Issue |
A&A
Volume 485, Number 3, July III 2008
|
|
---|---|---|
Page(s) | 823 - 835 | |
Section | Stellar atmospheres | |
DOI | https://doi.org/10.1051/0004-6361:20078923 | |
Published online | 06 May 2008 |
Probing Atlas model atmospheres at high spectral resolution
Stellar synthesis and reference template validation
1
INAOE - Instituto Nacional de Astrofísica, Óptica y Electrónica, Luis Enrique Erro 1, 72840 Tonantzintla, Puebla, Mexico e-mail: [ebertone;mchavez;lino]@inaoep.mx
2
INAF - Osservatorio Astronomico di Bologna, Via Ranzani 1, 40127 Bologna, Italy e-mail: buzzoni@bo.astro.it
Received:
12
October
2007
Accepted:
21
April
2008
Aims. The fast improvement of spectroscopic observations makes mandatory a
strong effort on the theoretical side to better reproduce the spectral
energy distribution (SED) of stars at high spectral resolution. In this
regard, relying on the Kurucz Atlas/Synthe original codes
we computed the Bluered library, consisting of 832 synthetic SED of stars, that cover a large parameter space at very
high spectral resolution () along the 3500-7000 Å wavelength
range.
Methods. Bluered synthetic spectra have been used to assess in finer detail the intrinsic reliability and the performance limits of the Atlas theoretical framework. The continuum-normalized spectra of the Sun, Arcturus, and Vega, plus a selected list of 45 bright stars with high-quality SEDs from the Prugniel & Soubiran Elodie catalog, form our sample designed to probe the global properties of synthetic spectra across the entire range of H-R parameters.
Results. Atlas models display a better fitting performance with
increasing stellar temperature. High-resolution spectra of Vega, the Sun,
and Arcturus have been reproduced at , respectively, within a
0.7%, 4.5%, and 8.8% relative scatter in residual flux. In all the
three cases, the residual flux distribution shows a significant asymmetry
(skewness parameter
, respectively),
which neatly confirms an overall “excess” of theoretical line blanketing.
For the Sun, this apparent discrepancy is alleviated, but not recovered,
by a systematic decrease (-40%) of the line oscillator strengths,
, especially referring to iron transitions. Definitely, a straight
“astrophysical” determination of
for each individual atomic
transition has to be devised to overcome the problem. By neglecting
overblanketing effects in theoretical models when fitting high-resolution
continuum-normalized spectra of real stars, we lead to a systematically
warmer effective temperature (between +80 and +300 K for the solar fit)
and a slightly poorer metal content.
Key words: Sun: atmosphere / stars: atmospheres / stars: individual: Arcturus / stars: individual: Vega / stars: fundamental parameters / line: profiles
© ESO, 2008
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