EVIDENCE FOR INTERMEDIATE-AGE STELLAR POPULATIONS IN EARLY-TYPE GALAXIES FROM K -BAND SPECTROSCOPY
| Autor: | Harald Kuntschner, Nicolás Cardiel, Scott Trager, Javier Gorgas, David R. Silva, A. Vazdekis, Reynier Peletier, E. Mármol-Queraltó, A. J. Cenarro, Patricia Sanchez-Blazquez |
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| Přispěvatelé: | Kapteyn Astronomical Institute, Astronomy |
| Rok vydání: | 2009 |
| Předmět: |
Astrofísica
Cosmology and Nongalactic Astrophysics (astro-ph.CO) Metallicity Population MU-M FOS: Physical sciences Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics S0 GALAXIES cD Base (group theory) ELLIPTIC GALAXIES GLOBULAR-CLUSTERS galaxies: formation NITROGEN ABUNDANCES Astrophysics::Solar and Stellar Astrophysics galaxies: elliptical and lenticular Fornax Cluster education Spectroscopy LOW-DENSITY ENVIRONMENTS Astrophysics::Galaxy Astrophysics CALIBRATION Physics education.field_of_study Star formation Física atmosférica Astronomy and Astrophysics FORNAX CLUSTER Galaxy Astronomía Stars galaxies: clusters: general Space and Planetary Science galaxies: elliptical and lenticular cD galaxies: stellar content Astrophysics::Earth and Planetary Astrophysics galaxies: evolution METALLICITY Astrophysics - Cosmology and Nongalactic Astrophysics LICK INDEXES |
| Zdroj: | Astrophysical Journal Letters, 705(2), L199-L203. IOP PUBLISHING LTD E-Prints Complutense. Archivo Institucional de la UCM instname E-Prints Complutense: Archivo Institucional de la UCM Universidad Complutense de Madrid |
| ISSN: | 1538-4357 0004-637X 2041-8213 |
| DOI: | 10.1088/0004-637x/705/2/l199 |
| Popis: | The study of stellar populations in early-type galaxies in different environments is a powerful tool for constraining their star formation histories. This study has been traditionally restricted to the optical range, where dwarfs around the turn-off and stars at the base of the RGB dominate the integrated light at all ages. The near-infrared spectral range is especially interesting since in the presence of an intermediate-age population, AGB stars are the main contributors. In this letter, we measure the near-infrared indices NaI and D$_{\rm CO}$ for a sample of 12 early-type galaxies in low density environments and compare them with the Fornax galaxy sample presented by Silva et al. (2008). The analysis of these indices in combination with Lick/IDS indices in the optical range reveals i) the NaI index is a metallicity indicator as good as C4668 in the optical range, and ii) D$_{\rm CO}$ is a tracer of intermediate-age stellar populations. We find that low-mass galaxies in low density environments show higher NaI and D$_{\rm CO}$ than those located in Fornax cluster, which points towards a late stage of star formation for the galaxies in less dense environments, in agreement with results from other studies using independent methods. 7 pages, 3 figures, accepted for publication in ApJL |
| Databáze: | OpenAIRE |
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