Related papers: The Age of the Universe
A precise measurement of the curvature of the Universe is of primeval importance for cosmology since it could not only confirm the paradigm of primordial inflation but also help in discriminating between different early Universe scenarios.…
Globular clusters are ancient stellar populations with no star formation or core-collapse supernovae. Several lines of evidence suggest that globular clusters are rich in planets. If so, and if advanced civilizations can develop there, then…
The properties of old globular cluster systems in galaxy halos are used to infer quantitative constraints on aspects of generic star (cluster) formation. First, the spatial distribution of globulars in three large galaxies, together with…
I propose and apply a method for deriving ages of the metal-poor globular clusters (GCs) in a distance-independent way, which is based on age indicator related to the main sequence in the two-color diagrams with U-B index. Age of the…
Spectra of galaxies contain an enormous amount of information about the relative mixture of ages and metallicities of constituent stars. We present a comprehensive study designed to extract the maximum information from spectra of data…
In the last decade we have come to realize that the traditional classification of stellar clusters into open and globular clusters cannot be easily extended beyond the realm of the Milky Way, and that even for our Galaxy it is not fully…
New information has recently become available on the fundamental plane for various samples of early-type galaxies with redshift up to 1.3, both in clusters and in the field. This information is reviewed and clues are derived on the…
This review covers age-dating methods applied to young stellar populations in starburst galaxies with ages of 10^8 yr and less. First, recent advances in stellar modeling, both for the interior and the atmospheres, are discussed and…
We address the question how accurately stellar ages can be determined by stellar evolution theory. We select the star with the best observational material available - our Sun. We determine the solar age by fitting solar evolution models to…
Deep CCD photometry down to V=24.5 is presented for the old Magellanic Globular cluster NGC 2257. The main result cna be summarized as follows: i) the RGB Bump has been detected at V=18.7+-0.1, and is compatible with determination of this…
Globular Clusters (GCs) in the Milky Way are the primary laboratories for establishing the ages of the oldest stellar populations and for measuring the color-magnitude relation of stars. In infrared (IR) color-magnitude diagrams (CMDs), the…
We present an exploration of the significance of Carbon/Oxygen phase separation in white dwarf stars in the context of self-consistent evolutionary calculations. Because phase separation can potentially increase the calculated ages of the…
Current observations of the fraction of dark energy and a lower limit on its tension, coupled with an assumption of the non-convexity of the dark energy potential, are used to derive a lower limit of 26 billion years for the future age of…
We present our new, fully-automated method to detect and measure the ages of star clusters in nearby galaxies, where individual stars can be resolved. The method relies purely on statistical analysis of observations and Monte-Carlo…
A new expression to the total age of the Universe is derived in terms of the average deceleration parameter. This kinematic result holds regardless of the curvature of the universe as well as of the underlying gravity theory. It remains…
Recent studies have reported a non evolution of galaxy ages at redshifts higher than $z\sim$ 2.5, as well as galaxies older than the Universe. In this work, a sample of galaxies from JWST and HST was analysed via photometry to further…
The formation histories of globular clusters (GCs) are a key diagnostic for understanding their relation to the evolution of the Universe through cosmic time. We use the suite of 25 cosmological zoom-in simulations of present-day Milky…
The formation of globular clusters (GC) with their multiple stellar populations remains a puzzling, unsolved problem in astrophysics. One way to gather critical insight consists in finding sizable numbers of GC progenitors (GCP) while still…
The orbit distribution of young stars in the Galactic disk is highly structured, from well-defined clusters to streams of stars that may be widely dispersed across the sky, but are compact in orbital action-angle space. The age distribution…
The age difference between the two main globular cluster sub-populations in the Virgo giant elliptical galaxy, NGC 4472 (M 49), has been determined using HST WFPC2 images in the F555W and F814W filters. Accurate photometry has been obtained…