Ages of Large Magellanic Cloud Star Clusters with Gemini Multi-Object Spectrograph Integrated Spectroscopy: Systematic Comparison of Available Tools

Abstract

We present the first systematic analysis comparing the ages, reddening, and radial velocities of star clusters using two widely used tools: STARLIGHT and Analyzer of Spectra for Age Determination (A.S.A.D). Both tools utilize the full integrated spectrum fitting technique but they use different approaches in calculating the parameters. We find that there is a good agreement between the parameters derived by the two tools and confirm that both tools provide consistent results with the literature parameters obtained from resolved photometry. We note that for optimal age and reddening estimates, observed integrated spectra should have signal-to-noise ratio (S/N) > 10when using A.S.A.D and the combination of the single stellar populations should be added linearly (not using logarithmic values) when using STARLIGHT . We also show that the deviation of the radial velocity estimates between the two tools depends on the S/N of the observed integrated spectrum and demonstrate that when varying the metallicity, the age estimates of STARLIGHT are not affected significantly, while the results of A.S.A.D are generally underestimated. As more observational data become available through modern instruments, the strengths and limitations of each available automated tool need to be taken in consideration when interpreting their results.