Interpretation of Carbon Stars Spectra from Model Atmospheres Computations

Querci, F.; Querci, M.

doi:10.1007/978-94-010-2211-8_24

Cited by 31 publications

(37 citation statements)

References 3 publications

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“…Clearly the effect of the detailed opacities from polyatomic species and eventually grains, are not fully taken into account in the coolest models. We conclude there is a rough agreement with the mean values as quoted in Table 3, but further investigations with more realistic models are necessary to fully assess the cool end of the Querci et al (1974) sequence. We have collected in Table 7 the best estimates of effective temperatures from the three methods used -direct values from occultation and/or interferometric diameters (Table 3); -SED comparisons between observations and models; -batch of five calibrated color indices (Eq.…”

Section: The Mean Seds Of the Photometric Groups And Model Atmospheresupporting

confidence: 74%

“…8 for the mean (observed) SED of the HC1-group with T eff = 4710 K assumed, which yields the best agreement with the DE12 model of Querci et al (1974) with T eff = 4500 K and log g = −1.0. From various trials, we thus adopt T eff 4710 ± 200 K as the mean effective temperature for the HC1 group.…”

Section: The Mean Seds Of the Photometric Groups And Model Atmospherementioning

confidence: 59%

“…The comparison is shown in Fig. 9 of the mean SED of HC5 (T eff = 3500 K) to the predictions for the DE12 model at T eff = 3400 K and log g = −1.0 of Querci et al (1974). The global shape is satisfactorily reproduced but discrepancies in the details are noticed.…”

Section: The Mean Seds Of the Photometric Groups And Model Atmospherementioning

confidence: 86%

“…The estimated accuracy should be slightly better than ±100 K, possibly ±80 K. These results are consistent with the mean direct effective temperatures as quoted in Table 3. We used older models from Querci et al (1974) and Querci & Querci (1976) for the hotter HC-stars. The value C/O 3.5 they adopted seems too high when compared to the results of Lambert et al (1986) for the CV stars (C/O ≤ 2.0).…”

Section: The Mean Seds Of the Photometric Groups And Model Atmospherementioning

confidence: 99%

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The effective temperatures of carbon-rich stars

Bergeat

Knapik

Rutily

2001

A&A

151

207

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Abstract. We evaluate effective temperatures of 390 carbon-rich stars. The interstellar extinction on their lines of sights was determined and circumstellar contributions derived. The intrinsic (dereddened) spectral energy distributions (SEDs) are classified into 14 photometric groups (HCi, CVj and SCV with i = 0,5 and j = 1,7). The new scale of effective temperatures proposed here is calibrated on the 54 angular diameters (measured on 52 stars) available at present from lunar occultations and interferometry. The brightness distribution on stellar discs and its influence on diameter evaluations are discussed. The effective temperatures directly deduced from those diameters correlate with the classification into photometric groups, despite the large error bars on diameters. The main parameter of our photometric classification is thus effective temperature. Our photometric k 1/2 coefficients are shown to be angular diameters on a relative scale for a given photometric group, (more precisely for a given effective temperature). The angular diameters are consistent with the photometric data previously shown to be consistent with the true parallaxes from HIPPARCOS observations (Knapik, et al. 1998, Sect. 6). Provisional effective temperatures, as constrained by a successful comparison of dereddened SEDs from observations to model atmosphere predictions, are in good agreement with the values directly calculated from the observed angular diameters and with those deduced from five selected intrinsic color indices. These three approaches were used to calibrate a reference angular diameter Φ0 and the associated coefficient CT eff . The effective temperature proposed for each star is the arithmetic mean of two estimates, one ("bolometric") from a reference integrated flux F0, the other ("spectral") from calibrated color indices which are representative of SED shapes. Effective temperatures for about 390 carbon stars are provided on this new homogeneous scale, together with values for some stars classified with oxygen-type SEDs with a total of 438 SEDs (410 stars) studied. Apparent bolometric magnitudes are given. Objects with strong infrared excesses and optically thick circumstellar dust shells are discussed separately. The new effective temperature scale is shown to be compatible and (statistically) consistent with the sample of direct values from the observed angular diameters. The effective temperatures are confirmed to be higher than the mean color temperatures (from 140 to 440 K). They are in good agreement with the published estimates from the infrared flux method for T eff ≥ 3170 K, while an increasing discrepancy is observed toward lower temperatures. As an illustration of the efficiency of the photometric classification and effective temperature scale, the C/O ratios and the Merrill-Sanford (M-S) band intensities are investigated. It is shown that the maximum value, mean value and dispersion of C/O increase along the photometric CV-sequence, i.e. with decreasing effective temperature. The M-S bands of SiC2 are sho...

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Section: The Mean Seds Of the Photometric Groups And Model Atmospheresupporting

confidence: 74%

Section: The Mean Seds Of the Photometric Groups And Model Atmospherementioning

confidence: 59%

Section: The Mean Seds Of the Photometric Groups And Model Atmospherementioning

confidence: 86%

Section: The Mean Seds Of the Photometric Groups And Model Atmospherementioning

confidence: 99%

See 2 more Smart Citations

The effective temperatures of carbon-rich stars

Bergeat

Knapik

Rutily

2001

A&A

151

207

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“…To determine the contribution of the various molecules to an individual spectral feature, we calculated synthetic spectra using the COMARCS models of Aringer et al (2009). The line lists of CN and C 2 that we used were those from Jørgensen (1997) and Querci et al (1974), respectively. For the model parameters we applied the values of Kipper (2004).…”

Section: Hd 134453 (X Tra)mentioning

confidence: 99%

Crires-Pop

Lebzelter

Seifahrt

Uttenthaler

et al. 2012

A&A

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Context. New instrumental capabilities and the wealth of astrophysical information extractable from the near-infrared wavelength region have led to a growing interest in the field of high resolution spectroscopy at 1-5 μm. Aims. We aim to provide a library of observed high-resolution and high signal-to-noise-ratio near-infrared spectra of stars of various types throughout the Hertzsprung-Russell diagram. This is needed for the exploration of spectral features in this wavelength range and for comparison of reference targets with observations and models. Methods. High quality spectra were obtained using the CRIRES near-infrared spectrograph at ESO's VLT covering the range from 0.97 μm to 5.3 μm at high spectral resolution. Accurate wavelength calibration and correction for telluric lines were performed by fitting synthetic transmission spectra for the Earth's atmosphere to each spectrum individually. Results. We describe the observational strategy and the current status and content of the library which includes 13 objects. The first examples of finally reduced spectra are presented. This publication will serve as a reference paper to introduce the library to the community and explore the extensive amount of material.

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High Resolution Spectra of M and C Stars by Fourier Transform Spectroscopy

Maillard

1974

Highlights of Astronomy

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Interpretation of Carbon Stars Spectra from Model Atmospheres Computations

Cited by 31 publications

References 3 publications

The effective temperatures of carbon-rich stars

The effective temperatures of carbon-rich stars

Crires-Pop

High Resolution Spectra of M and C Stars by Fourier Transform Spectroscopy

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