New grids of ATLAS9 atmospheres*
II. Limb-darkening coefficients for the Strömgren photometric system for A-F stars
1
National Solar Observatory, 950 N. Cherry Ave., Tucson, AZ 85719, USA e-mail: barban@noao.edu
2
Observatoire de Paris-Meudon, 5 place Jules Janssen, 92195 Meudon Cedex, France e-mail: Caroline.Barban@obspm.fr; MarieJo.Goupil@obspm.fr; Claude.VantVeer@obspm.fr
3
Instituto de Astrofisica de Andalucia, CSIC, Apdo. 3004, 18080 Granada, Spain e-mail: garrido@iaa.es
4
Astronomy Unit, School of Mathematical Sciences, Queen Mary, University of London Mile End Road, London E1 4NS, UK e-mail: f.kupka@qmul.ac.uk
5
Institut für Astronomie, Universität Wien, Türkenschanzstraße 17, 1180 Vienna, Austria
6
Department of Astronomy, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106-7215, USA e-mail: ulrike@fafnir.astr.cwru.edu
Corresponding author: C. Barban, Caroline.Barban@obspm.fr
Received:
6
March
2003
Accepted:
16
April
2003
Using up-to-date model atmospheres (Heiter et al. 2002)
with the turbulent convection approach developed by
Canuto et al. (1996, CGM), quadratic,
cubic and square root limb darkening coefficients (LDC) are
calculated with a least square fit method
for the Strömgren photometric system.
This is done for a sample of
solar metallicity models
with effective temperatures
between 6000 and 8500 K and with 
between 2.5 and 4.5.
A comparison is made between these LDC and
the ones computed from model atmospheres
using the classical mixing length prescription with a mixing length parameter
and 
.
For CGM model atmospheres, the law which reproduces better
the model intensity is found to be the square root one for the u band and
the cubic law for the v band. The results are more complex for the b and
y bands depending on the temperature and gravity of the model.
Similar
conclusions are reached for
MLT models. As expected much larger differences are found
between CGM and MLT with .
In a second part,
the weighted limb-darkening integrals, 
, and
their derivatives with respect to temperature and gravity, are then
computed using the best limb-darkening law. These integrals are known to be very important in the context of
photometric mode identification of non-radial pulsating stars.
The effect of convection treatment on these quantities
is discussed and as expected differences in the 
coefficients and derivatives
computed with CGM and MLT are much smaller than differences obtained between
computations with CGM and MLT .
Key words: stars: atmospheres / stars: oscillations / convection
© ESO, 2003