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arXiv · 0806.0581

A new stellar library in the region of the CO index at 2.3 $\mu$m. New index definition and empirical fitting functions

E. Mármol-Queraltó·N. Cardiel·A. J. Cenarro·A. Vazdekis·J. Gorgas·S. Pedraz·R. F. Peletier·P. Sánchez-Blázquez
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Abstract

Context: The analysis of unresolved stellar populations demands evolutionary synthesis models with realistic physical ingredients and extended wavelength coverage. Aims: To obtain a quantitative description of the first CO bandhead at 2.3 $\mu$m, to allow stellar population models to provide improved predictions in this wavelength range. Methods: We have observed a new stellar library with a better coverage of the stellar atmospheric parameter space than preceding works. We have performed a detailed analysis of the robustness of previous CO index definitions with spectral resolution, wavelength calibration, signal-to-noise ratio, and flux calibration. Results: We define a new line-strength index for the first CO bandhead at 2.3 $\mu$m, D$_{\rm CO}$, better suited for stellar population studies than previous index definitions. We compute empirical fitting functions for the CO feature as a function of the stellar parameters (T$_{\rm eff}$, $\log g$ and [Fe/H]), showing a detailed quantitative metallicity dependence.

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E. Mármol-Queraltó, N. Cardiel, A. J. Cenarro, A. Vazdekis, J. Gorgas, S. Pedraz, R. F. Peletier, P. Sánchez-Blázquez. 2008-06-03. A new stellar library in the region of the CO index at 2.3 $\mu$m. New index definition and empirical fitting functions. https://doi.org/10.1051/0004-6361:200810044

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