On the Age and Metallicity Estimation of Spiral Galaxies Using Optical and Near‐Infrared Photometry

2006/05/31 by Hyun‐Chul Lee, Hyun-chul Lee, Guy Worthey +4 · 6 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Galaxies: Formation, Evolution, Phenomena #Galaxy #Metallicity #Photometry (optics) #Physics #Population #Spiral galaxy #Star formation #Stars #Stellar population #Stellar, planetary, and galactic studies #astro-ph

paper · pdf · doi:10.1086/518855

published as Astrophys.J.664:215-225,2007 · 33 pages, 15 figures. Accepted to ApJ (Apr 2007). The major surgery was Fig. 14

arxiv created 2007/04/13 · openalex publication_date 2007/07/10 · arxiv updated 2009/12/01 · openalex created_date 2020/11/23 · openalex updated_date 2026/08/05

Abstract

In integrated light, some color-color diagrams that use optical and near-infrared photometry show surprisingly orthogonal grids as age and metallicity are varied, and they are coming into common usage for estimating the average age and metallicity of spiral galaxies. In this paper we reconstruct these composite grids using simple stellar population models from several different groups convolved with some plausible functional forms of star formation histories at fixed metallicity. We find that the youngest populations present ( t < 2 Gyr) dominate the light, and because of their presence the age-metallicity degeneracy can be partially broken with broadband colors, unlike older populations. The scatter among simple stellar population models by different authors is, however, large at ages t < 2 Gyr. The dominant uncertainties in stellar population models arise from convective core overshoot assumptions and the treatment of the thermally pulsing asymptotic giant branch phase and helium abundance may play a significant role at higher metallicities. Real spiral galaxies are unlikely to have smooth, exponential star formation histories, and burstiness will cause a partial reversion to the single-burst case, which has even larger model-to-model scatter. Finally, it is emphasized that the current composite stellar population models need some implementation of chemical enrichment histories for the proper analysis of the observational data.

Citations

• The Initial Mass Function of Stars: Evidence for Uniformity in Variable Systems
• Did most present-day spirals form during the last 8 Gyr?
• Toward Better Age Estimates for Stellar Populations: The Y 2 Isochrones for Solar Mixture
• Y 2 Isochrones with an Improved Core Overshoot Treatment
• The Globular Cluster NGC 1978 in the Large Magellanic Cloud
• Physical parameters of 15 intermediate-age LMC clusters from modelling of HST colour–magnitude diagrams
• Evidence for TP‐AGB Stars in High‐Redshift Galaxies, and Their Effect on Deriving Stellar Population Parameters
• Evolutionary tracks and isochrones for low- and intermediate-mass stars: From 0.15 to 7 M_\odot, and from Z=0.0004 to 0.03
• Galactic Stellar and Substellar Initial Mass Function
• The Adequacy of Stellar Evolution Models for the Interpretation of the Color-Magnitude Diagrams of Resolved Stellar Populations

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• THE PROPAGATION OF UNCERTAINTIES IN STELLAR POPULATION SYNTHESIS MODELING. III. MODEL CALIBRATION, COMPARISON, AND EVALUATION
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