Eighteen RR Lyrae variables (RRLs) that lie in the ``12.4h clump'' identified by the Quasar Equatorial Survey Team (QUEST) have been observed spectroscopically to measure their radial velocities and metal abundances. Ten blue horizontal branch (BHB) stars identified by the Sloan Digital Sky Survey (SDSS) were added to this sample. Six of the nine

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In this paper, we present a study of the general physical and chemical properties and radial velocity monitoring of young active stars. We derive temperatures, logg, [Fe/H], v sini and Rspec values for eight stars. The detailed analysis reveals that the stars are not homogeneous in their principal physical parameters or in the age distribution. In

Since 1995, more than 140 planets around solar-type stars have been discovered. The great success of the first decade of observational research in exoplanets, where both the number of planets detected and the number of research groups in the field have grown in parallel, will be followed by a golden age in exoplanet discovery. In the next 15 years

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We present a spectrophotometric analysis of S Ori J053825.4-024241, a candidate member close to the substellar boundary of the young (1-8 Myr), nearby (~360 pc) σ Orionis star cluster. Our optical and near-infrared photometry and low-resolution spectroscopy indicate that S Ori J053825.4-024241 is a likely cluster member with a mass estimated from