Published in
American Astronomical Society, Astrophysical Journal, 1(576), p. L65-L68, 2002
DOI: 10.1086/343125
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A New Feature along the Extended Blue Horizontal Branch of NGC 6752
,
Alejandra Recio-Blanco,
Luigi R. Bedin ,
Santi Cassisi ,
and Giuseppe Bono,
G.
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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 versus (U-V)-plane, the HB shows a discontinuity ("jump") at U-V -1.0 (corresponding Teff ~ 23,000 K). This "second U-jump" adds to the u-jump identified by F. Grundahl et al. in a dozen clusters at Teff ~ 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 asymptotic giant branch manqué 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.