Abo Bibliothek: Guest
ICHMT DL Home Aktuelles Jahr Archive Vorstand International Centre for Heat and Mass Transfer


DOI: 10.1615/ICHMT.1995.RadTransfProc.570

Zeljko Ivezic
Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506-0055, USA

Moshe Elitzur
Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506-0055, USA


Astronomical objects usually appear as point sources since most observations are incapable of resolving them. Thus the only way to infer the nature of a source is spectral analysis of observed flux. Many objects are embedded in a dusty envelope which scatters, absorbs and re-radiates the radiation emitted by the underlying source. As a result, spectra of these objects are shifted toward the infrared wavelengths.
For dust heated only by the radiation field we show that the resulting spectral shape does not depend on the spatial dimensions of the underlying source and envelope. The only parameters that specify the radiative transfer problem are the overall optical depth and, unlike for plan-parallel geometry, the functional form of the dust spatial distribution. The properties of the central source enter only through its spectral shape and are not important at the infrared wavelengths considered here. Consequently, for a given dust chemical composition, the resulting spectrum is fully determined by the dust spatial distribution and overall optical depth. This conclusion is of great importance since objects of different nature are expected to have different dust spatial distributions, dependent mainly on whether the envelope is collapsing onto or expanding away from the central source. Thus, detailed radiative transfer modeling can provide efficient methods to determine the amount of dust, its chemical composition and the nature of the object which emitted the observed spectrum.
Our models show that observations obtained by the Infrared Astronomical Satellite (IRAS) can indeed be interpreted in terms of the overall optical depth and dust spatial distributions. Preliminary comparison with results obtained for some sources by other methods verify the basic premises and show that reliable classification of all sources observed by IRAS is feasible.

ICHMT Digital Library

Bow shocks on a jet-like solid body shape. Thermal Sciences 2004, 2004. Pulsed, supersonic fuel jets - their characteristics and potential for improved diesel engine injection. PULSED, SUPERSONIC FUEL JETS - THEIR CHARACTERISTICS AND POTENTIAL FOR IMPROVED DIESEL ENGINE INJECTION
View of engine compartment components (left). Plots of temperature distributions in centreplane, forward of engine (right). CHT-04 - Advances in Computational Heat Transfer III, 2004. Devel... DEVELOPMENT AND CURRENT STATUS OF INDUSTRIAL THERMOFLUIDS CFD ANALYSIS
Pratt & Whitney's F-135 Joint Strike Fighter Engine under test in Florida is a 3600F class jet engine. TURBINE-09, 2009. Turbine airfoil leading edge stagnation aerodynamics and heat transfe... TURBINE AIRFOIL LEADING EDGE STAGNATION AERODYNAMICS AND HEAT TRANSFER - A REVIEW
Refractive index reconstructed field. (a) Second iteration. (b) Fourth iteration. Radiative Transfer - VI, 2010. Theoretical development for refractive index reconstruction from a radiative ... THEORETICAL DEVELOPMENT FOR REFRACTIVE INDEX RECONSTRUCTION FROM A RADIATIVE TRANSFER EQUATION-BASED ALGORITHM
Two inclusion test, four collimated sources. Radiative Transfer - VI, 2010. New developments in frequency domain optical tomography. Part II. Application with a L-BFGS associated to an inexa... NEW DEVELOPMENTS IN FREQUENCY DOMAIN OPTICAL TOMOGRAPHY. PART II. APPLICATION WITH A L-BFGS ASSOCIATED TO AN INEXACT LINE SEARCH