Related papers: On constructing horizontal branch models
I review aspects of the evolution of horizontal branch (HB) stars. I start by discussing current topics in the study of HB stellar evolution, including a brief review of the main determinants of the structure of low-mass core helium burning…
We describe the GALFORM semi-analytic model for calculating the formation and evolution of galaxies in hierarchical models. It improves upon, and extends, the Cole et al 1994 model. The model employs a new Monte-Carlo algorithm to follow…
Advances in extragalactic astronomy have prompted the development of increasingly realistic models which aim to describe the formation and evolution of galaxies. We review the philosophy behind one such technique, called semi-analytic…
Semi-analytic models are best suited to compare galaxy formation and evolution theories with observations. These models rely heavily on halo merger trees, and their realistic features (i.e., no drastic changes on halo mass or jumps on…
We present here results of stellar evolution calculations that include the latest advances in radiative opacities and neutrino cooling, and discuss on the basis of these models how the internal stellar structure responds to mass-loss from…
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…
We present a grid of evolutionary calculations for metal-poor low-mass stars for a variety of initial helium and metal abundances. The intention is mainly to provide a database for deriving directly stellar ages of halo and globular cluster…
Masking the horizontal branch and giant stars allows unambiguous measurements of mean age and metallicity in simple old stellar populations from metal and hydrogen line strengths. Billion year resolution is possible in the luminous halos of…
We develop a simple, fast and predictive model of the hierarchical formation of galaxies which is in quantitative agreement with observations. Comparing simulations with observations we place constraints on the density of the universe and…
A major source of uncertainty in the age determination of old ($\sim10$ Gyr) integrated stellar populations is the presence of hot horizontal branch (HB) stars. Here, we describe a simple approach to tackle this problem, and show the…
Stellar models provide a vital basis for many aspects of astronomy and astrophysics. Recent advances in observational astronomy -- through asteroseismology, precision photometry, high-resolution spectroscopy, and large-scale surveys -- are…
Diffusion of elements in the atmosphere and envelope of a star can drastically alter its surface composition, leading to extreme chemical peculiarities. We consider the case of hot subdwarfs, where surface helium abundances range from…
We present analytic formulae that approximate the evolution of stars for a wide range of mass and metallicity. Stellar luminosity, radius and core mass are given as a function of age, M and Z, for all phases from the zero-age main-sequence…
We investigate the ability of the Croton et al. (2006) semi-analytic model to reproduce the evolution of observed galaxies across the final 7 billion years of cosmic history. Using Monte-Carlo Markov Chain techniques we explore the…
Globular clusters offer ideal laboratories to test the predictions of stellar evolution. When doing so with spectroscopic analyses during the 1990s, however, the parameters we derived for hot horizontal branch stars deviated systematically…
In recent years, simple models of galaxy formation have been shown to provide reasonably good matches to available data on high-redshift luminosity functions. However, these prescriptions are primarily phenomenological, with only crude…
Theoretical integrated broad-band colors ranging from far-UV to near-IR have been computed for old stellar systems from our evolutionary population synthesis code. These models take into account, for the first time, the detailed systematic…
A generalization of the multiphase chemical evolution model applied to a wide set of theoretical galaxies is shown. This set of models has been computed by using the so-called Universal Rotation Curve from Persic, Salucci & Steel to…
Any realistic theory of galaxy formation must be set in the context of a model for the formation of structure in the universe. We describe a powerful approach -- semi-analytic modelling -- that combines a set of simple rules describing the…
In this paper, we study how to construct f(R) gravity models. Cosmological observations and local gravity tests imply that a viable f(R) model should be very close to the LCDM model. We create procedures to construct viable LCDM-like f(R)…