Three-dimensional numerical simulation of gaseous flow structure in semidetached binaries     

D. V. Bisikalo  A. A. Boyarchuk  V. M. Chechetkin  O. A. Kuznetsov  & D. Molteni 《Monthly notices of the Royal Astronomical Society》1998,300(1):39-48

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The 1996 outburst of GRO J1655–40: the challenge of interpreting the multiwavelength spectra     

R. I. Hynes  C. A. Haswell  C. R. Shrader  W. Chen  Keith Horne  E. T. Harlaftis  K. O'Brien  C. Hellier  & R. P. Fender 《Monthly notices of the Royal Astronomical Society》1998,300(1):64-82

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Dynamical determination of the quadrupole mass moment of a white dwarf     

Lorenzo Iorio 《Astrophysics and Space Science》2007,310(1-2):73-76

In this paper we dynamically determine the quadrupole mass moment Q of the magnetic white dwarf WD 0137-349 by looking for deviations from the third Kepler law induced by Q in the orbital period of the recently discovered brown dwarf moving around it in a close 2-hr orbit. It turns out that a purely Newtonian model for the orbit of WD 0137-349B, assumed circular and equatorial, is adequate, given the present-day accuracy in knowing the orbital parameters of such a binary system. Our result is Q=(−1.5±0.9)×10⁴⁷ kg m² for i=35 deg. It is able to accommodate the 3-sigma significant discrepancy of (1.0±0.3)×10⁻⁸ s⁻² between the inverse square of the phenomenologically determined orbital period and the inverse square of the calculated Keplerian one. The impact of i, for which an interval Δ i of possible values close to 35 deg is considered, is investigated as well.  相似文献   

On the ultracompact nature of 4U 1822−000     

T. Shahbaz  C. A. Watson  H. Hernandez-Peralta 《Monthly notices of the Royal Astronomical Society》2007,376(4):1886-1888

We report the discovery of a periodic modulation in the optical lightcurve of the candidate ultracompact X-ray binary 4U 1822−000. Using time-resolved optical photometry taken with the William Herschel Telescope we find evidence for a sinusoidal modulation with a semi-amplitude of 8 per cent and a period of 191 min, which is most likely close to the true orbital period of the binary. Using the van Paradijs & McClintock relation for the absolute magnitude and the distance modulus allowing for interstellar reddening, we estimate the distance to 4U 1822−000 to be 6.3 kpc. The long orbital period casts severe doubts on the ultracompact nature of 4U 1822−000.  相似文献   

The population of AM CVn stars from the Sloan Digital Sky Survey     

G. H. A. Roelofs  G. Nelemans  P. J. Groot 《Monthly notices of the Royal Astronomical Society》2007,382(2):685-692

The AM Canum Venaticorum (AM CVn) stars are rare interacting white dwarf binaries, whose formation and evolution are still poorly known. The Sloan Digital Sky Survey provides, for the first time, a sample of six AM CVn stars (out of a total population of 18) that are sufficiently homogeneous that we can start to study the population in some detail.
We use the Sloan sample to 'calibrate' theoretical population synthesis models for the space density of AM CVn stars. We consider optimistic and pessimistic models for different theoretical formation channels, which yield predictions for the local space density that are more than two orders of magnitude apart. When calibrated with the observations, all models give a local space density  ρ₀= 1–3 × 10⁻⁶ pc⁻³  , which is lower than expected.
We discuss the implications for the formation of AM CVn stars, and conclude that at least one of the dominant formation channels (the double-degenerate channel) has to be suppressed relative to the optimistic models. In the framework of the current models this suggests that the mass transfer between white dwarfs usually cannot be stabilized. We furthermore discuss evolutionary effects that have so far not been considered in population synthesis models, but which could be of influence for the observed population. We finish by remarking that, with our lower space density, the expected number of Galactic AM CVn stars resolvable by gravitational-wave detectors like the Laser Interferometer Space Antenna ( LISA ) should be lowered from current estimates, to about 1000 for a mission duration of 1 yr.  相似文献   

The space density of cataclysmic variables: constraints from the ROSAT North Ecliptic Pole survey     

M. L. Pretorius  C. Knigge  D. O'Donoghue  J. P. Henry  I. M. Gioia  C. R. Mullis 《Monthly notices of the Royal Astronomical Society》2007,382(3):1279-1288

We use the ROSAT North Ecliptic Pole (NEP) survey to construct a small, but purely X-ray flux-limited sample of cataclysmic variable stars (CVs). The sample includes only four systems, two of which (RX J1715.6+6856 and RX J1831.7+6511) are new discoveries. We present time-resolved spectroscopy of the new CVs and measure orbital periods of 1.64 ± 0.02 and 4.01 ± 0.03 h for RX J1715.6+6856 and RX J1831.7+6511, respectively. We also estimate distances for all the CVs in our sample, based mainly on their apparent brightness in the infrared. The space density of the CV population represented by our small sample is  1.1^+2.3_−0.7× 10⁻⁵ pc⁻³  . We can also place upper limits on the space density of any subpopulation of CVs too faint to be included in the NEP survey. In particular, we show that if the overall space density of CVs is as high as  2 × 10⁻⁴ pc⁻³  (as has been predicted theoretically), the vast majority of CVs must be fainter than   L _X≃ 2 × 10²⁹ erg s⁻¹  .  相似文献   

An alternative to common envelope evolution     

Martin E. Beer  Lynnette M. Dray  rew R. King  Graham A. Wynn 《Monthly notices of the Royal Astronomical Society》2007,375(3):1000-1008

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Newly discovered cataclysmic variables from the INT/WFC photometric Hα survey of the northern Galactic plane     

A. R. Witham  C. Knigge  A. Aungwerojwit  J. E. Drew  B. T. Gänsicke  R. Greimel  P. J. Groot  G. H. A. Roelofs  D. Steeghs  P. A. Woudt 《Monthly notices of the Royal Astronomical Society》2007,382(3):1158-1168

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Outbursts of EX Hydrae revisited     

N. Mhlahlo  D. A. H. Buckley  V. S. Dhillon  S. B. Potter  B. Warner  P. A. Woudt 《Monthly notices of the Royal Astronomical Society》2007,380(1):353-364

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SW Sextantis stars: the dominant population of cataclysmic variables with orbital periods between 3 and 4 h     

P. Rodríguez-Gil  B. T. Gänsicke  H.-J. Hagen  S. Araujo-Betancor  A. Aungwerojwit  C. Allende Prieto  D. Boyd  J. Casares  D. Engels  O. Giannakis  E. T. Harlaftis  J. Kube  H. Lehto  I. G. Martínez-Pais  R. Schwarz  W. Skidmore  A. Staude  M. A. P. Torres 《Monthly notices of the Royal Astronomical Society》2007,377(4):1747-1762

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