A normal and superoutburst study of the eclipsing SU UMa star: DV Ursae Majoris     

Daisaku Nogami  †  Taichi Kato  Hajime Baba  Rudolf Novák  J. J. Lockley  M. Somers 《Monthly notices of the Royal Astronomical Society》2001,322(1):79-84

We report on time-resolved photometry carried out during the 1995 short outburst and the 1997 long outburst in the eclipsing dwarf nova DV UMa. The revised orbital period is 0.0858526172 (67) d. We detected gigantic superhumps with an amplitude of ∼0.6 mag in the mid-phase of the 1997 outburst, revealing the SU UMa nature of DV UMa. The superhump period is 0.0887 (4) d. The superhumps became less clear during the late phase of the superoutburst, and we found two possible periods of 0.0885 (15) and 0.0764 (15). During both outbursts, the eclipse was wide and shallow near the maximum, and then became narrower and deeper, which is qualitatively well explained by the current disc instability theory.  相似文献   

Extremely weak reflection features in the X-ray spectrum of XTE J1118+480: possible evidence for X-ray-emitting jets?     

J. M. Miller  D. R. Ballantyne  A. C. Fabian  W. H. G. Lewin 《Monthly notices of the Royal Astronomical Society》2002,335(4):865-870

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The bivariate brightness function of galaxies and a demonstration of the impact of surface brightness selection effects on luminosity function estimations     

Nicholas Cross  Simon P. Driver 《Monthly notices of the Royal Astronomical Society》2002,329(3):579-587

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Reflection at large distance from the central engine in Seyferts     

Julien Malzac  Pierre-Olivier Petrucci 《Monthly notices of the Royal Astronomical Society》2002,336(4):1209-1216

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Early-type galaxy distances from the Fundamental Plane and surface brightness fluctuations   总被引：1，自引：0，他引：1  

John P.Blakeslee  John R.Lucey  John L.Tonry  Michael J.Hudson  Vijay K.Narayanan  Brian J.Barris 《Monthly notices of the Royal Astronomical Society》2002,330(2):443-457

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Spectroscopy and orbit determination of the chromospherically active double-lined binary system HD 163621 = V835 Herculis     

R. F. Griffin  F. C. Fekel  M. D. Morton  R. E. Fried 《Journal of Astrophysics and Astronomy》1994,15(3):309-319

HD 163621 is a double-lined spectroscopic binary in a circular orbit whose period is 3.3 days. Spectral classification of the components has proved difficult, but current results of K0 V and late K V are reasonably consistent with our best model of the system, which has spectral types of G8V and K7V. The object shows photometric variability and chromospheric activity and is therefore a member of the BY Draconis class of variables. The minimum masses are quite small, 0.10 and 0.07 M⊙ for the primary and secondary, respectively, suggesting an orbital inclination of about 30°. The system is synchronously rotating. Its distance is estimated to be 31 pc, which makes it an excellent candidate for a trigonometric parallax determination. Kitt Peak National Observatory, [U.S.] National Optical Astronomy Observatories, operated by AURA Inc. under contract with the [U.S.] National Science Foundation.  相似文献   

The short-period supersoft source in M31     

A. R. King  J. P. Osborne  K. Schenker 《Monthly notices of the Royal Astronomical Society》2002,329(2):L43-L46

We show that the recently discovered short period supersoft source in M31 is probably a progenitor of a magnetic cataclysmic variable (CV). The white dwarf spins asynchronously because of the current high accretion rate. However its fieldstrength is typical of an AM Herculis system, which is what it will ultimately become. We discuss the relevance of this system to CV evolution, and its relation to some particular CVs with special characteristics.  相似文献   

Tidally distorted accretion discs in binary stars     

G. I.Ogilvie 《Monthly notices of the Royal Astronomical Society》2002,330(4):937-949

The non-axisymmetric features observed in the discs of dwarf novae in outburst are usually considered to be spiral shocks, which are the non-linear relatives of tidally excited waves. This interpretation suffers from a number of problems. For example, the natural site of wave excitation lies outside the Roche lobe, the disc must be especially hot, and most treatments of wave propagation do not take into account the vertical structure of the disc.
In this paper I construct a detailed semi-analytical model of the non-linear tidal distortion of a thin, three-dimensional accretion disc by a binary companion on a circular orbit. The analysis presented here allows for vertical motion and radiative energy transport, and introduces a simple model for the turbulent magnetic stress. The   m =2  inner vertical resonance has an important influence on the amplitude and phase of the tidal distortion. I show that the observed patterns find a natural explanation if the emission is associated with the tidally thickened sectors of the outer disc, which may be irradiated from the centre. According to this hypothesis, it may be possible to constrain the physical parameters of the disc through future observations.  相似文献   

Phase-resolved X-ray spectroscopy of the millisecond pulsar SAX J1808.4−3658     

MarekGierlin´ski  ChrisDone  DidierBarret 《Monthly notices of the Royal Astronomical Society》2002,331(1):141-153

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Spectral analysis of water vapour in cool stars     

Hugh R. A.Jones  YakivPavlenko  SerenaViti  JonathanTennyson 《Monthly notices of the Royal Astronomical Society》2002,330(3):675-684

M-star spectra, at wavelengths beyond 1.35 μm, are dominated by water vapour, yet terrestrial water vapour makes it notoriously difficult to obtain accurate measurement from ground-based observations. We have used the short-wavelength spectrometer on the Infrared Space Observatory at four wavelength settings to cover the  2.5–3.0 μm  region for a range of M stars. The observations show a good match with previous ground-based observations and with synthetic spectra based on the Partridge & Schwenke line list, although not with the SCAN line list. We have used a least-squared minimization technique to systematically find best-fitting parameters for the sample of stars. The temperatures that we find indicate a relatively hot temperature scale for M dwarfs. We consider that this could be a consequence of problems with the Partridge & Schwenke line list which leads to synthetic spectra predicting water bands that are too strong for a given temperature. Such problems need to be solved in the next generation of water vapour line lists, which will extend the calculation of water vapour to higher energy levels with the good convergence necessary for reliable modelling of hot water vapour. Then water bands can assume their natural role as the primary tool for the spectroscopic analysis of M stars.  相似文献