J/A+A/330/505 Carbon stars IR emission (Blanco+ 1998)
Circumstellar emission from dust envelopes around carbon stars showing
the silicon carbide feature
Blanco A., Borghesi A., Fonti S., Orofino V.
<Astron. Astrophys. 330, 505 (1998)>
=1998A&A...330..505B 1998A&A...330..505B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, carbon ; Infrared sources
Keywords: stars: carbon - stars: circumstellar matter - infrared: stars
Abstract:
Spectroscopic and photometric data relative to a sample of 55 carbon
stars showing the 11.3µm feature have been fitted in the wavelength
range between 0.4 and 100µm by means of a radiative transfer model
using the laboratory extinction spectra of amorphous carbon and
silicon carbide (SiC) grains. The transfer code allows to determine in
a self-consistent way the grain equilibrium temperature of the various
species at different distances from the central star and gives all the
relevant circumstellar parameters which can be very important for the
evolutionary study of carbon stars. In order to get meaningful
information on the nature and physical properties of the dust grains
responsible for the 11.3µm feature and the underlying continuum,
the fitting procedure of the spectr a has been applied individually to
every single source. For this reason it has been possible to take into
account any variation in position and shape of the band from source to
source. Our analysis show that all the sources, in addition to the
amorphous carbon grains accounting for the continuum emission, need
always the presence of α-SiC particles while some of them
require also β-SiC. Moreover, the presence of one or both types
of SiC particles seems not correlated neither with the total optical
thickness nor with any other physical and geometrical parameters of
the circumstellar envelope. The best-fit parameters found in this work
have been used to calculate the mass-loss rate from the central stars.
The clear correlation, that we find between the strength of the SiC
feature and the total mass loss-rate, confirms the results already
found by other authors for the same kind of sources and derived from
the observed CO emission lines.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 54 55 The carbon star sample
table2.dat 45 55 Best-fit model parameters of our IRAS source
sample and computed mass-loss rates
tables.tex 78 157 LaTeX version of the tables
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See also:
II/198 : Vilnius photometry of carbon stars (Paupers+, 1993)
III/156 : Cool Galactic Carbon Stars, 2nd Edition (Stephenson 1989)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- IRAS IRAS name
12- 20 A9 --- Name Name from Yamashita
(1972AnTok..13..169Y 1972AnTok..13..169Y, 1975AnTok..15...47Y 1975AnTok..15...47Y)
22- 27 A6 --- SpType Spectral type from Yamashita
(1972AnTok..13..169Y 1972AnTok..13..169Y, 1975AnTok..15...47Y 1975AnTok..15...47Y)
29- 34 A6 --- IRC IRC identification
(Neugebauer & Leighton 1969IRC...C......0N 1969IRC...C......0N)
37- 41 A5 --- RAFGL RAFGL identification
(Price & Murdock 1983AFGL..161.....P 1983AFGL..161.....P)
44- 47 I4 --- CS Number in the General Catalogue of Cool Carbon
Stars (Stephenson 1989, Cat. III/156)
49 A1 --- 3um Presence and intensity of the band at 3µm (1)
51 A1 --- 8.6um Presence and intensity of the band at 8.6µm (1)
53 A1 --- 14um Presence and intensity of the band at 14µm (1)
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Note (1): a - weak
b - intermediate
c - strong
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- IRAS IRAS name
12- 14 F3.1 --- tau Optical thickness
16- 19 I4 K T* Stellar temperature
21- 23 F3.1 --- RI/R* Enveloppe inner radius versus stellar radius
25- 29 E5.0 --- RE/RI Enveloppe outer radius versus stellar radius
31- 32 I2 % AC AC submicronic grains percentage
34- 35 I2 % alpha α-SiC submicronic grains percentage
37- 38 I2 % beta ? β-SiC submicronic grains percentage
40- 45 E6.1 solMass/yr dM/dt Computed mass-loss rate
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(End) Patricia Bauer [CDS] 18-Dec-1997