An abundance analysis is presented of 60 metal-poor stars drawn from catalogues of nearby stars provided by Ariyanto et al. (2005) and Schuster et al. (2006). In an attempt to isolate a sample of metal-weak thick disc stars, we applied the kinematic criteria Vrot ≥ 100 km s , |ULSR| ≤ 140 km s , and |WLSR| ≤ 100 km s . Fourteen stars satisfying these criteria and having [Fe/H] ≤ −1.0 are includ...

To properly understand the physics of Ap and Bp stars it is particularly important to identify the origin of their magnetic fields. For that, an accurate knowledge of the evolutionary state of stars that have a measured magnetic field is an important diagnostic. Previous results based on a small and possibly biased sample suggest that the distribution of magnetic stars with mass below 3M⊙ in th...

The rotation periods of the host stars of extrasolar planets have been assessed against those of the Mt. Wilson stars, open cluster stars, and evolutionary stellar models that include rotation. They appear to be normal, modulo certain inconsistencies in various necessary inputs. Selection of candidate planet hosts for radial velocity surveys by low rotation or activity has resulted in a planet ...

Theoretical models of very metal-poor intermediate-mass Asymptotic Giant Branch (AGB) stars predict a large overabundance of primary nitrogen. The very metal-poor, carbon-enhanced, s-process-rich stars, which are thought to be the polluted companions of now-extinct AGB stars, provide direct tests of the predictions of these models. Recent studies of the carbon and nitrogen abundances in metal-p...

Horizontal branch (HB) stars in the field of the Milky Way 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 measured with Hipparcos to look for signs of age and population nature. Our sample comprises 14 HBA, 2 HBB and 5 sdB/O stars. We fou...

We carried out a search for M–type Vega–like stars by correlating the IRAS Faint Source Catalog with Hipparcos selected M–type stars. Three stars with apparent IRAS 25 μm excess emission are shown instead to be non–IR–excess stars from ground–based 11.7 and 17.9 μm photometry. Two stars previously suggested to have Vega–like mid–IR excess are also shown to be non–excess stars. These results imp...

Binary stars are important for a full understanding of stellar evolution. We present a summary of how predictions of the relative supernova rates varies between single and binary stars. We also show how the parameter space of different supernova types differs between single and binary stars. We then consider an important question of how to infer a supernova progenitor’s properties from pre-expl...

It is known that most visible stars are binary: they have a nearby companion star, and these two stars orbit around each other. Based on this fact, until recently, astronomers believed that, in general, most stars are binary. A few years ago, a surprising paper showed that while most bright stars are indeed binary, most dim stars are single. In this paper, we provide a simple qualitative explan...

We report the discovery of 5 massive Wolf-Rayet (WR) stars resulting from a programme of follow-up spectroscopy of candidate emission line stars in the AAO/UKST Southern Galactic Plane Hα survey. The 6195-6775 Å spectra of the stars are presented and discussed. A WC9 class is assigned to all 5 stars through comparison of their spectra with those of known latetype WC stars, bringing the known to...