Related papers: UV flux variation study in contact binary VW Cephe…

We investigate the spectral properties of the UV ($\lambda\lambda$2650-3050 \AA) and optical ($\lambda\lambda$4000-5500 \AA) Fe II emission features in a sample of 293 type 1 active galactic nuclei (AGNs) from Sloan Digital Sky Survey…

The light variability of hot magnetic chemically peculiar stars is typically caused by the flux redistribution in spots with peculiar abundance. This raises the question why some stars with surface abundance spots show significant…

Young, massive stars dominate the rest-frame ultraviolet spectra of star-forming galaxies. At high redshifts (z>2), these rest-UV features are shifted into the observed-frame optical and a combination of gravitational lensing, deep…

Quasar emission lines are sensitive to both the luminosity and shape of the quasars' high energy continuum - primarily in the soft X-ray and the (obscured) extreme ultraviolet. We initiate the first large-scale, multi-line investigation of…

We present HST/STIS (1160--1700A) echelle spectra of the cataclysmic variable (CV) star, QU Car, observed in time-tag mode at three epochs. In catalogues this binary is classified as a nova-like variable. We find evidence of a high-state…

We studied the spectra of six $z \sim 2.2$ quasars obtained with the X-shooter spectrograph at the Very Large Telescope. The redshift of these sources and X-shooter's spectral coverage allow us to cover the rest spectral range $\sim1200 -…

Featureless optical and ultraviolet (UV) spectra are a puzzling signature to emerge from recent observations of luminous fast blue optical transients (LFBOTs) and some tidal disruption events (TDEs). We describe the landscape of source and…

We present the results of an intensive ground-based spectrophotometric monitoring campaign of the Seyfert galaxy NGC~4151 for a period of over two months, with a typical temporal resolution of one day. Light curves for four optical…

A strong outburst in the X-ray continuum and a change of its Seyfert spectral type was detected in HE 1136-2304 in 2014. The spectral type changed from nearly Seyfert 2 type (1.95) to Seyfert 1.5 type in comparison to previous observations…

Although the star itself is not He enriched, the periodicity and the variability in the UV wind lines of the pulsating B1 IV star beta Cep are similar to what is observed in magnetic He-peculiar B stars, suggesting that beta Cep is…

The star BW Vul excites an extremely strong radial pulsation that grows in its envelope and is responsible for visible shock features in the continuum flux and spectral line profiles emerging in the atmosphere At two phases separated by 0.8…

This project is a massive near-infrared (NIR) search for variable stars in highly reddened and obscured open cluster (OC) fields projected on regions of the Galactic bulge and disk. The search is performed using photometric NIR data in the…

We investigated the effect on the U, B, V magnitudes of the removal of the emission lines from the spectra of some symbiotic stars and novae during their nebular phases. We approached this problem by a precise reconstruction of the…

The so-called ultraviolet (UV) upturn of elliptical galaxies is a phenomenon characterised by the up-rise of their fluxes in bluer wavelengths, typically in the 1,200-2,500A range. This work aims at estimating the rate of occurrence of the…

We characterize ${\sim} 71,200$ W UMa type (EW) contact binaries, including ${\sim} 12,600$ new discoveries, using ASAS-SN $V$-band all-sky light curves along with archival data from Gaia, 2MASS, AllWISE, LAMOST, GALAH, RAVE, and APOGEE.…

We report the discovery of rapid variations of a high-velocity CIV broad absorption line trough in the quasar SDSS J141007.74+541203.3. This object was intensively observed in 2014 as a part of the Sloan Digital Sky Survey Reverberation…

We have used the Far Ultraviolet Spectroscopic Explorer (FUSE) to conduct a snap-shot survey of O VI variability in the winds of 66 OB-type stars in the Galaxy and the Magellanic Clouds. These time series consist of two or three…

We investigate the long-term optical-infrared variability of SV Cep, and explain it in the context of an existing UX Ori (UXOR) model. A 25-month monitoring programme was completed with the Infrared Space Observatory in the 3.3-100 um…

We examine whether the spectral energy distribution of UV continuum emission of active galactic nuclei changes during flux variation. We used multi-epoch photometric data of QSOs in the Stripe 82 observed by the SDSS Legacy Survey and…

We present the results of an intensive ultraviolet monitoring campaign on the Seyfert 1 galaxy NGC 4151, as part of an effort to study its short time-scale variability over a broad range in wavelength. The nucleus of NGC 4151 was observed…