Surface-brightness fluctuations in stellar populations

Free access article

Issue		A&A Volume 450, Number 3, May II 2006


Page(s)		979 - 992
Section		Galactic structure, stellar clusters, and populations
DOI		http://dx.doi.org/10.1051/0004-6361:20053865

A&A 450, 979-992 (2006)
DOI: 10.1051/0004-6361:20053865

IAC-star models for the optical and near-IR wavelengths

A. Marín-Franch¹ and A. Aparicio²

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 )

Abstract
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, ${\it F218W}$ , ${\it F336W}$ , ${\it F439W}$ , ${\it F450W}$ , ${\it F555W}$ and ${\it F814W}$ , 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 ( $Z\leq0.0037$ ) 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.

Key words: galaxies: distances and redshifts -- galaxies: elliptical and lenticular, cD -- galaxies: fundamental parameters -- galaxies: star clusters -- galaxies: stellar content

SIMBAD Objects

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.