Post-glitch relaxation in pulsars     

P. B. Jones 《Monthly notices of the Royal Astronomical Society》2002,335(3):733-740

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Radar observations of Itokawa in 2004 and improved shape estimation     

Steven J. Ostro  Lance A. M. Benner  Christopher Magri  Jon D. Giorgini  Randy Rose  Raymond F. Jurgens  Donald K. Yeomans  Alice A. Hine  Michael C. Nolan  Daniel J. Scheeres  Stephen B. Broschart  Mikko Kaasalainen  Jean‐Luc Margot 《Meteoritics & planetary science》2005,40(11):1563-1574

Abstract— We present June 2004 radar images of asteroid 25143 Itokawa (1998 SF36) that improve upon the longitude‐latitude coverage of images obtained in 2001 by Ostro et al. (2004) and use the 2001–2004 data to refine that paper's constraints on Itokawa's shape. The 2004 images, the first of the asteroid's southern side, look distinctly different from the 2001 images, revealing leading edges that are much more curved and rugged than the nearly convex leading edges seen at northern latitudes in 2001. Itokawa is shaped like a slightly asymmetrical, bent, lumpy ellipsoid with dimensions along the principal axes within 10% of 594 times 320 times 288 m. To illustrate the uncertainty space associated with shape reconstruction from images with suboptimal orientational coverage, we present two alternative three‐dimensional models of the object.  相似文献   

Profiles of spectral lines of an accretion ring around a Kerr black hole     

J. L. Zhang  S. P. Xiang  J. F. Lu 《Astrophysics and Space Science》1985,113(1):181-187

Profiles of spectral lines emitted from an accretion ring around an object with strong gravitational field should be affected by Doppler shift, gravitational redshift, and deflection of light. Taking these effects into account, precise line profile of a Keplerian ring around a Kerr black hole for a distant observer is obtained by solving the kinetic equation of photons.  相似文献   

Contact Binaries: A Study of the Proximity Effects and Gravity Darkening Based on Kopal’s Fourier Method     

P. G. Niarchos 《Astrophysics and Space Science》2005,296(1-4):359-370

A new method for the determination of the proximity effects and gravity darkening exponents in contact binaries of W UMa type is presented. The method is based on Kopal’s method of Fourier analysis of the light changes of eclipsing variables in the Frequency Domain. The method was applied to 36 W UMa systems for which geometric and photometric elements have been derived by the most powerful techniques. The derived values are very close to those predicted by the existing theory of radiative transfer or convective equilibrium.  相似文献   

A 2000-YEAR CONTEXT FOR MODERN CLIMATE CHANGE     

K.A. MAASCH  P.A. MAYEWSKI  E.J. ROHLING  J.C. STAGER  W. KARLEN  L.D. MEEKER  E.A. MEYERSON 《Geografiska Annaler: Series A, Physical Geography》2005,87(1):7-15

ABSTRACT. Although considerable attention has been paid to the record of temperature change over the last few centuries, the range and rate of change of atmospheric circulation and hydrology remain elusive. Here, eight latitudinally well-distributed (pole-equator-pole), highly resolved (annual to decadal) climate proxy records are presented that demonstrate major changes in these variables over the last 2000 years. A comparison between atmospheric ¹⁴C and these changes in climate demonstrates a first-order relationship between a variable Sun and climate. The relationship is seen on a global scale.  相似文献   

The Tennessee-Tombigbee Waterway: An example of synergistic science and engineering     

S. I. Auerbach  P. E. LaMoreaux  G. J. McLindon 《Environmental Geology》1985,7(1-2):3-8

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Can limited ocean mixing buffer rapid climate change?     

KEVIN I. C. OLIVER  REW J. WATSON  DAVID P. STEVENS 《地球，A辑:动力气象学与海洋学》2005,57(4):676-690

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Characterization of zonal winds in the stratosphere of Titan with UVES     

D. Luz  T. Civeit  J.-P. Lebreton  P. Rannou  O. Witasse  F. Ferri 《Icarus》2005,179(2):497-510

Titan has been observed with UVES, the UV-Visual Echelle Spectrograph at the Very Large Telescope, with the aim of characterizing the zonal wind flow. We use a retrieval scheme originally developed for absolute stellar accelerometry [Connes, P., 1985. Astrophys. Space Sci., 110, 211-255] to extract the velocity signal by simultaneously taking into account all the lines present in the spectrum. The method allows to measure the Doppler shift induced at a given point by the zonal wind flow, with high precision. The short-wavelength channel (4200-5200 Å) probes one scale height higher than the long-wavelength one (5200-6200 Å), and we observe statistically significant evidence for stronger winds at higher altitudes. The results show a high dispersion. Globally, we detect prograde zonal winds, with lower limits of 62 and 50 m s⁻¹ at the regions centered at 200 and 170 km altitude, but approximately a quarter of the measurements indicates null or retrograde winds.  相似文献   

Noctilucent cloud formation and the effects of water vapor variability on temperatures in the middle atmosphere     

Christopher P. McKay 《Planetary and Space Science》1985,33(7):761-771

To investigate the occurrence of low temperatures and the formation of noctilucent clouds in the summer mésosphere a one-dimensional time-dependent photochemical-thermal numerical model of the atmosphere between 50 and 120 km has been constructed. The model includes the important chemistry of the hydrogen and oxygen species and transport by eddy and molecular processes. The thermal balance incorporates: heating by solar ultraviolet radiation; transport of chemical potential energy; eddy diffusion and dissipation; molecular conduction; airglow emissions; and infrared cooling by carbon dioxide. A non- LTE parameterization is used to calculate 15 μm band cooling by carbon dioxide. The model self-consistently solves the coupled photochemical and thermal equations as perturbation equations from a reference state assumed to be in equilibrium and is used to consider the effect of variability in water vapor in the lower mesosphere on the temperature in the region of noctilucent cloud formation. It is found that change in water vapor from an equilibrium value of 5 ppm at 50 km to a value of 10 ppm, a variation consistent with observations, can produce a ~ 15 K drop in temperature at 82 km. It is suggested that this process may produce long periods (weeks) of cold temperatures and influence noctilucent cloud formation.  相似文献   

Systematic uncertainties in the analysis of star cluster parameters based on broad-band imaging observations     

R. de Grijs  P. Anders  H. J. G. L. M. Lamers  N. Bastian  U. Fritze-v. Alvensleben  G. Parmentier †  M. E. Sharina  S. Yi 《Monthly notices of the Royal Astronomical Society》2005,359(3):874-894

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