The faint end of the galaxy luminosity function     

Neil Trentham  R. Brent Tully 《Monthly notices of the Royal Astronomical Society》2002,335(3):712-732

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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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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   

The λ Bootis phenomenon: interaction between a star and a diffuse interstellar cloud     

Inga Kamp  Ernst Paunzen 《Monthly notices of the Royal Astronomical Society》2002,335(2):L45-L49

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Elastic solutions for stresses in a transversely isotropic half‐space subjected to three‐dimensional buried parabolic rectangular loads     

Cheng‐Der Wang  Jyh‐Jong Liao 《国际地质力学数值与分析法杂志》2002,26(14):1449-1476

In many areas of engineering practice, applied loads are not uniformly distributed but often concentrated towards the centre of a foundation. Thus, loads are more realistically depicted as distributed as linearly varying or as parabola of revolution. Solutions for stresses in a transversely isotropic half‐space caused by concave and convex parabolic loads that act on a rectangle have not been derived. This work proposes analytical solutions for stresses in a transversely isotropic half‐space, induced by three‐dimensional, buried, linearly varying/uniform/parabolic rectangular loads. Load types include an upwardly and a downwardly linearly varying load, a uniform load, a concave and a convex parabolic load, all distributed over a rectangular area. These solutions are obtained by integrating the point load solutions in a Cartesian co‐ordinate system for a transversely isotropic half‐space. The buried depth, the dimensions of the loaded area, the type and degree of material anisotropy and the loading type for transversely isotropic half‐spaces influence the proposed solutions. An illustrative example is presented to elucidate the effect of the dimensions of the loaded area, the type and degree of rock anisotropy, and the type of loading on the vertical stress in the isotropic/transversely isotropic rocks subjected to a linearly varying/uniform/parabolic rectangular load. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

On the evolution of the nova-like variable AE Aquarii     

P. J. Meintjes 《Monthly notices of the Royal Astronomical Society》2002,336(1):265-275

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Near-infrared and optical emission-line structure of the Keyhole Nebula in NGC 3372     

NathanSmith † 《Monthly notices of the Royal Astronomical Society》2002,331(1):7-12

Narrow-band infrared and optical images of the Keyhole Nebula in NGC 3372 reveal which structures are caused by extinction, and show the underlying morphology of photoionized and shock-excited gas. Dark clouds conspire with ionized gas to create the apparent keyhole shape, which is prominent at blue wavelengths and less apparent in the infrared. The  Pa β /H α   line ratio shows the spatial distribution of foreground extinction. The wavelength dependence of this extinction indicates a reddening law with   R ≈4.8  , different from the normal interstellar medium. This confirms previous estimates of reddening toward the Carina Nebula determined from stellar photometry, and reveals that the anomalous extinction is patchy and within the H  ii region. The morphology of the ionized gas is different from the extinction clouds; it shows an edge-on ionization front running NE to SW, with a limb-brightened indentation that forms the upper outline of the keyhole shape. A fast polar wind from η Carinae may have punctured the ionization front, since the indentation is directly along a projection of the polar axis of the star. This is supported by the morphology of shock-excited gas revealed by a high  [S  ii ]/H α   ratio. High-excitation gas emitting [O  iii ] and He  i has a smoother distribution. Molecular clumps in the region are also discussed.  相似文献   

Radial orbital anisotropy and the Fundamental Plane of elliptical galaxies     

C. Nipoti  P. Londrillo  L. Ciotti 《Monthly notices of the Royal Astronomical Society》2002,332(4):901-914

The existence of the Fundamental Plane imposes strong constraints on the structure and dynamics of elliptical galaxies, and thus contains important information on the processes of their formation and evolution. Here we focus on the relations between the Fundamental Plane thinness and tilt and the amount of radial orbital anisotropy: in fact, the problem of the compatibility between the observed thinness of the Fundamental Plane and the wide spread of orbital anisotropy admitted by galaxy models has often been raised. By using N -body simulations of galaxy models characterized by observationally motivated density profiles, and also allowing for the presence of live, massive dark matter haloes, we explore the impact of radial orbital anisotropy and instability on the Fundamental Plane properties. The numerical results confirm a previous semi-analytical finding (based on a different class of one-component galaxy models): the requirement of stability matches almost exactly the thinness of the Fundamental Plane. In other words, galaxy models that are radially anisotropic enough to be found outside the observed Fundamental Plane (with their isotropic parent models lying on the Fundamental Plane) are unstable, and their end-products fall back on the Fundamental Plane itself. We also find that a systematic increase of radial orbit anisotropy with galaxy luminosity cannot explain by itself the whole tilt of the Fundamental Plane, the galaxy models becoming unstable at moderately high luminosities: at variance with the previous case, their end-products are found well outside the Fundamental Plane itself. Some physical implications of these findings are discussed in detail.  相似文献   

The 69-μm forsterite band as a dust temperature indicator     

J. E.Bowey  M. J.Barlow  F. J.Molster  A. M.Hofmeister  C.Lee  C.Tucker  T.Lim  P. A. R.Ade  L. B. F. M.Waters 《Monthly notices of the Royal Astronomical Society》2002,331(1):L1-L6

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The X-ray spectrum of Cyg X-2     

C.Done  P. T.Z&#;ycki  D. A.Smith 《Monthly notices of the Royal Astronomical Society》2002,331(2):453-462

The spectra of disc accreting neutron stars generally show complex curvature, and individual components from the disc, boundary layer and neutron star surface cannot be uniquely identified. Here we show that much of the confusion over the spectral form derives from inadequate approximations for Comptonization and for the iron line. There is an intrinsic low-energy cut-off in Comptonized spectra at the seed photon energy. It is very important to model this correctly in neutron star systems as these have expected seed photon temperatures (from either the neutron star surface, inner disc or self-absorbed cyclotron) of ≈1 keV, clearly within the observed X-ray energy band. There is also reflected continuum emission which must accompany the observed iron line, which distorts the higher energy spectrum. We illustrate these points by a reanalysis of the Ginga spectra of Cyg X-2 at all points along its Z track, and show that the spectrum can be well fitted by models in which the low-energy spectrum is dominated by the disc, while the higher energy spectrum is dominated by Comptonized emission from the boundary layer, together with its reflected spectrum from a relativistically smeared, ionized disc.  相似文献