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2008MNRAS.385.1998K - Mon. Not. R. Astron. Soc., 385, 1998-2010 (2008/April-3)
Spectroscopic ages and metallicities of stellar populations: validation of full spectrum fitting.
KOLEVA M., PRUGNIEL P., OCVIRK P., LE BORGNE D. and SOUBIRAN C.
Abstract (from CDS):
We compare three spectral synthesis models for single stellar populations (SSPs): Pegase-HR, Galaxev and Vazdekis/Miles, and we analyse spectra of Galactic clusters whose populations are known from studies of colour-magnitude diagrams (CMD) and spectroscopy of individual stars.
We find the following. (1) The quality of the models critically depends on the stellar library they use, and in particular on its coverage in age, metallicity and surface gravity of the stars. Pegase-HR and Vazdekis/Miles are consistent, while the comparison between Pegase-HR and Bruzual & Charlot shows some systematics reflecting the limitations of the stellar library (STELIB) used to generate the latter models. (2) The two fitting programs are consistent. (3) For globular clusters and M67 spectra, the method restitutes metallicities in agreement with spectroscopy of stars with a precision of 0.14 dex. (4) The spectroscopic ages are very sensitive to the presence of a blue horizontal branch (BHB) or of blue stragglers. A BHB morphology results in a young SSP-equivalent age. Fitting a free amount of blue stars in addition to the SSP model to mimic the BHB improves and stabilizes the fit and restores ages in agreement with CMDs studies. This method is potentially able to disentangle age or BHB effects in extragalactic clusters. Full spectrum fitting is reliable method to derive the parameters of a stellar population.
Abstract Copyright: ©2008 The Authors. Journal compilation © 2008 RAS
Journal keyword(s): techniques: spectroscopic - globular clusters: general - Galaxy: stellar content
Simbad objects: 43
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