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J/A+A/454/333       Computed Hbeta indices from ATLAS9 model   (Castelli+, 2006)

Computed Hβ indices from ATLAS9 model atmospheres. Castelli F., Kurucz R.L. <Astron. Astrophys. 454, 333 (2006)> =2006A&A...454..333C
ADC_Keywords: Models, atmosphere ; Abundances, [Fe/H] ; Photometry, H-beta Keywords: stars: atmospheres - stars: fundamental parameters - techniques: photometric Abstract: Grids of Hβ indices based on updated (new-ODF) ATLAS9 model atmospheres were computed for solar and scaled solar metallicities [+0.5], [+0.2], [0.0], [-0.5], [-1.0], [-1.5], [-2.0], [-2.5] and for alpha enhanced compositions [+0.5a], [0.0a], [-0.5a], [-1.0a], [-1.5a], [-2.0a], [-2.5a], and [-4.0a]. Indices for Teff>5000K were computed with the same methods as described by Lester, Gray & Kurucz (1986ApJS...61..509L) (LGK86) except for a different normalization of the computed natural system to the standard system. LGK86 used special ODFs to compute the fluxes. For Teff less or equal to 5000K we computed the fluxes using the synthetic spectrum method. In order to assess the accuracy of the computed indices comparisons were made with the indices computed by Smalley & Dworetsky (1995A&A...293..446S) (MD95) and with the empirical relations Teff-Hβ given by Alonso et al. (1996A&A...313..873A) for several metallicities. Furthermore, for cool stars, temperatures inferred from the computed indices were compared with those of the fundamental stars listed by MD95. The same kind of comparison was made between gravities for B-type stars. The temperatures from the computed indices are in good agreement, within the error limits, with the literature values for Teff between 4750K and 8000K, while the gravities agree for Teff>9000K. The computed Hβ indices for the Sun and for Procyon are very close to the observed values. The comparison between the observed and computed Hβ indices as function of the observed Hβ has shown a very small trend which almost completely disappears when only stars hotter than 10000K are considered. The trend due to the cool stars is probably related with the low accuracy of the fundamental Teff which are affected by large errors for most of the stars. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 73 8092 Hβ indices for 16 different metallicities and Vturb=2km/s and for [M/H]=0.0 and Vturb=0.
See also: J/A+A/333/231 : O-M stars model atmospheres (Bessell+ 1998) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 13 A13 --- Seq Sequential designation of the model (1) 17- 19 I3 --- Model [1/476] Model number for given [M/H] and Vturb 21- 25 I5 K Teff Effective temperature 27- 31 F5.2 [cm/s2] logg Gravity surface 33- 37 F5.2 [Sun] [M/H] Fixed metallicity, log[N(Fe)/N(Fe_Sun_)] (2) 38 A1 --- n_[M/H] [a] "a" indicates enhanced abundances by 0.4dex for the alpha elements 40- 43 F4.2 km/s Vturb [0.00/2.00] Fixed microturbulent velocity 46- 49 F4.2 --- l/H Mixing-length parameter 51- 57 F7.3 mag small Magnitude through the small filter at the star surface 59- 65 F7.3 mag big Magnitude through the big filter at the star surface 69- 73 F5.3 mag beta Hβ index normalized to Vega
Note (1): Sequential designation, added by CDS, made as Seq-Vt-[M/H]a Note (2): Metallicity has the fixed values [+0.5], [+0.5a], [+0.2], [0.0], [0.0a], [-0.5], [-0.5a], [-1.0], [-1.0a], [-1.5], [-1.5a], [-2.0], [-2.0a], [-2.5], [-2.5a], [-4.0a]
Acknowledgements: Fiorella Castelli, castelli(at)
(End) Patricia Vannier [CDS] 16-May-2006
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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