Related papers: The spotty donor star in the X-ray transient Cen X…
We present ESO-NTT low resolution spectroscopy of the neutron star X-ray transient Cen X-4 in quiescence over a complete orbital cycle. Our data reveal the presence of a K3-7 V companion which contributes 63% to the 5600-6900A flux and…
We present a study of the neutron star X-Ray Transient Cen X-4. Our aim is to look for any evidence of irradiation of the companion with a detailed analysis of its radial velocity curve, relative contribution of the donor star and Doppler…
We present high and intermediate resolution spectroscopy of the X-ray nova Centaurus X-4 during its quiescent phase. Our analysis of the absorption features supports a K3-K5V spectral classification for the companion star, which contributes…
We present the first determination of the proper motion of the neutron star low mass X-ray binary {Cen X-4} measured from relative astrometry of the secondary star using optical images at different epochs. We determine the Galactic space…
We present the results of ellipsoidal light curve modeling of the low mass X-ray binary Cen X-4 in order to constrain the inclination of the system and mass of the neutron star. Near-IR photometric monitoring was performed in May 2008 over…
We intended to measure the radial velocity curve of the supergiant companion to the eclipsing high mass X-ray binary pulsar EXO1722-363 and hence determine the stellar masses of the components. We used a set of archival K$_{\rm s}$-band…
We report near-infrared observations of the supergiant donor to the eclipsing high mass X-ray binary pulsar IGR J18027-2016. We aim to determine its spectral type and measure its radial velocity curve and hence determine the stellar masses…
We report high-resolution optical spectroscopy of the low-mass X-ray binary V395 Car/2S 0921-630 obtained with the MIKE echelle spectrograph on the Magellan-Clay telescope. Our spectra are obtained near superior conjunction of the mass…
We present the results of a spectroscopic monitoring campaign of the OB-star companions to the eclipsing X-ray pulsars SMC X-1, LMC X-4 and Cen X-3. High-resolution optical spectra obtained with UVES on the ESO Very Large Telescope are used…
Chandra or XMM-Newton observations of quiescent low-mass X-ray binaries can provide important constraints on the equation of state of neutron stars. The mass and radius of the neutron star can potentially be determined from fitting a…
We describe sophisticated new Bayesian analysis methods that make it possible to estimate quickly the masses and radii of rapidly rotating, oblate neutron stars by fitting oblate-star waveform models to energy-resolved observations of the…
Using phase resolved spectroscopic observations obtained with the Ultraviolet and Visual Echelle Spectrograph on ESO's Kueyen Very Large Telescope supplemented by spectroscopic observations obtained with the Boller and Chivens Spectrograph…
We present near-infrared (NIR) broadband (0.80--2.42 $\mu$m) spectroscopy of two low mass X-ray binaries: V404 Cyg and Cen X-4. One important parameter required in the determination of the mass of the compact objects in these systems is the…
We consider the production of 2.22 MeV radiation resulting from the capture of neutrons in the atmosphere of the secondary in an X-ray binary system, where the neutrons are produced in the accretion disk around the compact primary star and…
Cygnus X-2 is one of the brightest and longest known X-ray sources. We present high resolution optical spectroscopy of Cyg X-2 obtained over 4 years which gives an improved mass function of 0.69 +/- 0.03 Msun (1 sigma error). In addition,…
We discuss millisecond period brightness oscillations and surface atomic spectral lines observed during type I X-ray bursts from a neutron star in a low mass X-ray binary system. We show that modeling of these phenomena can constrain models…
We interpret the observed radial-velocity curve of the optical star in the low-mass X-ray binary 2S 0921-630 using a Roche model, taking into account the X-ray heating of the optical star and screening of X-rays coming from the relativistic…
We present the first detection of the mass donor star in the prototype X-ray binary Scorpius X-1. Phase resolved spectroscopy revealed narrow emission lines components from the irradiated secondary star. Radial velocity fits to the Bowen…
We report on spectral and intensity variability analysis from a Chandra/ACIS-S observation of the transient, type-I X-ray bursting low-mass X-ray binary Cen X-4. The quiescent X-ray spectrum during this observation is statistically…
Bursting X-ray binaries in globular clusters are ideal sources for measuring neutron star masses and radii, and hence, for determining the equation of state of cold, ultradense matter. We use time-resolved spectroscopic data from EXO…