Related papers: Multimodal Horizontal Branches: Empirical Evidence…
Surface temperature distribution of horizontal-branch (HB) stars is very sensitive to age in old stellar systems, which makes it an attractive age indicator. In this paper, we present the recent revision of our model calculations for the HB…
Recent observations and theories suggest that extreme horizontal branch (EHB) stars and their progeny should be the cause of the UV excess seen in the spectra of many elliptical galaxies. Since the Galactic Bulge is the closest…
Increasing samples of pulsating variable stars populating the classical instability strip from the horizontal branch to a few magnitudes brighter are being found in several Local Group galaxies, irrespective of the galaxy morphological…
Context. Abundance anomalies have been observed in field sdB stars and in nearly all Horizontal Branch (HB) stars of globular clusters with Teff > 11 000K whatever be the cluster metallicity. Aims. The aim is to determine the abundance…
Recent observations and models for horizontal branch stars are briefly described and compared to models for AmFm stars. The limitations of those models are emphasized by a comparison to observations and models for HgMn stars.
The Horizontal Branch (HB) morphology in the color -- magnitude diagram of the Galactic globular clusters depends on many factors, and it is now firmly established that the so-called Second Parameter is not just the cluster age as claimed…
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…
Field Horizontal branch (HB) stars can be used as tracers for the study of early stages of the evolution of our galaxy. Since the age of individual HB stars is not known a priori, we have studied the kinematics of a sample of field HB stars…
Theory and observations indicate that the distribution of stars along the horizontal branch of Galactic globular clusters mainly depends on the metal content. However, the existence of globular clusters with similar metal content and…
We study the distribution of exoplanets around main sequence (MS) stars and apply our results to the binary model for the formation of extreme horizontal branch (EHB; sdO; sdB; hot subdwarfs) stars. By Binary model we refer both to stellar…
An increasing number of photometric observations of multiple stellar populations in Galactic globular clusters is seriously challenging the paradigm of GCs hosting single, simple stellar populations. These multiple populations manifest…
To address the puzzling photometric properties of horizontal branch stars in Galactic GCs, several different groups have undertaken detailed spectroscopic analyses of individual blue HB stars. Hotter BHB stars show strong metal enhancement…
Recent pieces of evidence have revealed that most, and possibly all, globular star clusters are composed of groups of stars that formed in multiple episodes with different chemical compositions. In this sense, it has also been argued that…
Horizontal Branch stars belong to an advanced stage in the evolution of the oldest stellar galactic population, occurring either as field halo stars or grouped in globular clusters. The discovery of multiple populations in these clusters,…
Horizontal branch (HB) stars play a particularly important role in the "age debate," since they are at the very center of the long-standing "second parameter" problem. In this review, I discuss some recent progress in our understanding of…
The connection between mass loss on the red giant branch (RGB) and horizontal branch (HB) morphology in globular clusters (GCs) has long been acknowledged but the mechanisms governing mass loss remains poorly understood from a theoretical…
This series of papers comprises a systematic exploration of the hypothesis that the far ultraviolet radiation from star clusters and elliptical galaxies originates from extremely hot horizontal-branch (HB) stars and their post-HB progeny.…
Blue horizontal-branch (BHB) stars are evolved low-mass objects that have completed their core hydrogen burning main-sequence (MS) stage and have lost significant mass during the red giant phase culminating in the helium flash. We determine…
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…
The horizontal branch (HB) morphology of globular clusters (GCs) is mainly described by metallicity. The fact that some clusters with almost the same metallicity exhibit different HB demonstrates that other parameters are at work. We…