Issue |
A&A
Volume 450, Number 3, May II 2006
|
|
---|---|---|
Page(s) | 979 - 992 | |
Section | Galactic structure, stellar clusters, and populations | |
DOI | https://doi.org/10.1051/0004-6361:20053865 | |
Published online | 19 April 2006 |
Surface-brightness fluctuations in stellar populations
IAC-star models for the optical and near-IR wavelengths
1
Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611, USA e-mail: amarin@astro.ufl.edu
2
Departamento de Astrofísica, Universidad de La Laguna; and Instituto de Astrofísica de Canarias, Calle vía Láctea s/n, 38200 La Laguna, Tenerife, Spain e-mail: antapaj@iac.es
Received:
20
July
2005
Accepted:
14
December
2005
Aims.A new theoretical calibration of surface-brightness fluctuations (SBF) for single age, single metallicity stellar populations is presented for the optical and near-IR broad-band filters, as well as for the HST WFPC2 and ACS filters.
Methods.The IAC-star code is used. Two Padua and the Teramo stellar evolution
libraries have been considered.
A set of single-burst stellar populations (SSP) with a wide range of ages
(3 Gy-15 Gy) and metallicities (Z = 0.0001-0.03) have been computed using
each one of the three considered stellar evolution libraries.
For each SSP, color indexes and SBF magnitudes are given
for the filters U, B, V, R, I, J, H, K, ,
,
,
,
and
, and for the first time,
an uncertainty has been estimated for the SBF theoretical calibration.
Results.Although some differences might be addressed, the Padua and Teramo
stellar evolution libraries provide comparable SBF results.
A detailed comparison of the present SBF calibrations with both previous
calibrations and observational data is also presented.
Comparing the different models with observational data, Padua based models
reproduce fairly well the optical data for globular clusters,
while Teramo based models fits both optical galaxies and globular clusters
data, as well. In the near-IR wavelengths, the Teramo based models
provide the only SBF theoretical calibration to date
able to properly reproduce the observational data for
superclusters, with intermediate-to-low metallicity.
As a conclusion, Teramo based models work better than any other calibration
reproducing observational data for the near-IR wavelengths. Furthermore, the
age-metallicity degeneracy is broken for low metallicity () stellar
populations. Finally,
a clear relation between the B SBF absolute magnitude of a stellar population
and its metallicity is found for intermediate to old populations, so
the B-band fluctuation magnitude is proposed as a metallicity tracer.
The present theoretical calibration shows that the analysis of SBF
provides a very powerful tool in the study and characterization of
unresolved stellar populations.
© ESO, 2006
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