Distances and Absolute Ages of Galactic Globular Clusters from Hipparcos Parallaxes of Local Subdwarfs

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dc.creatorGratton, R. G.
dc.creatorPecci, F. Fusi
dc.creatorCarretta, E.
dc.creatorClementini, G.
dc.creatorCorsi, C. E.
dc.creatorLattanzi, M. G.
dc.date1997-07-09
dc.date.accessioned2026-07-07T02:23:47Z
dc.date.available2026-07-07T02:23:47Z
dc.descriptionHigh precision trigonometric parallaxes from the HIPPARCOS satellite and accurate metal abundances ([Fe/H], [O/Fe], and [alpha/Fe]) from high resolution spectroscopy for about 30 local subdwarfs have been used to derive distances and ages for a carefully selected sample of nine globular clusters. We find that HIPPARCOS parallaxes are smaller than the corresponding ground-based measurements leading, to a longer distance scale (~ 0.2 mag) and to ages ~ 2.8 Gyr younger. The relation between the zero age horizontal branch (ZAHB) absolute magnitude and metallicity for the nine programme clusters is : Mv(ZAHB) = (0.22 +/- 0.09)([Fe/H]+1.5) + (0.48 +/- 0.04) The corresponding Large Magellanic Cloud distance modulus is (m-M)o=18.61 +/- 0.07. The age of the bona fide old globular clusters (Oosterhoff II and Blue Horizontal Branch) based on the absolute magnitude of the turn-off is: Age = 11.8 (+2.1/-2.5) Gyr The present age of globular clusters does no longer conflict with standard inflationary models for the Universe.
dc.description6 Pages, 2 postscript figures, Latex using venice97.sty. To appear in Proceedings of the "Hipparcos Venice'97 Symposium", ESA SP-402. Text and figures also available via anonymous ftp at ftp://boas3.bo.astro.it/bap/files/ as bap97-16a-*.ps
dc.identifierhttps://arxiv.org/abs/astro-ph/9707107
dc.identifierhttp://arxiv.org/abs/astro-ph/9707107
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/11382
dc.subjectAstrophysics
dc.titleDistances and Absolute Ages of Galactic Globular Clusters from Hipparcos Parallaxes of Local Subdwarfs
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