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AG Draconis is a strongly interacting binary system which manifests characteristic symbiotic activity of alternating quiescent and active stages. The latter ones consist of the series of individual outbursts repeating at about a one-year…
The symbiotic binary AG Dra regularly undergoes quiescent and active stages which consist of several outbursts repeating with about 360d interval. The recent outburst activity of AG Dra started by the minor outburst in the late spring of…
AG Draconis is a bright symbiotic binary consisting of a white dwarf and a pulsating cool giant. Moreover, it is the most intense X-ray source among symbiotic stars, and one of the best representatives of the super-soft X-ray objects. The…
Variations of the emission lines in the spectrum of the yellow symbiotic star AG Dra have been studied for over 14 years (1997 - 2011), using more than 500 spectra obtained on the 1.5-metre telescope at Tartu Observatory, Estonia. The time…
AG Dra is a well known bright symbiotic binary with a white dwarf and a pulsating red giant. The long-term photometry monitoring and a new behaviour of the system are presented. The detailed period analysis of photometry as well as…
The recent 1994-1995 active phase of AG Draconis has given us for the first time the opportunity to follow the full X-ray behaviour of a symbiotic star during two successive outbursts and to compare with its quiescence X-ray emission. With…
We analyze an optical light curve of the symbiotic system AG Draconis covering the last 120 years of its history. During the first 32 years the system was in a quiescence state. Around the year 1922 the star's quiescence luminosity…
The dwarf nova CG Dra was intensively monitored during 2005 as part of the Variable Star Sections Recurrent Objects Programme and seven outbursts were detected. These observations were combined with others from the BAA and AAVSO databases…
We report extensive photometry of frequently outbursting dwarf nova IX Draconis. During five months of observations the star went into three superoutbursts and seven ordinary outbursts. This allowed us to determine its supercycle and cycle…
EX Draconis (EX Dra) is a long period dwarf nova showing ~2 mag outburst which lasts for ~7 d and recur on a timescale of (20-30) d. Its deep eclipses allows one to trace the changes in surface brightness and radius of its accretion disk…
AM CVn binaries are the most compact of accreting binaries having orbital periods in the range ~5-70 min. They consist of a white dwarf accreting hydrogen deficient material from a degenerate or semi-degenerate star and are predicted to be…
We present the results of an extensive campaign of coordinated X-ray (ROSAT) and UV (IUE) observations of the symbiotic star AG Dra during a long period of quiescence (1990-1993) followed by two optical outbursts in 1994 and 1995. The hot…
During the British Astronomical Association (BAA) 2022 campaign, 27436 photometric observations of the dwarf nova (DN) CG Draconis were made, with 106 eclipses recorded. This work summarizes the new data available and provides updated…
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…
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 report results of an extensive world-wide observing campaign devoted to a very active dwarf nova star - IX Draconis. We investigated photometric behaviour of the system to derive its basic outburst properties and understand peculiarities…
The symbiotic star AG Dra experienced a double-peaked outburst of 0.6 magnitudes in April and May 2016. Photometry and spectroscopy through the outburst showed the B-V colour index varying linearly with the V magnitude and enabled the…
Symbiotic stars are strongly interacting binaries, consisting of a white dwarf and a cool giant, mainly of spectral type M. AG Draconis belongs to a less numerous group of the yellow symbiotic systems, as the cool component in this binary…
The accretion-powered millisecond pulsar IGR J00291+5934 underwent two ~10 d long outbursts during 2008, separated by 30 d in quiescence. Such a short quiescent period between outbursts has never been seen before from a neutron star X-ray…
A WZ Sge-type dwarf nova, EG Cancri, exhibited six consecutive mini-outbursts with a mean interval of about seven days after the end of the main outburst in 1996/1997. Most unusual was that the star abruptly entered into a deep faint…