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J/A+A/328/349       Role of Convection in A, F, and G stars   (Smalley+ 1997)

The role of convection on the uvby colours of A, F, and G stars Smalley B., Kupka F. <Astron. Astrophys. 328, 349 (1997)> =1997A&A...328..349S (SIMBAD/NED BibCode)
ADC_Keywords: Models, atmosphere ; Abundances ; Photometry, uvby Keywords: convection - stars: atmospheres - stars: general - stars: fundamental parameters - stars: late-type Description: We discuss the effects of convection on the theoretical uvby colours of A, F, and G stars. The standard mixing-length theory atlas9 models of Kurucz (1993, ATLAS9, SAO, Cambridge, USA), with and without approximate overshooting, are compared to models using the turbulent convection theory proposed by Canuto & Mazzitelli (1991ApJ...370..295C, 1992ApJ...389..724C) and implemented by Kupka (1996, ASPConf. Proc. 108, 73). Comparison with fundamental Teff and log g stars reveals that the Canuto & Mazzitelli models give results that are generally superior to standard mixing-length theory (MLT) without convective overshooting. MLT models with overshooting are found to be clearly discrepant. This is supported by comparisons of non-fundamental stars, with Teff obtained from the Infrared Flux Method and log g from stellar evolutionary models for open cluster stars. The Canuto & Mazzitelli theory gives values of (b-y)0 and c0 that are in best overall agreement with observations. Investigations of the m0 index reveal that all of the treatments of convection presented here give values that are significantly discrepant for models with Teff<6000K. It is unclear as to whether this is due to problems with the treatment of convection, missing opacity, or some other reason. None of the models give totally satisfactory m0 indices for hotter stars, but the Canuto & Mazzitelli models are in closest overall agreement above 7000K. Grids of uvby colours, based on the CM treatment of convection, are presented. These grids represent an improvement over the colours obtained from models using the mixing-length theory. The agreement with fundamental stars enables the colours to be used directly without the need for semi-empirical adjustments that were necessary with the earlier colour grids. For a description of the uvby photometric system, see e.g. GCPD/04 File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file cm_p10.dat 57 169 *Canuto & Mazzitelli (CM) grid for [M/H] = +1.0 cm_p05.dat 57 169 CM grid for [M/H] = +0.5 cm_p00.dat 57 169 CM grid for [M/H] = +0.0 cm_m05.dat 57 169 CM grid for [M/H] = -0.5 cm_m10.dat 57 169 CM grid for [M/H] = -1.0 table5 79 86 Comparison between evolutionary and grid log g
Note to cm_p10.dat: Canuto & Mazzitelli models, 1991ApJ...370..295C and 1992ApJ...389..724C. Byte-by-byte Description of file: cm*.dat
Bytes Format Units Label Explanations
1- 5 I5 K Teff Teff 8- 11 F4.2 [cm/s2] log(g) log g 13- 17 F5.2 [Sun] [M/H] Metallicity [M/H] 20- 23 F4.2 km/s Vturb microturbulence 29- 33 F5.3 mag u-b u-b colour index 37- 41 F5.3 mag b-y b-y colour index 45- 49 F5.3 mag m1 m1 colour index 53- 57 F5.3 mag c1 c1 colour index
Byte-by-byte Description of file: table5
Bytes Format Units Label Explanations
1- 5 I5 --- HD HD (Cat. III/135) number 7- 10 I4 K Teff Teff from Kunzli et al. (1997, Cat. J/A+AS/122/51) 12- 15 F4.2 [cm/s2] logg logg from evolutionary models (Kunzli et al., 1997, Cat. J/A+AS/122/51) 18- 22 F5.3 mag b-y b-y colour index 24- 28 F5.3 mag c0 c0 colour index 31- 34 I4 K Teff(CM) Teff from CM (Canuto & Mazzitelli) grid (1) 36- 39 F4.2 [cm/s2] logg(CM) logg from CM grid 41- 45 F5.2 [cm/s2] Dlogg(CM) Delta logg for CM grid 48- 51 I4 K Teff(noOV) Teff from MLT (mixing-length theory) noOV grid 53- 56 F4.2 [cm/s2] logg(noOV) logg from MLT noOV grid 58- 62 F5.2 [cm/s2] Dlogg(noOV) Delta logg for MLTnoOV grid 65- 68 I4 K Teff(OV) Teff from MLT OV grid 70- 73 F4.2 [cm/s2] logg(OV) logg from MLT OV grid 75- 79 F5.2 [cm/s2] Dlogg(OV) Delta logg for MLT OV grid
Note (1): Canuto & Mazzitelli models, 1991ApJ...370..295C and 1992ApJ...389..724C.
Acknowledgements: Barry Smalley
(End) Patricia Bauer [CDS] 30-Jul-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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