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Spectroscopic ages and metallicities of stellar populations: validation of full spectrum fitting
- Source :
- Monthly Notices of the Royal Astronomical Society, Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P-Oxford Open Option A, 2008, 385 (4), pp.1998-2010, Monthly Notices of the Royal Astronomical Society, 2008, 385, pp.1998-2010. ⟨10.1111/j.1365-2966.2008.12908.x⟩, Monthly Notices of the Royal Astronomical Society, 2008, 385 (4), pp.1998-2010
- Publication Year :
- 2008
- Publisher :
- Oxford University Press (OUP), 2008.
-
Abstract
- Fitting whole spectra at intermediate spectral resolution (R = 1000 -- 3000), to derive physical properties of stellar populations, appears as an optimized alternative to methods based on spectrophotometric indices: it uses all the redundant information contained in the signal. This paper addresses the validation of the method and it investigates the quality of the population models together with the reliability of the fitting procedures. We are using two algorithms: STECKMAP, a non-parametric regularized program and NBURSTS a parametric non-linear minimization. We compare three spectral synthesis models for single stellar populations: Pegase-HR, Galaxev (BC03) and Vazdekis/Miles, and we analyse spectra of Galactic clusters whose populations are known from studies of color-magnitude diagrams (CMD) and spectroscopy of individual stars. We find that: (1) The quality of the models critically depends on the stellar library they use. Pegase-HR and Vazdekis/Miles are consistent, while the comparison between Pegase-HR and BC03 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 within 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.<br />Comment: accepted in MNRAS; Full version available at http://www-obs.univ-lyon1.fr/labo/perso/prugniel/mina/koleva.pdf
- Subjects :
- FOS: Physical sciences
Astrophysics
[SDU.ASTR] Sciences of the Universe [physics]/Astrophysics [astro-ph]
01 natural sciences
Blue straggler
Spectral line
[PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]
Galaxy groups and clusters
0103 physical sciences
Spectral resolution
Spectroscopy
010303 astronomy & astrophysics
Physics
Galaxy: stellar content
(Galaxy:) globular clusters: general
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph]
010308 nuclear & particles physics
Astrophysics (astro-ph)
Astronomy and Astrophysics
Horizontal branch
Stars
[PHYS.ASTR.CO] Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]
Space and Planetary Science
Globular cluster
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
techniques: spectroscopic
Subjects
Details
- ISSN :
- 13652966 and 00358711
- Volume :
- 385
- Database :
- OpenAIRE
- Journal :
- Monthly Notices of the Royal Astronomical Society
- Accession number :
- edsair.doi.dedup.....924ec6e6e1b6ec49ed3297e62818e9a6