A Lower Limit on the Age of the Universe

  title={A Lower Limit on the Age of the Universe},
  author={Brian Chaboyer and Pierre. Demarque and Peter J. Kernan and Lawrence Krauss},
  pages={957 - 961}
A detailed numerical study was designed and conducted to estimate the absolute age and the uncertainty in age (with confidence limits) of the oldest globular clusters in our galaxy, and hence to put a robust lower bound on the age of the universe. Estimates of the uncertainty range and distribution in the input parameters of stellar evolution codes were used to produce 1000 Monte Carlo realizations of stellar isochrones, which were then used to derive ages for the 17 oldest globular clusters. A… 
Theoretical Uncertainties in the Subgiant Mass-Age Relation and the Absolute Age of ω Centauri
The theoretical uncertainties in the calibration of the relationship between the subgiant mass and age in metal-poor stars are investigated using a Monte Carlo approach. Assuming that the mass and
Constraint on the cosmic age from the solar r-process abundances
The cosmic age is an important physical quantity in cosmology. Based on the radiometric method, a reliable lower limit of the cosmic age is derived to be Gyr, using the r-process abundances inferred
The Age of Globular Clusters in Light of Hipparcos: Resolving the Age Problem?
We review five independent techniques that are used to set the distance scale to globular clusters, including subdwarf main-sequence fitting utilizing the recent Hipparcos parallax catalog. These
New globular cluster age estimates and constraints on the cosmic equation of state and the matter density of the universe
New estimates of globular cluster distances, combined with revised ranges for input parameters in stellar evolution codes and recent estimates of the earliest redshift of cluster formation allow us
Status of Cosmological Parameters
The cosmological parameters that I will discuss are the Hubble parameter H 0 ≡100h km s-1 Mpc-1, the age of the universe t 0, the average density Ω0, and the cosmological constant Λ. The most
Distances and ages of NGC 6397, NGC 6752 and 47 Tuc
New improved distances and absolute ages for the Galactic globular clusters NGC 6397, NGC 6752, and 47 Tuc are obtained using the Main Sequence Fitting Method. We derived accurate estimates of
Theoretical Uncertainties in Red Giant Branch Evolution: The Red Giant Branch Bump
A Monte Carlo simulation exploring uncertainties in standard stellar evolution theory on the red giant branch of metal-poor globular clusters has been conducted. Confidence limits are derived on the
Absolute Ages and Distances of 22 GCs using Monte Carlo Main-Sequence Fitting
The recent Gaia Data Release 1 of stellar parallaxes provides ample opportunity to find metal-poor main-sequence stars with precise parallaxes. We select 21 such stars with parallax uncertainties


Absolute ages of globular clusters and the age of the universe
The main sequence turnoff luminosity is the best stellar `clock' which can be used to determine the absolute ages of globular clusters. This is due to the fact that it is generally assumed that the
The horizontal-branch stars in globular clusters. 2: The second parameter phenomenon
The results support the hypothesis of Searle & Zinn that the inner halo is more uniform in age and is older in the mean than the outer halo, and it is estimated to be approximately 2 Gyr.
Stellar models with microscopic diffusion and rotational mixing 2.: Application to open clusters
Stellar models with masses ranging from 05.5 to 1.3 solar mass were constructed for comparison with young cluster observations of Li and of rotation velocities. The amount of Li depletion in cool
Oxygen-enhanced Models for Globular Cluster Stars. II. Isochrones and Luminosity Functions
Isochrones and luminosity functions (LFs) on the BV photometric system have been constructed for ages from 10 to 18 Gyr for each of the seven values of [Fe/H] = -2.26, -2.03, -1.78, - 1.66, -1.48,
The opal equation of state and low-metallicity isochrones
The Yale stellar evolution code has been modified to use the OPAL equation of state tables (Rogers 1994). Stellar models and isochrones were constructed for low metallicity systems ($-2.8 \le [Fe/H]
Li-7 abundances in halo stars: Testing stellar evolution models and the primordial Li-7 abundance
A large number of stellar evolution models with (Fe/H) = -2.3 and -3.3 have been calculated in order to determine the primordial Li-7 abundance and to test current stellar evolution models by a
Observational Tests of Cosmological Inflation
I. Inflation Theory.- Fundamental Arguments for Inflation.- Predictions of Inflation.- Classicality of Density Perturbations in the Early Universe.- The Influence of Non-Linear Density Fluctuations
Stellar oxygen abundances. I: A resolution to the 7774 Å O I abundance discrepancy
We investigate the discrepancy between [O/Fe] ratios of metal-poor stars derived from the 7774 A O I triplet and [O/Fe] ratios determined from other oxygen lines. We propose a possible resolution to
Chemical composition and atmospheric parameters of metal-poor halo stars
The abundance of oxygen in 9 metal-poor stars is derived from high resolution observations of OH lines in the spectral region 3138-3155 A. The same spectra were previously used to determine the