Radiative transfer in spherical circumstellar dust envelopes. IV. The infrared emissivity profile and composition of the dust in NGC 7027.
Abstract
Using radiative transfer methods described in previous papers, dust-emission models of the bright planetary nebula NGC 7027 have been calculated. Analysis of the infrared continuum of NGC 7027 based upon these calculations shows the following. First, if the spatial dust distribution coincides with the ionized gas distribution as given by Scott (1973), the infrared continuum may be produced by an unknown substance whose infrared emissivity declines with increasing wavelength to about 50 microns and then rises. Second, if there exists a cool outer dust shell beyond 5 to 6 sec from the central source, the observed infrared continuum may be produced by iron grains of radius 1 micron or by a mixture of smaller iron and graphite grains.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 1976
- DOI:
- 10.1086/154061
- Bibcode:
- 1976ApJ...203..177A
- Keywords:
-
- Cosmic Dust;
- Infrared Spectra;
- Planetary Nebulae;
- Radiative Transfer;
- Stellar Envelopes;
- Astrophysics;
- Continuous Spectra;
- Infrared Astronomy;
- Interstellar Matter;
- Spatial Distribution;
- Astrophysics