A Search for Stars of Very Low Metal Abundance. IV. uvbyCa Observations of Metal-Weak Candidates from the Northern HK Survey
Barbara J. Anthony-Twarog, Ata Sarajedini, Timothy C. Beers, Bruce A. Twarog
Abstract
CCD photometry on the uvbyCa system has been obtained for 521 candidate metal-poor stars from the northern hemisphere HK survey of Beers and colleagues. Reddening corrections, classifications of stars by luminosity class, and the derivation of metal abundances based on Stromgren indices m1 and hk are described and presented, along with preliminary spectroscopic estimates of abundance. A number of extremely metal-poor stars with [Fe/H] less than or equal to -2.50 are identified.
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