We are carrying out a project for studying all the Second Byurakan Survey (SBS) interacting systems of galaxies at z 0.1. The objectives of this project are: (1) to link the histories of the star formation and nuclear activity in these systems with the morphologic type of the interacting galaxies; (2) to settle upper limits to the age of the

Results concerning the dependence of photometric and radial velocity amplitudes on metallicity are presented based on about 200 Galactic classical Cepheids pulsating in the fundamental mode. The Galactic distribution of the [Fe/H] value of Cepheids is also studied. We show that the photometric amplitude ratio AI/AV is independent of metallicity

The Be X-ray binary EXO 2030+375was in an extended low-luminosity state during most of 2016. We observed this state with NuSTARand Swift, supported by INTEGRALobservations and optical spectroscopy with the Nordic Optical Telescope (NOT). We present a comprehensive spectral and timing analysis of these data here to study the accretion geometry and

We present asymptotic giant branch (AGB) models of solar metallicity, to allow the interpretation of observations of Galactic AGB stars, whose distances should be soon available after the first release of the Gaia catalogue. We find an abrupt change in the AGB physical and chemical properties, occurring at the threshold mass to ignite hot bottom

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We present near infrared (J, H and Ks) observations of a 5'× 10' sample field in the Serpens Star Formation region obtained with SOFI at the NTT. These observations are sensitive enough to detect a 20 MJup brown dwarf through an extinction of AV˜ 16 and are used to build an infrared census of this field in the cluster. From photometry and mass