Variable behavior on all time scales seems to be ubiquitous phenomenon in almost all classes of active galactic nuclei. This work deals with two topics. One being detection of microvariability (intra-night variability) in the sources which are obscured and were believed to be non variable - type 2 quasars. The detection of a variable behavior in

We present the discovery of the hot subdwarf B star (sdB) binary PTF1 J082340.04+081936.5. The system has an orbital period of {P}{orb} = 87.49668(1) minutes (0.060761584(10) days), making it the second-most compact sdB binary known. The light curve shows ellipsoidal variations. Under the assumption that the sdB primary is synchronized with the

We use single-epoch spectroscopy of three gravitationally lensed quasars, HE 0435-1223, WFI 2033-4723, and HE 2149-2745, to study their inner structure (broad-line region [BLR] and continuum source). We detect microlensing-induced magnification in the wings of the broad emission lines of two of the systems (HE 0435-1223 and WFI 2033-4723). In the

The characterization of the Galactic foregrounds has been shown to be the main obstacle in thechallenging quest to detect primordial B-modes in the polarized microwave sky. We make use of the Planck-HFI 2015 data release at high frequencies to place new constraints on the properties of the polarized thermal dust emission at high Galactic latitudes

Local extremely metal-poor galaxies (XMPs) are of particular astrophysical interest since they allow us to look into physical processes characteristic of the early universe, from the assembly of galaxy disks to the formation of stars in conditions of low metallicity. Given the luminosity–metallicity relationship, all galaxies fainter than M r ≃ ‑13

Aims: We aim to develop an efficient method to search for late-type subdwarfs (metal-depleted dwarfs with spectral types ≥M5) to improve the current statistics. Our objectives are to improve our knowledge of metal-poor low-mass dwarfs, bridge the gap between the late-M and L types, determine their surface density, and understand the impact of