1996/10/29 by Ricardo P. Schiavon, R. P. Schiavon, B. Barbuy +5 · 6 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Scientific Research and Discoveries #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/303907
9 pages, (TeX file) + 7 Figures in Postscript format. Accepted for publication in The Astrophysical Journal
arxiv created 1996/10/29 · openalex publication_date 1997/04/20 · arxiv updated 2009/12/01 · openalex created_date 2019/06/27 · openalex updated_date 2026/07/31
The Na I near-infrared feature has been used to indicate the dwarf/giant population in composite systems, but its interpretation is still an issue of contention. In order to try to understand the behavior of this controversial feature, we study the spectra of cool stars by means of both observed and synthetic spectra. We conclude that the Na I infrared feature can be used as a dwarf/giant indicator. We propose a modified definition of the Na I index by defining a red continuum at 8234 Å and by measuring the equivalent width in the range 8172-8197 Å, avoiding the region at λ > 8197 Å, which contains V I, Zr I, Fe I, and TiO lines.