相关论文: Do globular clusters time the Universe?
Globular clusters (GCs) are typically old, with most having formed at z >~ 2. This makes understanding their birth environments difficult, as they are typically too distant to observe with sufficient angular resolution to resolve GC birth…
The present paper presents a tabulation of data on all 600 Galactic open clusters for which it is presently possible to calculate linear diameters. As expected, the youngest `clusters' with ages < 15 Myr, contain a significant (greater than…
Despite the rapid observational progress in the study of young massive star clusters, the formation of globular clusters still remains poorly understood. Yet, it is emerging that globular cluster formation is intimately linked to the…
Globular clusters (GCs) are among the oldest and most luminous stellar systems in the Universe, offering unique insights into galaxy formation and evolution. While the physical processes behind their origin have long remained elusive, major…
We discuss the present state of knowledge and thought concerning the spread in age found among Galactic globular clusters, with some discussion of the implications for what happened during the earliest stages of the formation of the Milky…
A new cosmological model makes the following predictions: (1) The deceleration parameter $q_{0}$ is approximately zero. (2) The mass density parameter $\Omega_{m}$ is less than 1. (3) The universe is spatially closed, but is asymptotically…
We determine ages of 71 old Open Clusters by a two-step method: we use main-squence fitting to 10 selected clusters, in order to obtain their distances, and derive their ages from comparison with our own isochrones used before for Globular…
The large scale structure of the present Universe is determined by the growth of dark matter density fluctuations and by the dynamical action of dark energy and dark matter. While much progress has been made in recent years in constraining…
Despite the tremendous advance of observational cosmology, the value of the Hubble constant ($H_0$) is still controversial (the so called ``Hubble tension'') because of the inconsistency between local/late-time measurements and those…
Numerical simulations of a Milky Way-size galaxy demonstrate that globular clusters with the properties similar to observed can form naturally at z > 3 in the concordance Lambda-CDM cosmology. The clusters in our model form in the strongly…
The formation details of globular clusters (GCs) are still poorly understood due to their old ages and the lack of detailed observations of their formation. A large variety of models for the formation and evolution of GCs have been created…
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…
The discussion of cosmological parameters used to be a source of embarrassment to cosmologists. Today, measurements of the cosmological parameters are leading the way into the era of precision cosmology. The CMB temperature is measured to…
The details of the CMB power spectrum are being revealed through the combined efforts of the world's CMBologists. The current data set constrains several cosmological parameters. A combination with other (non-lensing) constraints yields…
An overview of our current understanding of the formation and evolution of star clusters is given, with main emphasis on high-mass clusters. Clusters form deeply embedded within dense clouds of molecular gas. Left-over gas is cleared within…
The ages of globular clusters in our own Milky Way are known with precision of about \pm 1 Gyr, hence their formation at redshifts z>~3 and their role in hierarchical cosmology and the reionization of the intergalactic medium remain…
We review many of the basic properties of star cluster systems, and focus in particular on how they relate to their host galaxy properties and ambient environment. The cluster mass and luminosity functions are well approximated by…
We investigate the cosmic age problem associated with 9 extremely old globular clusters in M31 galaxy and 1 very old high-$z$ quasar APM 08279 + 5255 at $z=3.91$. These 9 globular clusters have not been used to study the cosmic age problem…
We present a statistical approach for determining the age of Globular Clusters (GCs) that allows estimating the age derived from CMDs more accurately than the conventional methods of the isochrone fitting. We measure how closely a set of…
An impressive amount of different astrophysical data converges towards the picture of a spatially flat universe undergoing a today phase of accelerated expansion. The nature of the dark energy dominating the energy content of the universe…