Commuting in the USSR and related research     

Khorev BS  Smolina TK  Vishnevskiy AG 《Soviet geography》1978,19(6):373-378

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The evolution of the crystalline rocks | K. Bailey and R. Macdonald (editors), 1976. Academic Press,London, 484 pp., £ 16.00     

W.G. Ernst 《Earth》1978,14(1):79-80

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Analysis of stellar occultation data: Effects of photon noise and initial conditions     

R.G. French  J.L. Elliot  P.J. Gierasch 《Icarus》1978,33(1):186-202

A new inversion technique for obtaining temperature, pressure, and number density profiles of a planetary atmosphere from an occultation light curve is described. This technique employs an improved boundary condition to begin the numerical inversion and permits the computation of errors in the profiles caused by photon noise in the light curve. We present our assumptions about the atmosphere, optics, and noise and develop the equations for temperature, pressure, and number density and their associated errors. By inverting in equal increments of altitude, Δh, rather than in equal increments of time, Δt, the inversion need not be halted at the first negative point on the light curve as required by previous methods. The importance of the boundary condition is stressed, and a new initial condition is given. Numerical results are presented for the special case of inversion of a noisy isothermal light curve. From these results, simple relations are developed which can be used to predict the noise quality of an occultation. It is found that fractional errors in temperature profiles are comparable to those of pressure and number density profiles. An example of the inversion method is shown. Finally, we discuss the validity of our assumptions. In an appendix we demonstrate that minimum fractional errors in scale height determined from the inversion are comparable to those from an isothermal fit to a noisy isothermal light curve.  相似文献   

The magnetic-binaries problem: Motion of a charged particle in the region of a magnetic-binary system     

A. G. Mavraganis 《Astrophysics and Space Science》1978,54(2):305-313

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Effective temperatures,radii and bolometric magnitudes of Ap and Am stars     

G. S. D. Babu  B. S. Rautela 《Astrophysics and Space Science》1978,58(1):245-254

The effective temperatures radii and bolometric magnitudes of Ap, Am and normal A stars have been estimated from their energy distribution curves between 478 nm and 680 nm. All the Am stars and one Ap star (i.e. CrB) were found to be affected by line blanketing, a rough estimation of which in the respective (B-V) colours has been found out in each case.The range in effective temperature is 0.45–0.60 in terms of (=5040/T _e), while it is 1.8–4.8R in the case of radius, that in bolometric magnitude being from-0^m.67 to+1^m.61. An approximate estimate of the masses shows that they are between 1.5 and 3.0M . All these estimates are in agreement with those of the normal A stars. The Ap and Am stars are found to be slightly evolved and, therefore, are probably in the hydrogen shell-burning phase.  相似文献   

Multiple frequency sounding of a Jovian cloud     

G.S. Orton  R.J. Terrile 《Icarus》1978,35(3):297-307

Prior analysis of 20- and 45-μm flux measurements made from Pioneer 10 of broad regions near the Jovian equator revealed a cold longitudinal inhomogeneity (interpreted as a cloud obscuration) on the rising limb in the South Equatorial Belt. This feature appeared quite prominently at 45 μm and also at 5 μm in ground-based maps made simultaneously with the spacecraft measurements, but it does not appear at visible wavelengths. We describe a method by which the 5-μm observations are used to determine the fraction of 45-μm flux originating from only the region of the SEB obscured by this “anomalous” cloud. This allows the 45-μm data to constrain the cloud properties. On one extreme, the top of the SEB cloud was about 160°K, some 10°K warmer than a cloud in the neighboring South Tropical Zone, if the cloud was optically thick (nontransmissive). On the other hand, if the SEB cloud was as cool as the STrZ cloud, it must have been 60 to 80% transmissive, i.e., somewhat diffuse. With less uncertainty in the fraction of cloud obscuration, the ambiguity between tansmissivity and temperature is significantly diminished. The method described offers a potentially valuable tool for monitoring properties of clouds which do not necessarily appear at visible wavelengths.  相似文献   

The occultation of ϵ Gem by Mars as observed from Agassiz Station     

W. Lilier  C. Papaliolios  R.G. French  J.L. Elliot  C. Church 《Icarus》1978,35(3):395-399

Observations of the April 8, 1976 occultation of ? Gem by Mars made at the Agassiz Station of the Harvard College Observatory have been analyzed to yield temperature profiles of the Martian atmosphere for number densities between 10¹³ and 10¹⁵ cm^?3. Pronounced wavelike structure is evident in both immersion and emersion profiles, with a peak-tto-peak variation of up to 50°K and a vertical scale of 20 km.  相似文献   

Scattering by nonspherical particles and optical properties of Martian dust     

Petr Chýlek  G.W. Grams 《Icarus》1978,36(2):198-203

Ultraviolet spectral reflectance data obtained from the Mariner 9 during the 1971 Mars dust storm were analyzed at two wavelengths to deduce the complex index of refraction of Martian dust. Martian dust particles were considered to be irregularly shaped and randomly oriented nonspherical particles. The analysis shows that the Mariner 9 data are consistent with the scattering by irregular particles with an index of refraction m = 1.59 ? 0.0015i at λ = 0.305 μm and m = 1.55 ? 0.004i at λ = 0.268 μm. Both the real and the imaginary parts of refractive index found are considerably smaller than previously reported results using a spherical shape model for Martian dust particles.  相似文献   

Generation of 1–30 Hz waves near the plasmapause by resonant electron-instability     

K.G. Bhatia  G.S. Lakhina 《Planetary and Space Science》1978,26(3):195-199

A generation mechanism for 1–30 Hz waves of the second category, observed near the plasmapause by Taylor and Lyons (1976), is suggested in terms of a resonant electron instability. The instability arises because of the resonant interaction between the ring current electrons outside the plasmapause and the ordinary mode drift waves. The instability can generate waves in the frequency range from 0.45 to 35.0 Hz in the region between L = 4.5 and 5.5. The instability can also explain satisfactorily the other properties such as no changes in the proton distributions, the direction of the wave magnetic field and the localization of the region of wave activity, associated with these waves.  相似文献   

The development and structure of bright active regions at 2.8 cm     

A. Donati Falchi  M. Felli  P. Pampaloni  G. Tofani 《Solar physics》1978,56(2):335-350

The development of three intense active centers during their appearance on the solar disk is examined using high resolution observations at 2.8 cm. Each region shows a very bright component with brightness temperature > 10⁶ K and size smaller than 20.The development of the bright components have been investigated on different time scales. Intensity fluctuations on a time scale of minutes are within the instrumental accuracy while the evolution over periods of days shows a variation of the flux density up to 30–40% per day.The problem of the bright cores height is discussed. Heights within 10 × 10³ and 40 × 10³ km are found using their apparent displacement on the disk.  相似文献