ﻻ يوجد ملخص باللغة العربية
Current stellar population models have arguably the largest uncertainties in the near-IR wavelength range, partly due to a lack of large and well calibrated empirical spectral libraries. In this paper we present a project, which aim it is to provide the first library of luminosity weighted integrated near-IR spectra of globular clusters to be used to test the current stellar population models and serve as calibrators for the future ones. Our pilot study presents spatially integrated K-band spectra of three old (>10 Gyr) and metal poor ([Fe/H]~-1.4), and three intermediate age (1-2 Gyr) and more metal rich ([Fe/H]~-0.4) globular clusters in the LMC. We measured the line strengths of the Na I, Ca I and 12CO(2-0) absorption features. The Na I index decreases with the increasing age and decreasing metallicity of the clusters. The Dco index, used to measure the 12CO(2-0) line strength, is significantly reduced by the presence of carbon-rich TP-AGB stars in the globular clusters with age ~1 Gyr. This is in contradiction with the predictions of the stellar population models of Maraston (2005). We find that this disagreement is due to the different CO absorption strength of carbon-rich Milky Way TP-AGB stars used in the models and the LMC carbon stars in our sample. For globular clusters with age >2 Gyr we find Dco index measurements consistent with the model predictions.
We present Hubble Space Telescope ACS deep photometry of the intermediate-age globular cluster NGC 1783 in the Large Magellanic Cloud. By using this photometric dataset, we have determined the degree of ellipticity of the cluster ($epsilon$=0.14$pm$0
We present flux-calibrated integrated spectra in the optical range (3700-6800 AA) obtained at Complejo Astronomico El Leoncito (CASLEO, Argentina) for a sample of 10 concentrated star clusters belonging to the Large Magellanic Cloud (LMC). No previou
(Abridged) In the recent controversy about the role of TP-AGB stars in evolutionary population synthesis (EPS) models of galaxies, one particular aspect is puzzling: TP-AGB models aimed at reproducing the lifetimes and integrated fluxes of the TP-AGB
We present structural parameters for the seven intermediate-age and old star clusters NGC121, Lindsay 1, Kron 3, NGC339, NGC416, Lindsay 38, and NGC419 in the Small Magellanic Cloud. We fit King profiles and Elson, Fall, and Freeman profiles to both
We present results obtained from spectroscopic observations of red giants located in the fields of the Large Magellanic Cloud (LMC) globular clusters (GCs) NGC 1928 and NGC 1939. We used the GMOS and AAOmega+2dF spectrographs to obtain spectra centre