Related papers: Multimodal Horizontal Branches: Empirical Evidence…
Star-to-star variations in abundances of the light elements carbon, nitrogen, oxygen, and sodium have been observed in stars of all evolutionary phases in all Galactic globular clusters that have been thoroughly studied. The data available…
The discovery of multiple stellar populations in globular clusters has implications for all the aspects of the study of these stellar systems. In this paper, by means of N-body simulations, we study the evolution of binary stars in…
Globular clusters are ideal laboratories to study the evolution of low-mass stars. In this work we concentrate on three types of hot stars observed in globular clusters: horizontal branch stars, UV bright stars, and white dwarfs. After…
Black holes (BHs) play a major role in the structural and dynamical evolutions of Globular Clusters (GCs). Several recent works searched for BHs in Galactic GCs using scaling relations derived from numerical simulations. However, the…
The discrepancy between a LONG distance scale derived from Hipparcos based distances to globular clusters via main sequence fitting to local subdwarfs, and a SHORT distance scale derived from the absolute magnitude of field RR Lyraes via…
We investigate the distribution of stars along the Horizontal Branch of the Galactic globular cluster NGC1851, to shed light on the progeny of the two distinct Subgiant Branch populations harbored by this cluster. On the basis of detailed…
Observations of the high energy sky, mainly with the INTEGRAL satellite, have raised new questions about the formation and evolution of High Mass X-ray Binaries (HMXBs). The number of detected HMXBs of different types is now high enough to…
The UV-initiative Hubble Space Telescope Treasury survey of Galactic globular clusters provides a new window into the phenomena that shape the morphological features of the horizontal branch (HB). Using this large and homogeneous catalog of…
Observational advances over the last decade have enabled high-resolution, interferometric studies of forming multiple systems, statistical surveys of multiplicity in star-forming regions, and new insights into disk evolution and planetary…
Globular Clusters (GCs) exhibit star-to-star variations in specific elements (e.g., He, C, N, O, Na, Al) that bare the hallmark of high temperature H burning. These abundance variations can be observed spectroscopically and also…
Globular clusters contain many stars with surface abundance patterns indicating contributions from hydrogen burning products, as seen in the anti-correlated elemental abundances of e.g. sodium and oxygen, and magnesium and aluminium.…
As stars which have planetary systems evolve along the red giant branch and expand, they interact with the close planets. The planets deposit angular momentum and energy into the red giant stars' envelopes, both of which are likely to…
An overview of pulsating variable stars across the observational Hertzprung-Russel (HR) diagram is presented, together with a summary of their global properties. The HR diagram is presented with a third colour-coded dimension, visualizing…
We report the discovery of a peculiar horizontal branch (HB) in NGC 6440 and NGC 6569, two massive and metal-rich Galactic globular clusters (GGCs) located in the Galactic bulge, within 4 kpc from the Galactic Center. In both clusters, two…
The SMC represents an exciting opportunity to observe the direct results of tidal interactions on star birth. One of the best indicators of recent star birth activity is the presence of signicant numbers of High-Mass X-ray Binaries (HMXBs)…
In this review, I will discuss a few problems which point to the need for improved stellar evolution models of halo stars. Current stellar evolution models do not match the observed $^7$Li abundance patterns, suggesting that the input…
We review recent studies on the morphology and distribution with respect to the galactic plane of planetary nebulae (PNs), as well as recent advances in MHD modeling of PNs. We discuss a tentative explanation for the connection between…
The secular evolution process, which slowly transforms the morphology of a galaxy over its lifetime, could naturally account for observed properties of the great majority of physical galaxies if both stellar and gaseous accretion processes…
Subdwarf B (sdB) stars form the blue end of the horizonal branch (EHB). Their peculiar atmospheric abundance patterns are due to diffusion processes. However, diffusion models fail to explain these anomalies quantitatively. Weak mass loss…
Long-duration gamma-ray bursts are the manifestations of massive stellar death. Due to the immense energy release they are detectable from most of the observable universe. In this way they allow us to study the deaths of single (or binary)…