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uvby CCD Photometry of the Upper Main Sequence in ω Centauri

Krishna Mukherjee, Barbara J. Anthony-Twarog and Bruce A. Twarog
Publications of the Astronomical Society of the Pacific
Vol. 104, No. 677 (1992 July), pp. 561-573
Stable URL: http://www.jstor.org/stable/40679902
Page Count: 13
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
uvby CCD Photometry of the Upper Main Sequence in ω Centauri
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Abstract

We have obtained and analyzed charge-coupled device (CCD) frames on the uvby system of a field in ω Centauri in order to constrain the intrinsic dispersion of heavy elements among its unevolved stars. Our results from direct measurements on the metallicity using m ₁ and from indirect measures using the color spread in (b—y) near the turnoff imply an intrinsic dispersion in [Fe/H] of about 1 dex, similar to the results of spectroscopic analysis of the evolved stars. The color spread near the turnoff is consistent with little spread in age, though the constraint is weak. The luminosity spread among the subgiants does allow a range of 2X10⁹ yr if the metal-rich stars are also younger. We have independently recovered the variable blue straggler E39 and have discovered an additional bluestraggler candidate. Finally, we note that the variation in c₁ as a function of magnitude for probable upper main-sequence members suggests that previous evolutionary corrections for metal-poor stars may have been overestimated.

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