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A New Feature Along the Extended Blue Horizontal Branch of NGC 6752

Y. Momany·G. Piotto·A. Recio-Blanco·L. R. Bedin·S. Cassisi·G. Bono
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Abstract

In this letter we report on the detection of a new feature in the complex structure of the horizontal branch (HB) of the Galactic globular cluster NGC 6752. In the U vs. (U-V) plane, the HB shows a discontinuity (``jump'') at U-V ~= -1.0 (corresponding T_e ~ 23,000 K). This ``second U-jump'' adds to the u-jump identified by Grundahl et al. (1999) in a dozen of clusters at T_e ~ 11,500 K. We show that this new discontinuity might be due to the combination of post zero age HB evolution and diffusion effects. We identify 11 AGB-manque stars. The comparison between post-HB star counts and evolutionary lifetimes, as predicted by canonical stellar models, shows good agreement, at variance with similar estimates for NGC 6752 available in the literature.

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Y. Momany, G. Piotto, A. Recio-Blanco, L. R. Bedin, S. Cassisi, G. Bono. 2002-07-26. A New Feature Along the Extended Blue Horizontal Branch of NGC 6752. https://doi.org/10.1086/343125

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