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Detection Of The Irradiated Donor In The Lmxbs 4u 1636-536 (=V801 Ara) And 4u 1735-444 (=V926 Sco), J. Casares, R. Cornelisse, D. Steeghs, P. A. Charles, R. I. Hynes, K. O'Brien, T. E. Strohmayer
Detection Of The Irradiated Donor In The Lmxbs 4u 1636-536 (=V801 Ara) And 4u 1735-444 (=V926 Sco), J. Casares, R. Cornelisse, D. Steeghs, P. A. Charles, R. I. Hynes, K. O'Brien, T. E. Strohmayer
Faculty Publications
Phase-resolved VLT spectroscopy of the bursting low-mass X-ray binaries 4U 1636-536/V801 Ara and 4U 1735-444/V926 Sco is presented. Doppler images of the N III λ4640 Bowen transition reveal compact spots which we attribute to fluorescent emission from the donor star and enable us to define a new set of spectroscopic ephemerides. We measure K em = 277 ± 22 and 226 ± 22 kms -1 from the N III spots in V801 Ara and V926 Sco, respectively, which represent strict lower limits to the radial velocity semi-amplitude of the donor stars. Our new ephemerides provide confirmation that light-curve maxima in …
Further Evidence For Variable Synchrotron Emission In Xte J1118+480 In Outburst, R. I. Hynes, E. L. Robinson, K. J. Pearson, D. M. Gelino, W. Cui, Y. Q. Xue, M. A. Wood, T. K. Watson, D. E. Winget, I. M. Silver
Further Evidence For Variable Synchrotron Emission In Xte J1118+480 In Outburst, R. I. Hynes, E. L. Robinson, K. J. Pearson, D. M. Gelino, W. Cui, Y. Q. Xue, M. A. Wood, T. K. Watson, D. E. Winget, I. M. Silver
Faculty Publications
We present simultaneous multicolor infrared and optical photometry of the black hole X-ray transient XTE Jill 8+480 during its short 2005 January outburst, supported by simultaneous X-ray observations. The variability is dominated by short timescales, ∼10 s, although a weak superhump also appears to be present in the optical. The optical rapid variations, at least, are well correlated with those in X-rays. Infrared JHKS photometry, as in the previous outburst, exhibits especially large-amplitude variability. The spectral energy distribution (SED) of the variable infrared component can be fitted with a power law of slope α = -0.78 ± 0.07, where Fν …
Multiwavelength Observations Of Exo 0748-676. I. Reprocessing Of X-Ray Bursts, R. I. Hynes, Keith Horne, K. O'Brien, C. A. Haswell, E. L. Robinson, A. R. King, P. A. Charles, K. J. Pearson
Multiwavelength Observations Of Exo 0748-676. I. Reprocessing Of X-Ray Bursts, R. I. Hynes, Keith Horne, K. O'Brien, C. A. Haswell, E. L. Robinson, A. R. King, P. A. Charles, K. J. Pearson
Faculty Publications
We present high time-resolution multi wavelength observations of X-ray bursts in the low-mass X-ray binary UY Vol. Strong reprocessed signals are present in the ultraviolet and optical, lagged and smeared with respect to the X-rays. The addition of far-ultraviolet coverage for one burst allows much tighter constraints on the temperature and geometry of the reprocessing region than previously possible. A blackbody reprocessing model for this burst suggests a rise in temperatures during the burst from 18,000 to 35,000 K and an emitting area comparable to that expected for the disk and/or irradiated companion star. The lags are consistent with those …
Multiwavelength Observations Of Exo 0748-676. Ii. Emission-Line Behavior, K. J. Pearson, R. I. Hynes, D. Steeghs, P. G. Jonker, C. A. Haswell, A. R. King, K. O'Brien, G. Nelemans, M. Méndez
Multiwavelength Observations Of Exo 0748-676. Ii. Emission-Line Behavior, K. J. Pearson, R. I. Hynes, D. Steeghs, P. G. Jonker, C. A. Haswell, A. R. King, K. O'Brien, G. Nelemans, M. Méndez
Faculty Publications
We present optical and ultraviolet spectra, light curves, and Doppler tomograms of the low-mass X-ray binary EXO 0748-676. Using an extensive set of 15 emission-line tomograms, we show that, along with the usual emission from the stream and "hot spot," there is extended nonaxisymmetric emission from the disk rim. Some of the emission and Ha and Hβ absorption features lend weight to the hypothesis that part of the stream overflows the disk rim and forms a two phase medium. The data are consistent with a 1.35 M ⊙ neutron star with a main-sequence companion and hence a mass ratio q …
Global Optical/Infrared-X-Ray Correlations In X-Ray Binaries: Quantifying Disc And Jet Contributions, D. M. Russell, R. P. Fender, R. I. Hynes, C. Brocksopp, J. Homan, P. G. Jonker, M. M. Buxton
Global Optical/Infrared-X-Ray Correlations In X-Ray Binaries: Quantifying Disc And Jet Contributions, D. M. Russell, R. P. Fender, R. I. Hynes, C. Brocksopp, J. Homan, P. G. Jonker, M. M. Buxton
Faculty Publications
The optical/near-infrared (OIR) region of the spectra of low-mass X-ray binaries (XBs) appears to lie at the intersection of a variety of different emission processes. In this paper we present quasi-simultaneous OIR-X-ray observations of 33 XBs in an attempt to estimate the contributions of various emission processes in these sources, as a function of X-ray state and luminosity. A global correlation is found between OIR and X-ray luminosity for low-mass black hole candidate XBs (BHXBs) in the hard X-ray state, of the form L OIR ∝ L X0.6, This correlation holds over eight orders of magnitude in L X and …
Vw Hyi: Optical Spectroscopy And Doppler Tomography, Amanda J. Smith, Carole A. Haswell, Robert I. Hynes
Vw Hyi: Optical Spectroscopy And Doppler Tomography, Amanda J. Smith, Carole A. Haswell, Robert I. Hynes
Faculty Publications
We present high-quality optical spectroscopy of the SU UMa-subtype dwarf nova, VW Hyi taken while the system was in quiescence. An S-wave is executed by the emission cores of the hydrogen Balmer lines and by the emission lines of He I, Ca II, Fe II and He II. Using Doppler tomography, we show it originates in the accretion stream-disc impact region. The He II emission is strongly phase-dependent, suggesting it originates exclusively within a hot cavity at the initial impact. We map the ionization structure of the stream-disc interaction region. One possible interpretation of this is that the Balmer hotspot …
Numerical Simulations Of The Onset And Stability Of Dynamical Mass Transfer In Binaries, Mario C.R. D'Souza, Patrick M. Motl, Joel E. Tohline, Juhan Frank
Numerical Simulations Of The Onset And Stability Of Dynamical Mass Transfer In Binaries, Mario C.R. D'Souza, Patrick M. Motl, Joel E. Tohline, Juhan Frank
Faculty Publications
Hydrodynamical simulations of semidetached, polytropic binary stars are presented in an effort to study the onset and stability of dynamical mass transfer events. Initial, synchronously rotating equilibrium models are constructed using a self-consistent field technique and then evolved with an Eulerian hydrodynamics code in a fully self-consistent manner. We describe code improvements introduced over the past few years that permit us to follow dynamical mass transfer events through more than 30 orbits. Mass transfer evolutions are presented for two different initial configurations: a dynamically unstable binary with initial mass ratio (donor/accretor) q 0 = 1.3 that leads to a complete …