2010/03/12 by B. J. Anthony-Twarog, Barbara J. Anthony-Twarog, Constantine P. Deliyannis +7 · 2 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Blue straggler #Cluster (spacecraft) #Hertzsprung–Russell diagram #Metallicity #Open cluster #Photometry (optics) #Physics #Radial velocity #Star cluster #Stars #Stellar evolution #Stellar, planetary, and galactic studies #astro-ph.GA
paper · pdf · doi:10.1088/0004-6256/139/5/2034
5 Tables, 9 figures, 45 pages
arxiv created 2010/03/12 · openalex publication_date 2010/04/08 · arxiv updated 2015/05/18 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
High-dispersion spectra of 89 potential members of the old, super-metal-rich open cluster, NGC 6253, have been obtained with the HYDRA multi-object spectrograph. Based upon radial-velocity measurements alone, 47 stars at the turnoff of the cluster color–magnitude diagram (CMD) and 18 giants are identified as potential members. Five turnoff stars exhibit evidence of binarity while proper-motion data eliminate two of the dwarfs as members. The mean cluster radial velocity from probable single-star members is −29.4 ± 1.3 km s −1 (sd). A discussion of the current estimates for the cluster reddening, derived independently of potential issues with the BV cluster photometry, lead to an adopted reddening of E ( B − V ) = 0.22 ± 0.04. From equivalent width analyses of 38 probable single-star members near the CMD turnoff, the weighted average abundances are found to be [Fe/H] = +0.43 ± 0.01, [Ni/H] = +0.53 ± 0.02, and [Si/H] = +0.43 0.03 0.04 , where the errors refer to the standard errors of the weighted mean. Weak evidence is found for a possible decline in metallicity with increasing luminosity among stars at the turnoff. We discuss the possibility that our turnoff stars have been affected by microscopic diffusion. For 15 probable single-star members among the giants, spectrum synthesis leads to abundances of +0.46 0.02 0.03 for [Fe/H]. While NGC 6253 is less than half the age of NGC 6791, it is at least as metal-rich and, within the uncertainties, exhibits the same general abundance pattern as that typified by super-metal-rich dwarfs of the galactic bulge.