J/A+A/503/913 Synthetic spectrophotometry for C-rich giants (Aringer+, 2009)
Synthetic photometry for carbon rich giants. I. Hydrostatic dust-free models.
Aringer B., Girardi L., Nowotny W., Marigo P., Lederer M.T.
<Astron. Astrophys., 503, 913-928 (2009)>
=2009A&A...503..913A 2009A&A...503..913A
ADC_Keywords: Models, evolutionary ; Photometry ; Spectroscopy
Keywords: stars: late-type - stars: AGB and post-AGB - stars: atmospheres -
infrared: stars - stars: carbon -
Hertzsprung-Russell (HR) and C-M diagrams
Abstract:
Carbon rich objects represent an important phase during the late
stages of evolution of low and intermediate mass stars. They
contribute significantly to the chemical enrichment and to the
infrared light of galaxies. A proper description of their atmospheres
is crucial for the determination of fundamental parameters such as
effective temperature or mass loss rate. We study the spectroscopic
and photometric properties of carbon stars. In the first paper of this
series we focus on objects that can be described by hydrostatic models
neglecting dynamical phenomena like pulsation and mass loss. As a
consequence, the reddening due to circumstellar dust is not included.
Our results are collected in a database, which can be used in
conjunction with stellar evolution and population synthesis
calculations involving the AGB. We have computed a grid of 746
spherically symmetric COMARCS atmospheres covering effective
temperatures between 2400 and 4000K, surface gravities from
log(g[cm/s2])=0.0 to -1.0, metallicities ranging from the solar
value down to one tenth of it and C/O ratios in the interval between
1.05 and 5.0. Subsequently, we used these models to create synthetic
low resolution spectra and photometric data for a large number of
filter systems. The tables including the results are electronically
available. First tests of the application on stellar evolution
calculations are shown.
We have selected some of the most commonly used colours in order to
discuss their behaviour as a function of the stellar parameters. A
comparison with measured data shows that down to 2800K the agreement
between predictions and observations of carbon stars is good and our
results may be used to determine quantities like the effective
temperature. Below this limit the synthetic colours are much too blue.
The obvious reason for these problems is the neglect of circumstellar
reddening and structural changes due to pulsation and mass loss.
Description:
The following bolometric correction tables have been calculated from
COMA07/SPHREAD03 spectra based on COMARCS04 hydrostatic models.
Reddening due to circumstellar dust is not included. Each of the 36
tables contains a photometric system including different filters. If a
certain filter curve is not covered by the synthetic spectra (below
4444 and above 250000A) a value of -999999 is listed for the
bolometric correction. Details concerning the photometric systems are
given in Marigo, P., Girardi, L., Bressan, A., et al.,
2008A&A...482..883M 2008A&A...482..883M and in
http://stev.oapd.inaf.it/~lgirardi/cmd_2.1/photsys.html .
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
photom.dat 141 36 List of photometric system files
spectra.dat 89 746 List of spectra
phot/* . 36 Individual photometric files
with bolometric corrections
spec/* . 746 Individual synthetic spectra
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Byte-by-byte Description of file: photom.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- FileName Name of the file in subdirectory phot
17-141 A125 --- Filt Filters for which bolometric corrections are
presented in the file
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Byte-by-byte Description of file: spectra.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Mod [1/746] Model number
7 I1 --- Ver [3/4] Version of COMARCS model
9- 12 I4 K Teff [2400/4000] Effective temperature
14- 18 F5.2 [cm/s2] logg [-1.00/+0.00] Surface gravity
20- 24 F5.2 solMass Mass [1/99] Mass
26- 29 F4.2 Sun Z (0.10, 0.33, 1.00) Metallicity
(in solar metallicity)
32- 35 F4.2 --- C/O [1.05/5.00] C/O abundance ratio
37- 39 F3.1 km/s xi [2.5] Microturbulent velocity
41- 89 A49 --- SpFileName Name of the spectrum in subdirectory spec
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Byte-by-byte Description of file: phot/*
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Bytes Format Units Label Explanations
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1- 4 I4 --- Mod [1/746] Model number
10- 13 I4 K Teff Effective temperature
15- 19 F5.2 [cm/s2] logg Surface gravity
21- 24 F4.1 solMass Mass Mass
26- 30 F5.2 [Sun] Z Metallicity (in solar metallicity)
32- 36 F5.2 --- C/O C/O abundance ratio
38- 42 F5.2 [solLum] logL Luminosity
44- 47 F4.1 km/s xi microturbulent velocity
50 I1 --- Ver [3/4] Version of COMARCS model
51- 58 A8 --- Band1 Band name
60- 66 F7.3 mag BC1 ?=- Bolometric correction in Band1 filter (1)
69- 76 A8 --- Band2 Band name
79- 85 F7.3 mag BC2 ?=- Bolometric correction in Band2 filter (1)
88- 95 A8 --- Band3 Band name
98-104 F7.3 mag BC3 ?=- Bolometric correction in Band3 filter (1)
107-114 A8 --- Band4 Band name
117-123 F7.3 mag BC4 ?=- Bolometric correction in Band4 filter (1)
126-133 A8 --- Band5 Band name
136-142 F7.3 mag BC5 ?=- Bolometric correction in Band5 filter (1)
145-152 A8 --- Band6 Band name
155-161 F7.3 mag BC6 ?=- Bolometric correction in Band6 filter (1)
164-171 A8 --- Band7 Band name
173-179 F7.3 mag BC7 ?=- Bolometric correction in Band7 filter (1)
182-189 A8 --- Band8 Band name
192-198 F7.3 mag BC8 ?=- Bolometric correction in Band8 filter (1)
201-208 A8 --- Band9 Band name
211-217 F7.3 mag BC9 ?=- Bolometric correction in Band9 filter (1)
220-227 A8 --- Band10 Band name
230-236 F7.3 mag BC10 ?=- Bolometric correction in Band10 filter (1)
238-246 A9 --- Band11 Band name
249-255 F7.3 mag BC11 ?=- Bolometric correction in Band11 filter (1)
257-265 A9 --- Band12 Band name
268-274 F7.3 mag BC12 ?=- Bolometric correction in Band12 filter (1)
276-284 A9 --- Band13 Band name
287-293 F7.3 mag BC13 ?=- Bolometric correction in Band13 filter (1)
296-303 A8 --- Band14 Band name
306-312 F7.3 mag BC14 ?=- Bolometric correction in Band14 filter (1)
315-322 A8 --- Band15 Band name
325-331 F7.3 mag BC15 ?=- Bolometric correction in Band15 filter (1)
334-341 A8 --- Band16 Band name
344-350 F7.3 mag BC16 ?=- Bolometric correction in Band16 filter (1)
353-360 A8 --- Band17 Band name
362-368 F7.3 mag BC17 ?=- Bolometric correction in Band17 filter (1)
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Note (1): If a certain filter curve is not covered by the synthetic spectra
(below 4444 and above 250000Å) a value of --- is listed for the
bolometric correction.
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Byte-by-byte Description of file: spec/*
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Bytes Format Units Label Explanations
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2- 11 F10.3 0.1nm lambda Wavelength
15- 20 F6.4 --- nFlux [0/2] Continuum normalized flux (1)
22- 31 E10.5 10-7W nuL(nu) Frequency times specific luminosity
ν.Lν
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Note (1): Normalized to calculation without atomic and molecular line opacities
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Acknowledgements:
Aringer Bernhard, aringer (at)astro.univie.ac.at
(End) Bernhard Aringer [INAF, Padova], Patricia Vannier [CDS] 08-Sep-2009