
ISSN: 0004-6361
Subject Category
Astrophysics
Accession Number
95A91804
Funding Number(s)
CONTRACT_GRANT: DFG-SE-420/4-3
Distribution Limits
Public
Copyright
Other

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