Correlated V/R and infrared photometric variations in the Be/X-ray binary LS I +61° 235/RX J0146.9+6121     

P. Reig  I. Negueruela  M. J. Coe  J. Fabregat  A. E. Tarasov  R. K. Zamanov 《Monthly notices of the Royal Astronomical Society》2000,317(1):205-210

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-armed oscillations in the circumstellar disc of the Be star, and allow us to derive a V R band quasi-period of 1240±30 d. Pronounced shell events, reminiscent of the spectacular variations in Be stars, are also seen. We have found that the J , H and K infrared photometric bands vary in correlation with the spectroscopic V R variations, implying that the one-armed disc oscillations are prograde. The effect of the oscillations is not only seen in the H α line but is also seen in the He  i λ 6678 and Paschen lines. As these lines are formed at different radii in the equatorial disc of the Be star, such effects confirm the global nature of the perturbation. The Keplerian disc has been found to be denser than the average for a sample of isolated Be stars, which may be indicative of some kind of interaction with the compact companion. Finally, from a Rossi X-ray Timing Explorer observation we derive a spin period of the neutron star of 1404.5±0.5 s.  相似文献   

Optical and X-ray variability of two Small Magellanic Cloud X-ray binary pulsars – SXP46.6 and SXP6.85     

K. E. McGowan  M. J. Coe  M. P. E. Schurch  R. H. D. Corbet  J. L. Galache  A. Udalski 《Monthly notices of the Royal Astronomical Society》2008,384(2):821-826

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Long-term properties of accretion discs in X-ray binaries – II. Stability of radiation-driven warping     

W. I. Clarkson  P. A. Charles  M. J. Coe  S. Laycock 《Monthly notices of the Royal Astronomical Society》2003,343(4):1213-1223

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Optical counterparts to four X-ray sources in the Small Magellanic Cloud     

W. R. T. Edge  M. J. Coe 《Monthly notices of the Royal Astronomical Society》2003,338(2):428-432

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X-Ray and optical observations of XTE J0052−723: a transient Be/X-ray pulsar in the Small Magellanic Cloud     

S. Laycock  R. H. D. Corbet  M. J. Coe  F. E. Marshall  C. Markwardt  W. Edge 《Monthly notices of the Royal Astronomical Society》2003,339(2):435-441

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Long-term properties of accretion discs in X-ray binaries – I. The variable third period in SMC X-1     

W. I. Clarkson  P. A. Charles  M. J. Coe  S. Laycock  M. D. Tout  C. A. Wilson 《Monthly notices of the Royal Astronomical Society》2003,339(2):447-454

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Simulating the surface waters of the Amazon River basin: impacts of new river geomorphic and flow parameterizations     

Michael T. Coe  Marcos H. Costa  Erica A. Howard 《水文研究》2008,22(14):2542-2553

This paper describes the impacts of new river geomorphic and flow parameterizations on the simulated surface waters dynamics of the Amazon River basin. Three major improvements to a hydrologic model are presented: (1) the river flow velocity equation is expanded to be dependent on river sinuosity and friction in addition to gradient forces; (2) equations defining the morphological characteristics of the river, such as river height, width and bankfull volume, are derived from 31 622 measurements of river morphology and applied within the model; (3) 1 km resolution topographic data from the Shuttle Radar Topography Mission (SRTM) are used to provide physically based fractional flooding of grid cells from a statistical representation of sub‐grid‐scale floodplain morphology. The discharge and floodplain inundation of the Amazon River is simulated for the period 1968–1998, validated against observations, and compared with results from a previous version of the model. These modifications result in considerable improvement in the simulations of the hydrological features of the Amazon River system. The major impact is that the average wet‐season flooded area on the Amazon mainstem for the period 1983–1988 is now within 5% of satellite‐derived estimates of flooded area, whereas the previous model overestimates the flooded area by about 80%. The improvements are a consequence of the new empirical river geomorphologic functions and the SRTM topography. The new formulation of the flow velocity equation results in increased river velocity on the mainstem and major tributaries and a better correlation between the mean monthly simulated and observed discharge. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

AX J0049.4−7323: a close look at a neutron star interacting with a circumstellar disc     

M. J. Coe  W. R. T. Edge 《Monthly notices of the Royal Astronomical Society》2004,350(2):756-760

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Radio observations of X-ray pulsators     

M. J. Coe  G. J. Gavin 《Astrophysics and Space Science》1983,89(1):169-172

A detailed search has been performed at 10.7 GHz for any pulsed radio emission from four X-ray pulsators (A0535+26, X Persei, AE Aquarii and H2252-035). The results obtained indicate no radio emission-pulsed or otherwise is present at a level of ≥ 50 mJy (two standard deviations upper limit). This value is considerably more sensitive than the previous studies carried out on these sources and presents problems in the understanding of compact, magnetised stellar objects.  相似文献   

Optical studies of two Large Magellanic Cloud X-ray transients: RX J0544.1–7100 and RX J0520.5–6932     

M.J. Coe  I. Negueruela  D.A.H. Buckley  N.J. Haigh  S.G.T. Laycock 《Monthly notices of the Royal Astronomical Society》2001,324(3):623-627

We report observations that confirm the identities of the optical counterparts to the transient sources RX J0544.1–7100 and RX J0520.5–6932 . The counterparts are suggested to be B-type stars. Optical data from the observations carried out at ESO and SAAO, together with results from the OGLE data base, are presented. In addition, X-ray data from the RXTE All-Sky Monitor are investigated for long-term periodicities. A strong suggestion for a binary period of 24.4 d is seen in RX J0520.5–6932 from the OGLE data.  相似文献