Related papers: Outburst activity of symbiotic system AGDra
A number of asymptotic giant branch (AGB) stars are known to exhibit UV excess and/or X-ray emission. These have been considered signposts of a hot white dwarf (WD) companion in a symbiotic system (SySt), but AGB stars are so bright that…
We present new observations of the central binary inside the Red Rectangle nebula. The detection of zinc in the optical spectrum confirms that the peculiar photospheric abundances are due to accretion of circumstellar gas. Grey brightness…
We present highlights and an overview of 20 FUSE and HST/STIS observations of the bright symbiotic binary EG And. The main motivation behind this work is to obtain spatially-resolved information on an evolved giant star in order to…
New observations of GD 99 are analysed. The unusual pulsation behaviour, showing both long and short periods, has been confirmed. All the available periods show a grouping of short and long period modes with roughly regular spacing. If we…
We report on our survey for rapid (time scale of minutes) photometric variability in symbiotic binaries. These binaries are becoming an increasingly important place to study accretion onto white dwarfs since they are candidate Type Ia…
We present an analysis of optical and near infrared spectra of the symbiotic system AE Ara, composed of an M5.5 III giant similar to the Galactic Bulge M giants and a hot luminous companion. In particular, we have determined for the first…
We propose a compact binary model with an eccentric orbit to explain periodically active fast radio burst (FRB) sources, where the system consists of a neutron star (NS) with strong dipolar magnetic fields and a magnetic white dwarf (WD).…
The variable star AR Sco was recently discovered to pulse in brightness every 1.97 min from ultraviolet wavelengths into the radio regime. The system is composed of a cool, low-mass star in a tight, 3.55 hr orbit with a more massive white…
We model the evolution of 21 Gaia neutron star (NS)-main-sequence binaries (orbital period $P_{\mathrm{orb}}\sim200$--$1000$ days, eccentricity $e\gtrsim0.2$) using binary evolution with \texttt{MESA}. We examine eccentric mass transfer and…
We have used long-term AAVSO visual observations and Fourier and wavelet analysis to identify periods and study long-term amplitude variations in 44 red supergiants. Of these, 12 stars had data which were too sparse and/or had low amplitude…
Following the GRB 170817A prompt emission lasting a fraction of a second, $10^8$ s of data in the X-rays, optical, and radio wavelengths have been acquired. We here present a model that fits the spectra, flux, and time variability of all…
In this papper we present the analyses of the six (1998, 1997, 2001, 2002, 2003 and 2005) last outbursts of AG Draconis on the basis of low resolution visual spectroscopy. A new method to determine the Zanstra's temperature of the hot…
We present spectroscopic and imaging observations of the active T dwarf 2MASS 1237+6526, intended to investigate the emission mechanism of this cool brown dwarf. The H$\alpha$ emission line first detected in 1999 July appears to be…
Two-dimensional gas-dynamical modeling of the mass-flow structure is used to study the outburst development in the classical symbiotic star Z And. The stage-by-stage rise of the light during the outburst can be explained in the framework of…
The red giant ${\delta}$ Muscae is known since 1919 to be a spectroscopic binary, and the first and only orbit was determined in 1936, claiming the period to be 847 days. This was discrepant with the Hipparcos determined astrometric orbit.…
Line profiles containing indication of bipolar collimated outflow along with P Cyg absorption during phase of activity of several symbiotic systems are considered. The Hgamma profile of Z And during its 2006 outburst consisted of four…
We present new optical spectroscopy and photometry, 2MASS infrared observations and 24 years of combined AAVSO and AFOEV photometry of the symbiotic star candidate \ae. The long-term light curve is characterized by outbursts lasting several…
We report simultaneous photometric and echelle-spectroscopic observations of the dwarf nova BZ UMa during which we were lucky to catch the system at the onset of an outburst, the development of which we traced in detail from quiescence to…
(Summary of paper) High resolution optical spectroscopy of the white dwarf WD0137-349 reveals a weak Halpha line in emission, due to a low mass companion in a close orbit. Using this emission feature, and the narrow NLTE core of the white…
Using the disc instability model and a simple but physically reasonable model for the X-ray, extreme UV, UV and optical emission of dwarf novae we investigate the time lags observed between the rise to outburst at different wavelengths. We…