Globular clusters, Hipparcos, and the age of the galaxy

Globular clusters, Hipparcos, and the age of the galaxy

Neill Reid*

Palomar Observatory, 105-24, California Institute of Technology, Pasadena, CA 91125

Abstract

We discuss the impact of the results from the recent Hipparcos astrometric satellite on distance estimates of galactic globular clusters. Recalibrating the clusters not only implies a relatively small change in the distance to the Large Magellanic Cloud, and hence a rescaling of several estimates of the Hubble constant, but also leads to significantly younger cluster ages. Although the data are not yet conclusive, the results so far point to a likely resolution of the apparent paradox of a universe younger than its constituents, without requiring significant modifications to simple cosmological models.

Footnotes

↵ * e-mail: inr{at}astro.caltech.edu.
This paper was presented at a colloquium entitled “The Age of the Universe, Dark Matter, and Structure Formation,” organized by David N. Schramm, held March 21–23, 1997, sponsored by the National Academy of Sciences at the Beckman Center in Irvine, CA.
ABBREVIATIONS:

LMC,

Large Magellanic Cloud;

Gyr,

gigayear;

CCD,

charge coupled device;

pc,

parsec;

mas,

milliarcsec;

as,

arcsec;

mag,

magnitude;

HST,

Hubble Space Telescope