Related papers: Calcium Emission in Interacting Binary Be Stars

We report the discovery of very-high-energy (VHE) gamma-ray emission of the binary system PSR B1259-63/SS 2883 of a radio pulsar orbiting a massive, luminous Be star in a highly eccentric orbit. The observations around the 2004 periastron…

For a fraction of single white dwarfs with debris disks, an additional gaseous disk was discovered. Both dust and gas are thought to be created by the disruption of planetary bodies. The composition of the extrasolar planetary material can…

Pulsating stars in eclipsing binary systems play an important role in asteroseismology. The combination of their spectroscopic and photometric orbital solutions can be used to determine, or at least to constrain, the masses and radii of…

The origin of nebular HeII emission, which is frequently observed in low-metallicity (O/H) star-forming galaxies, remains largely an unsolved question. Using the observed anticorrelation of the integrated X-ray luminosity per unit of star…

We present the enigmatic galactic unclassified B[e] star Hen 2-90. Its optical spectrum is discussed and analysed in terms of the forbidden emission lines coming from a non-spherical wind. The evolutionary phase of Hen 2-90 is discussed. We…

We focus on two Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) spectra of the Weigelt Blobs B&D, extending from 1640 to 10400A; one recorded during the 1998 minimum (March 1998) and the other recorded in February…

A reliable determination of the basic physical properties and variability patterns of hot emission-line stars is important for understanding the Be phenomenon and ultimately, the evolutionary stage of Be stars. This study is devoted to one…

For the first time, we have identified photospheric emission lines in the far-UV spectrum of a white dwarf. They were discovered in the Far Ultraviolet Spectroscopic Explorer spectrum of the hot (Teff~200,000 K) DO white dwarf KPD0005+5106…

Classical Be (CBe) stars are rapidly rotating B-type stars with Balmer emission lines that originated from the decretion disks surrounding them in their spectra. Accounting for $\sim$20% of all B-type stars, most CBe stars are thought to…

Chromospherically Active Binaries (CAB) catalogue have been revised and updated. With 203 new identifications, the number of CAB stars is increased to 409. Catalogue is available in electronic format where each system has various number of…

Current ongoing stellar spectroscopic surveys (RAVE, GALAH, Gaia-ESO, LAMOST, APOGEE, Gaia) are mostly devoted to studying Galactic archaeology and structure of the Galaxy. But they allow for important auxiliary science: (i) Galactic…

We propose a model to account for the bolometric light curve, quasi-continuum and the Ca II emission features of the peculiar type Ia supernova (SN) 2002ic, which exploded in a dense circumstellar envelope. The model suggests that the SN Ia…

We verify the nature of emission-line stars in the field of the open cluster NGC 6910. % Spectroscopy in the H-alpha region was obtained. Raw CCD frames of spectra of all stars fainter than V = 9 mag observed by us are significantly…

The atlas of the spectrum of the B[e] star CI Cam obtained with the 6-meter BTA telescope in combination with the NES spectrograph in the wavelength interval of 395$\div$780 nm with a resolution of $\lambda/\Delta\lambda\ge60\,000$ is…

Ultra-hot Jupiters are highly irradiated gas giants with equilibrium temperatures typically higher than 2000K. Atmospheric studies of these planets have shown that their transmission spectra are rich in metal lines, with some of these…

Distant luminous Lyman-alpha emitters (LAEs) are excellent targets for spectroscopic observations of galaxies in the epoch of reionisation (EoR). We present deep high-resolution (R=5000) VLT/X-SHOOTER observations, along with an extensive…

Classical Cepheids (CCs) and RR Lyrae stars (RRLs) are important classes of variable stars used as standard candles to estimate galactic and extragalactic distances. Their multiplicity is imperfectly known, particularly for RRLs.…

Previous studies on the rotation of Sun-like stars revealed that the rotational rates of young stars converge towards a well-defined evolution that follows a power-law decay. It seems, however, that some binary stars do not obey this…

The nature of non-variable high-excitation emission lines detected in the optical spectra of normal late-B type and chemically peculiar HgMn and PGa stars is still poorly understood. To better understand the origin of the weak emission…

We present spectra of a sample of Herbig Ae and Be (HAeBe) stars obtained with the Infrared Spectrograph on the Spitzer Space Telescope. All but one of the Herbig stars show emission from polycyclic aromatic hydrocarbons (PAHs) and seven of…