Related papers: Be/X-ray binaries
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…
Be stars make up almost 20% of the B star population, and are rapidly rotating stars surrounded by a disc; however the origin of this rotation remains unclear. Mass transfer within close binaries provides the leading hypothesis, with…
Circumstellar discs of Be stars are thought to be formed from material ejected from a fast-spinning central star. This material possesses large amounts of angular momentum and settles in a quasi-Keplerian orbit around the star. This simple…
Dynamical interactions that take place between objects in dense stellar systems lead to frequent formation of exotic stellar objects, unusual binaries, and systems of higher multiplicity. They are most important for the formation of…
We present evidence for a simple linear relationship between the orbital period and super-orbital period in ultra-luminous X-ray (ULX) pulsars, akin to what is seen in the population of disc-fed neutron star super-giant X-ray binary and…
We use a smoothed particle hydrodynamics (SPH) code to examine the effects of misaligned binary companions on Be star discs. We systematically vary the degree of misalignment between the disc and the binary orbit, as well as the disc…
This paper summarizes our recent results on tidal interaction in high mass X-ray binaries and symbiotic stars. We demonstrate that the giant in symbiotic stars with orbital periods <1200 d are co-rotating (synchronized). The symbiotics MWC…
Debris disc analysis and modelling provide crucial information about the structure and the processes at play in extrasolar planetary systems. In binary systems, this issue is more complex because the disc should in addition respond to the…
We use a smoothed particle hydrodynamics (SPH) code to examine the effects of a binary companion on a Be star disk for a range of disk viscosities and misalignment angles, i.e. the angle between the orbital plane and the primary's spin…
Motivated by misaligned discs observed in eccentric orbit Be/X-ray binaries, we examine the evolution of a retrograde disc around one component of an eccentric binary with hydrodynamic simulations, $n$-body simulations and linear theory.…
We present the spectroscopic and photometric observations on the Be/X-ray binary RX~J0440.9+4431 from 2001 to 2014. The short-term and long-term variability of the H$\alpha$ line profile indicates that one-armed global oscillations existed…
Circumbinary discs are generally thought to take up angular momentum and energy from the binary orbit over time through gravitational torques mediated by orbital resonances. This process leads to the shrinkage of the binary orbit over time,…
Stellar companions of accreting neutron stars in ultra compact X-ray binaries (UCXBs) are hydrogen-deficient. Their helium or C/O accretion discs are strongly X-ray irradiated. Both the chemical composition and irradiation determine the…
SXP 5.05 is a Be/X-ray binary with a neutron star companion located in the Small Magellanic Cloud. It was first detected in 2013, and later that year, SXP 5.05 underwent a massive optical and X-ray outburst. This outburst dwarfs any other…
With hydrodynamic simulations we show that a coplanar disc around one component of a binary can be unstable to global tilting when the disc orbits in a retrograde direction relative to the binary. The disc experiences the largest…
The star formation process in molecular clouds usually leads to the formation of multiple stellar systems, mostly binaries. Remaining disks around those stars may be located around individual stars (circumstellar disks) or around the entire…
The recent discoveries of circumbinary planets by $\it Kepler$ raise questions for contemporary planet formation models. Understanding how these planets form requires characterizing their formation environment, the circumbinary…
We report on the long-term variability of the Be/X-ray binary LS I +61 235/RX J0146.9+6121. New optical spectroscopic and infrared photometric observations confirm the presence of global one-arm oscillations in the circumstellar disc of the…
We report on the long-term average spin period, rate of change of spin period and X-ray luminosity during outbursts for 42 Be X-ray binary systems in the Small Magellanic Cloud. We also collect and calculate parameters of each system and…
Be stars are rapidly rotating, with angular frequency around $0.7-0.8$ of their Keplerian break up frequency, as a result of significant accretion during the earlier stellar evolution of a companion star. Material from the equator of the Be…