Related papers: Multiwavelength observations of KS 1947+300
The Be X-ray Binary 4U 0115+63 was observed by Large Area X-ray Proportional Counter (LAXPC) instrument on AstroSat on 2015 October 24 during the peak of a giant Type II outburst. Prominent intensity oscillations at ~ 1 and ~ 2 mHz…
The optical behaviour of the Be star in the high-mass X-ray transient A0535+26/HDE245770 shows that at periastron the luminosity is typically enhanced by 0.02 to a few tenths magnitude, and the X-ray outburst occurs eight days after the…
The Be/X-ray binary 1A 0535+262 underwent a giant X-ray outburst in November 2020, peaking at $\sim1\times 10^{38}$ erg s$^{-1}$ (1--100 keV, 1.8 kpc), the brightest outburst recorded for this source so far. Our goal is to search for…
We have used INTEGRAL & RXTE data to investigate the timing properties of the source in correlation with its spectral states as defined by different positions in the colour-colour diagram. The source shows two distinct branches in the…
Classical Be stars are hot non-supergiant stars surrounded by a gaseous circumstellar disk that is responsible for the observed infrared (IR) excess and emission lines. The influence of binarity on these phenomena remains controversial. We…
Multiwavelength observations are reported here of the Be/X-ray binary pulsar system GRO J1008-57. Over ten years worth of data are gathered together to show that the periodic X-ray outbursts are dependant on both the binary motion and the…
Short-period high-amplitude pulsating stars of Population I ($\delta$ Sct stars) and II (SX Phe variables) exist in the lower part of the classical (Cepheid) instability strip. Most of them have very simple pulsational behaviours, only one…
Using simultaneous observations in X-rays and optical, we have performed a homogeneous analysis of the cross-correlation behaviours of four X-ray binaries: SWIFT J1753.5-0127, GX 339-4, Sco X-1, and Cyg X-2. With high time-resolution…
X-rays trace accretion onto compact objects in binaries with low mass companions at rates ranging up to near Eddington. Accretion at high rates onto neutron stars goes through cycles with time-scales of days to months. At lower average…
The Be/X-ray binary A0535+26 showed a giant outburst in December 2009 that reached ~5.14 Crab in the 15-50 keV range. Unfortunately, due to Sun constraints it could not be observed by most X-ray satellites. The outburst was preceded by four…
The Be/X-ray transient GRO J1750-27 exhibited a type-II (giant) outburst in 2015. After the source transited to quiescence, we triggered our multi-year Chandra monitoring programme to study its quiescent behaviour. The programme was…
We have been monitoring the binary system V0332+53 (optical counterpart is BQ Cam) since 2004 using 45 cm ROTSEIIId telescope and RTT150 (Russian-Turkish 1.5 m Telescope) located at Bakirlitepe, Antalya, Turkey. We report on the long-term…
We study X-ray and UV emission from the narrow-line Seyfert 1 galaxy II~Zw~177 using a $137\ks$ long and another $13\ks$ short \xmm{} observation performed in 2012 and 2001, respectively. Both observations show soft X-ray excess emission…
The gamma-ray binary LS I +61 303 is composed of a Be star and a compact companion orbiting in an eccentric orbit. Variable flux modulated with the orbital period of ~26.5 d has been detected from radio to very high-energy gamma rays. In…
LSI +61 303 is an exotic binary system consisting of a ~10 Msun B star and a compact object which is probably a neutron star. The system is associated with the interesting radio source GT0236+610 that exhibits bright radio outbursts with a…
In this paper we study the timing and spectral properties of Be/X-ray binary pulsar EXO 2030+375 using a $Suzaku$ observation on 2012 May 23, during a less intense Type I outburst. Pulsations were clearly detected in the X-ray light curves…
We study the variability of the cataclysmic variable DO Dra, on time-scales of between minutes and decades. The characteristic decay time dt/dm=0.902(3) days/mag was estimated from our 3 nights of CCD R observations. The quiescent data show…
We report on the full analysis of a Rossi X-ray Timing Explorer (RXTE) Proportional Counter Array (PCA) monitoring of the {\gamma}-ray binary system LS I +61 303. The data set covers 42 contiguous cycles of the system orbital motion.…
We present a comprehensive analysis of the optical and infrared (IR) properties of high-mass X-ray binary (HMXB) IC 10 X-2, classified as a super-giant HMXB and super-fast X-ray transient (SFXT) by previous work. Our analysis of regular…
X-ray binaries exhibit complex variability patterns studied in the power-spectrum. These include the broad-band noise (BBN) components and various types of narrow components called quasi-periodic oscillations (QPOs). There is currently no…