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Date and Time of the Query: 2019-06-16 T08:59:05 PDT
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For refcode 2009MNRAS.392..691C:
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Copyright by Royal Astronomical Society. 2009MNRAS.392..691C An optimized H{beta} index for disentangling stellar population ages Cervantes, J. L.; Vazdekis, A. Abstract. We have defined a new H{beta} absorption index definition, H{beta}_o_, which has been optimized as an age indicator for old and intermediate age stellar populations. Rather than using stellar spectra, we employed for this purpose a library of stellar population spectral energy distributions of different ages and metallicities at moderately high resolution. H{beta}_o_ provides us with improved abilities for lifting the age-metallicity degeneracy affecting the standard H{beta} Lick index definition. The new index, which has also been optimized against photon noise and velocity dispersion, is fully characterized with wavelength shift, spectrum shape, dust extinction and [{alpha}/Fe] abundance ratio effects. H{beta}_o_ requires spectra of similar qualities as those commonly used for measuring the standard H{beta} Lick index definition. Aiming at illustrating the use and capabilities of H{beta}_o_ as an age indicator we apply it to Milky Way globular clusters and to a well selected sample of early-type galaxies covering a wide range in mass. The results shown here are particularly useful for applying this index and understand the involved uncertainties. Key words: globular clusters: general, galaxies: abundances, galaxies: elliptical and lenticular, cD, galaxies: stellar content
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