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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 (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:
FileName Lrecl Records Explanations
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
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
Bytes Format Units Label Explanations
1- 10 A10 --- IRAS IRAS name 12- 20 A9 --- Name Name from Yamashita (1972AnTok..13..169Y, 1975AnTok..15...47Y) 22- 27 A6 --- SpType Spectral type from Yamashita (1972AnTok..13..169Y, 1975AnTok..15...47Y) 29- 34 A6 --- IRC IRC identification (Neugebauer & Leighton 1969IRC...C......0N) 37- 41 A5 --- RAFGL RAFGL identification (Price & Murdock 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 3mum (1) 51 A1 --- 8.6um Presence and intensity of the band at 8.6mum (1) 53 A1 --- 14um Presence and intensity of the band at 14mum (1)
Note (1): a - weak b - intermediate c - strong
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
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

(End) Patricia Bauer [CDS] 18-Dec-1997
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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