Related papers: Nuclear burning rates and population II stellar mo…
Type-I X-ray bursts can be used to determine properties of accreting neutron stars via comparisons between model calculations and astronomical observations, exploiting the sensitivity of models to astrophysical conditions. However, the…
We present new evolutionary stellar models suitable for old Population I clusters, discussing both the consequences of the most recent improvements in the input physics and the effect of element diffusion within the stellar structures.…
Nuclear rings are excellent laboratories for probing diverse phenomena such as the formation and evolution of young massive star clusters (YMCs), nuclear starbursts, as well as the secular evolution and dynamics of their host galaxies. We…
The 16O(p,gamma)17F reaction rate is revisited with special emphasis on the stellar temperature range of T=60-100 MK important for hot bottom burning in asymptotic giant branch (AGB) stars. We evaluate existing cross section data that were…
We use N-body integration to follow the evolution of clusters of 200 binary systems with different initial half mass radii $R_{0.5}$. We also simulate single-star clusters. All clusters evolve according to the same $n(t)$ curve, where…
Nuclear reactions govern major aspects of the chemical evolution od galaxies and stars. Analytic study of the reaction rates and reaction probability integrals is attempted here. Exact expressions for the reaction rates and reaction…
We derive constraints on the time-averaged event rate of neutron star-black hole (NS-BH) mergers by using estimates of the population-integrated production of heavy rapid neutron-capture (r-process) elements with nuclear mass numbers A >…
We use Cycle 21 Hubble Space Telescope (HST) observations and HST archival ACS Treasury observations of 30 Galactic Globular Clusters to characterize two distinct stellar populations. A sophisticated Bayesian technique is employed to…
Ages have been derived for 55 globular clusters (GCs) from overlays of isochrones onto the turnoff photometry, assuming distances based on fits of zero-age horizontal branch (ZAHB) models to the lower bound of the observed distributions of…
We investigate the quantitative constraint on the triple-alpha reaction rate based on stellar evolution theory, motivated by the recent significant revision of the rate proposed by nuclear physics calculations. Targeted stellar models were…
Globular clusters are dense aggregates of stars that evolve in relative isolation. For the better part of $40$ years these clusters have been known to possess unique chemical signatures called abundance anomalies. Recent observations have…
We investigate the suggestion that there are stellar populations in some globular clusters with enhanced helium (Y from 0.28 to 0.40) compared to the primordial value. We assume that a previous generation of massive Asymptotic Giant Branch…
We present the result of a survey of Monte Carlo simulations of globular clusters hosting two generations of stars including a large (f_b=50%) fraction of primordial binaries in both populations. The dynamical evolution of the two stellar…
Nuclear reactions govern major aspects of the chemical evolution of galaxies and stars. Analytic study of the reaction rates and reaction probability integrals is attempted here. Exact expressions for the reaction rates and reaction…
We estimate the empirical R parameter in 26 Galactic Globular Clusters covering a wide metallicity range, imaged by WFPC2 on board the HST. The improved spatial resolution permits a large fraction of the evolved stars to be measured and…
X-ray bursts are thermonuclear flashes on the surface of accreting neutron stars and reliable burst models are needed to interpret observations in terms of properties of the neutron star and the binary system. We investigate the dependence…
We investigate the structural properties of nuclear star clusters in late-type spiral galaxies. More specifically, we fit analytical models to HST images of 39 nuclear clusters in order to determine their effective radii after correction…
Nuclear reaction rates determine the abundances of isotopes in stellar burning processes. A multitude of reactions determine the reaction flow pattern which is described in terms of reaction network simulations. The reaction rates are…
Most Globular Clusters (GC) show chemical inhomogeneities in the composition of their stars, apparently due to a second stellar generation (SG) in which the forming gas is enriched by hot-CNO cycled material processed in stars belonging to…
Explosive nuclear burning in astrophysical environments produces unstable nuclei which again can be targets for subsequent reactions. In addition, it involves a large number of stable nuclides which are not fully explored by experiments,…