We argue that the bursting, transient X-ray source GRO J1744-28 is a binary consisting of a very low-mass (M ≈ 0.2M⊙), highly evolved giant star that is transferring mass by Roche lobe overflow onto a high-mass (M ≈ 1.8M⊙) neutron star. We explore a picture in which the bursts are due to thermonuclear flashes in matter that has accreted onto the neutron star. We attribute the unusually hard spe...

Recent observations of PSR J0045-7319, a radio pulsar in a close eccentric orbit with a massive main sequence B-star companion, indicate that the system’s orbital period is decreasing on a timescale ∼ 5x10 years (Kaspi et al. 1996). Timing observations of PSR J0045-7319 also indicate that the B-star is rotating rapidly, perhaps close to its breakup rotation rate (Lai et al. 1995, Kaspi et al. 1...

The accretion of ≈ 0.1 – 1 M⊙ of material by a neutron star through Roche lobe overflow of its companion or through white-dwarf/neutron-star coalescence in a low mass binary system could be enough to exceed the critical mass of a neutron star and trigger its collapse to a black hole, leading to the production of a short gamma-ray burst (SGRB). In this model, SGRBs would often be found in early-...

Recent discovery of the afterglow emission from short gamma-ray bursts suggests that binary neutron star or black hole-neutron star binary mergers are the likely progenitors of these short bursts. The accretion of neutron star material and its subsequent ejection by the central engine implies a neutron-rich outflow. We consider here a neutron-rich relativistic jet model of short bursts, and inv...

Recent discovery of the afterglow emission from short gamma-ray bursts suggests that binary neutron star or black hole-neutron star binary mergers are the likely progenitors of these short bursts. The accretion of neutron star material and its subsequent ejection by the central engine implies a neutron-rich outflow. We consider here a neutron-rich relativistic jet model of short bursts, and inv...

Recent observations of PSR J0045-7319, a radio pulsar in a close eccentric orbit with a massive main sequence B-star companion, indicate that the system’s orbital period is decreasing on a timescale ∼ 5x10 years (Kaspi et al. 1996). Timing observations of PSR J0045-7319 also indicate that the B-star is rotating rapidly, perhaps close to its breakup rotation rate (Lai et al. 1995, Kaspi et al. 1...

KIC 2856960 is a star in the Kepler field which was observed by Kepler for 4 years. It shows the primary and secondary eclipses of a close binary of period 0.258 d as well as complex dipping events that last for about 1.5 d at a time and recur on a 204 d period. The dips are thought to result when the close binary passes across the face of a third star. In this paper we present an attempt to mo...

We present spectra of the pulsating sdB star KPD 1930+2752 which confirm that this star is a binary. The radial velocities measured from the Hα and HeI 6678Å spectral lines vary sinusoidally with the same period (2 h 17 m) as the ellipsoidal variability seen byBilì eres et al. (2000). The amplitude of the orbital motion (349.3±2.7 km s −1) combined with the canonical mass for sdB stars (0.5M ⊙)...

Be stars are rapidly spinning B stars surrounded by an outflowing disc of gas in Keplerian rotation. Be star/X-ray binary systems contain a Be star and a neutron star. They are found to have non-zero eccentricities and there is evidence that some systems have a misalignment between the spin axis of the star and the spin axis of the binary orbit. The eccentricities in these systems are be caused...

We study the effect of rotation on the excitation of internal oscillation modes of a star by the external gravitational potential of its companion. Unlike the nonrotating case, there are difficulties with the usual mode decomposition for rotating stars because of the asymmetry between modes propagating in the direction of rotation and those propagating opposite to it. For an eccentric binary sy...