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 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 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 1995A&A...293..446S) (MD95) and with the
empirical relations Teff-Hβ given by Alonso et al.
(1996A&A...313..873A 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:
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FileName Lrecl Records Explanations
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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.
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See also:
J/A+A/333/231 : O-M stars model atmospheres (Bessell+ 1998)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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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(FeSun)] (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
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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]
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Acknowledgements: Fiorella Castelli, castelli(at)oats.inaf.it
(End) Patricia Vannier [CDS] 16-May-2006