We present new high-resolution near-IR spectroscopy and OH maser observations to investigate the population of cool luminous stars of the young massive Galactic cluster RSGC1. Using the 2.293 μm CO band-head feature, we make high-precision radial velocity measurements of 16 of the 17 candidate red supergiants (RSGs) identified by Figer et al. We

We present a new method to derive the age of young (

A series of recent studies has placed the best estimates of the photospheric abundances of carbon and oxygen at log ɛ =8.39 and 8.66, respectively. These values are ˜ 40 % lower than earlier estimates. A coalition of corrections due to the adoption of an improved model atmosphere, updated atomic data and non-LTE corrections, and a reevaluation of

Using the high-resolution cosmological N-body simulation MareNostrum universe we study the orientation of shape and angular momentum of galaxy-size dark matter haloes around large voids. We find that haloes located on the shells of the largest cosmic voids have angular momenta that tend to be preferentially perpendicular to the direction that joins

We conducted spectroscopic studies of both components of the visual binary HR 1847 to determine its basic physical and orbital parameters. New observations of this system were obtained using the Ondřejov and Rozhen 2-m telescopes. Radial velocities were measured using the individual spectra and then analysed using the FOTEL code to determine

Aims: We present optical photometry and spectroscopy of the afterglow and host galaxy of gamma-ray burst GRB 040924. This GRB had a rather short duration of T90 ~2.4 s, and a well sampled optical afterglow light curve. We aim to use this dataset to find further evidence that this burst is consistent with a massive star core-collapse progenitor