*Astron. Astrophys. 363, 1081-1190 (2000)*
## A new non-linear limb-darkening law for LTE stellar atmosphere models
### Calculations for at several
surface gravities ^{*}
**
A. Claret
**
Instituto de Astrofísica de Andalucía, CSIC, Apartado 3004, 18080 Granada, Spain
*Received 21 July 2000 / Accepted 15 September 2000*
**Abstract**
A new non-linear limb-darkening law, based on the Least-Squares
Method (LSM), is presented. This law is able to describe the intensity
distribution much more accurately than any of the old ones given that
the differences I(model)-I(fitting) are of some order of magnitude
smaller than those derived from other approximations. This new law
shows several advantages: it represents well the intensity
distribution, the flux is conserved with high accuracy and it permits
the use of a single law for the whole HR Diagram since the
bi-parametric laws are only marginally valid in certain ranges of
effective temperatures. The limb-darkening coefficients are computed
for the 12 commonly used photometric bands
. Bolometric and monochromatic
calculations are also available. The computations are presented for 19
metallicities ranging from 10^{-5} up to 10^{+1} solar
abundances, with log g varying between 0 and 5.0 and effective
temperatures between 2000 K-50000 K. Results for microturbulent
velocities of 0, 1, 2, 4, 8 km/s are also available. With this set of
data it was possible to investigate, for the first time, the influence
of such parameters in the limb-darkening. Limb-brightening, instead of
limb-darkening, was detected for some models.
It is shown that the limb-darkening coefficients derived using the
Flux Conservation Method (FCM) do not describe very well the intensity
distribution, mainly near the border of the disk. On the contrary, the
present coefficients, based on the LSM, represent very well the
function I(*µ*) at any part of the disk for any filter or
wavelength, log g, effective temperature, metallicity and
microturbulent velocity.
The results are presented in 46 tables for the 12 filters
(bolometric) and can be retrieved from the CDS. Due to the size of the
remaining tables, mainly the monochromatic, these are available only
on request (CD ROMs).
**Key words:** stars:
atmospheres
stars: binaries: eclipsing
* Tables 1-47 are available in electronic form at the CDS via anonymous ftp to ftp://cdsarc.u-strasbg.fr/pub/cats/J/A+A/363/1081 (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/363/1081 . Additional data are available on CD ROMs upon request. See online edition of A&A for Fig. 1, Fig. 4, Fig. 6 and Fig. 7 are only available here in the online version.
*Send offprint requests to:* claret@iaa.es
This article contains no SIMBAD objects.
### Contents
© European Southern Observatory (ESO) 2000
Online publication: December 5, 2000
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