2008/05/31 by Sarah L. Martell, Graeme H. Smith, Michael M. Briley · 20 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Cluster (spacecraft) #Globular cluster #Index (typography) #Measure (data warehouse) #Spectral index #Spectral line #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/590457
published in Publications of the Astronomical Society of the Pacific 120(870), 839-847 (Institute of Physics) · 8 pages, emulateapj, accepted by PASP
arxiv created 2008/05/31 · openalex publication_date 2008/07/24 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Spectral indices are useful tools for quantifying the strengths of features in moderate-resolution spectra and relating them to intrinsic stellar parameters. This paper focuses on the 4300 Å CH G-band, a classic example of a feature interpreted through use of spectral indices. G-band index definitions, as applied to globular clusters of different metallicity, abound in the literature, and transformations between the various systems, or comparisons between different authors' work, are difficult and not always useful. We present a method for formulating an optimized G-band index, using a large grid of synthetic spectra. To make our new index a reliable measure of carbon abundance, we minimize its dependence on [N/Fe] and simultaneously maximize its sensitivity to [C/Fe]. We present a definition for the new index S 2 ( CH ), along with estimates of the errors inherent in using it for [C/Fe] determination, and conclude that it is valid for use with spectra of bright globular cluster red giants over a large range in , [C/Fe], and [N/Fe].