Analysing observed star cluster SEDs with evolutionary synthesis models: systematic uncertainties

P. Anders*, N. Bissantz, U. Fritze-V. Alvensleben, R. De Grijs

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

121 Citations (Scopus)


We discuss the systematic uncertainties inherent to analyses of observed (broad-band) spectral energy distributions (SEDs) of star clusters with evolutionary synthesis models. We investigate the effects caused by restricting oneself to a limited number of available passbands, choices of various passband combinations, finite observational errors, non-continuous model input parameter values, and restrictions in parameter space allowed during analysis. Starting from a complete set of UBVRIJH passbands (respectively, their Hubble Space Telescope/WFPC2 equivalents) we investigate to what extent clusters with different combinations of age, metallicity, internal extinction and mass can or cannot be disentangled in the various evolutionary stages throughout their lifetimes and what are the most useful passbands required to resolve the ambiguities. We find the U and B bands to be of the highest significance, while the V band and near-infrared data provide additional constraints. A code is presented that makes use of luminosities of a star cluster system in all of the possibly available passbands, and tries to find ranges of allowed age-metallicity-extinction-mass combinations for individual members of star cluster systems. Numerous tests and examples are presented. We show the importance of good photometric accuracies and of determining the cluster parameters independently without any prior assumptions.

Original languageEnglish
Pages (from-to)196-212
Number of pages17
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Publication statusPublished - 1 Jan 2004
Externally publishedYes


  • galaxies: evolution
  • galaxies: star clusters
  • globular clusters: general
  • methods: data analysis
  • open clusters and associations: general


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