Using the population synthesis code StarTrack we construct the first synthetic X-ray binary populations for direct comparison with the X-ray luminosity function (XLF) of NGC 1569 observed with Chandra. Our main goal is to examine whether it is possible to reproduce the XLF shape with our models, given the current knowledge for the star-formation history of this starburst galaxy. We thus produce...

We present new optical and infrared (IR) observations of Cir X-1 taken near apastron. Both sets of spectra show asymmetric emission lines. Archival optical observations show that an asymmetric Hα emission line has been in evidence for the past twenty years, although the shape of the line has changed significantly. We present an eccentric (e ∼ 0.7–0.9) low mass binary model, where the system con...

Hills (1988) predicted that runaway stars could be accelerated to velocities larger than 1000 km s by dynamical encounters with the supermassive black hole (SMBH) in the Galactic center. The recently discovered hypervelocity star SDSS J090745.0+024507 (hereafter HVS) is escaping the Galaxy at high speed and could be the first object in this class. With the measured radial velocity and the estim...

In this paper we present multi-epoch observations of the pre-main sequence binary HK Ori. These data have been drawn from the EXPORT database and are complemented by high quality spectro-astrometric data of the system. The spectroscopic data appear to be very well represented by a combination of an A dwarf star spectrum superposed on a (sub-)giant Gtype spectrum. The radial velocity of the syst...

Some massive binaries should contain energetic pulsars which inject relativistic leptons from their inner magnetospheres and/or pulsar wind regions. If the binary system is compact enough, then these leptons can initiate inverse Compton (IC) e pair cascades in the anisotropic radiation field of a massive star. γ-rays can be produced in the IC cascade during its development in a pulsar wind regi...

SuperWASP is a wide angle survey for transiting hot-Jupiter exoplanets around bright (V<13) solar-type stars. Lightcurves for millions of stars with a few thousand observations per star are available in the SuperWASP archive. We report the results of a search for periodic variable subdwarf stars in the data from the 2004 observing season. A Fourier transform of the SuperWASP lightcurve for Ball...

High-speed spectroscopy of two pulsating subdwarf B stars, KPD2109+4401 and PB8783, is presented. Radial motions are detected with the same frequencies as reported from photometric observations and with amplitudes of ∼ 2 kms in two or more independent modes. These represent the first direct observations of surface motion due to multimode non-radial oscillations in subdwarf B stars. In the case ...

Burst-only sources are X–ray sources showing up only during short bursts but with no persistent emission (at least with the monitoring instrument which led to their discovery). These bursts have spectral characteristics consistent with thermonuclear (type I) burst from the neutron star surface, linking burst-only sources to neutron star X–ray binary transients. We have carried out a series of s...

A spectroscopic analysis of the G-star located at the centre of Abell 35 leads to a surface gravity log g= 3.7±0.5 and an effective temperature T eff = 5300 ± 200 K, which are typical of a G8IV spectral type. We estimate a projected rota-tional velocity of 55 ± 10 km s −1 and deduce a radius 1.5 ≤ R G ≤ 3.5R in agreement with the subgiant luminosity class: the star is rapidly rotating, near the...