Secular brightness increases of Titan,Uranus, and Neptune, 1972–1976     

G.W. Lockwood 《Icarus》1977,32(4):413-430

The brightnesses of Titan, Uranus, and Neptune in b (4718 ÅA) and y (5508 ÅA) have increased linearly since 1972 at rates ranging from 0.005 to 0.025 mag yr^?1. The observations were made differentially on a number of nights each season with respect to a network of comparison stars whose relative magnitudes were determined by independent measurements. Solar phase coefficients were derived for each object, and all observations have been normalized to zero solar phase angle and mean heliocentric distances. No explanation for the changes has been found, but a possible influence of solar activity upon planetary albedo is suggested by the fact that all of the objects observed have brightened during the declining half of the solar cycle.  相似文献   

Frequency domain light curve analysis of partially eclipsing binary systems: With an application to β Persei (Algol)     

O. Demircan 《Astrophysics and Space Science》1977,47(2):459-488

Kopal's new iterative method for analysing partially eclipsing binary light curves in the frequency domain has been put into a form suitable for applications, and explicit forms for basic expressions developed. To facilitate the computations in practice, the required newS _m -functions, which are expressed in terms ofJ _, ⁰ -integrals, have been extensively tabulated by making use of hypergeometric series. The automated method has been tested successfully on the light curves of Persei (Algol). Short information on the system and the revised sets of elements including a new determination of the limb-darkening coefficient in the ultraviolet have been presented.  相似文献   

Coherent amplification and pulsar phenomena     

Lee W. Casperson 《Astrophysics and Space Science》1977,48(2):389-399

A modification of the rotating-star model has been developed to interpret the periodic energy bursts from pulsars. This new configuration involves -directed oscilltion modes in the stellar atmosphere or magnetosphere, and most aspects of the typical pulse characteristics are well accounted for. Gain is provided by resonant interactions with particles trapped in the stellar magnetic field. The most significant feature is the fact that highly directional beaming of the output energy results as a natural consequence of coherence between the radiation fields emerging from various locations about the pulsar; and a localized radiation origin is not required.  相似文献   

Energetic properties of interplanetary plasma at the earth's orbit following the August 4, 1972 flare     

C. D'uston  J. M. Bosqued  F. Cambou  V. V. Temny  G. N. Zastenker  O. L. Vaisberg  E. G. Eroshenko 《Solar physics》1977,51(1):217-229

Solar wind and interplanetary magnetic field data were obtained by the PROGNOZ 1 and PROGNOZ 2 satellites during the period following the August 4, 1972 (0621 UT) solar flare. A thermalized plasma was recorded one hour after the shock followed two hours later by the plasma piston with a bulk velocity higher than 1700 km s^-1. The comparison between the PROGNOZ and PIONEER 9 solar wind data shows an attenuation of the plasma properties with the deflection from the flare's meridian.  相似文献   

Solar particle propagation from 1 to 5 AU     

R. D. Zwickl  W. R. Webber 《Solar physics》1977,54(2):457-504

A statistical analysis of solar particle events, observed by the GSFC-UNH charged particle detector on board Pioneer 10 and Pioneer 11 from March 1972 to December 1974 (from 1 to 5 AU for each spacecraft), is carried out with the goal of experimentally determining the statistical average interplanetary propagation conditions from 3 to 30 MeV. A numerical propagation model is developed that includes diffusion with a diffusion coefficient of the form k _r =k _o r , convection, adiabatic deceleration, and a variable coronal injection profile. The statistical analysis is carried out by individually analyzing each of five parameters (t _max, (t_max), t ₅, ) that are uniquely defined in a solar particle event. Each of the five parameter data sets were analyzed in terms of both a spacecraft-solar flare connection longitude 50°, and a numerical model that employed a variable exponential decaying coronal injection profile.The five individual parameter analyses are combined with the results that the statistical average radial interplanetary diffusion coefficient from 1 to 5 AU is given by k _r = (1.2 ± 0.4) × 10²¹ cm² s^-1 with = 0.0± 0.3 for 3.4 to 5.2 MeV protons and k _r = (2.6 ± 0.6) × 10²¹ cm² s^-1 with () = 0.0± 0.3 for 24 to 30 MeV protons. Using the classical relationship for the radial scattering mean free path _r, i.e. k _r = _r/3, we obtain _r = 0.09 ± 0.03 AU and 0.075 ± 0.020 AU for the low and high energy data, respectively. These results show, from 1 to 5 AU and from 3 to 30 MeV, that _r is both independent of radial distance and approximately independent of rigidity (for _r~P , where P = rigidity, = -0.15 ± 0.20).The above diffusion coefficients are inconsistent With both the predictions of the diffusion coefficient from present theoretical transport models and with the diffusion coefficient used in modulation studies at low energies.  相似文献   

Plasmasphere response to the onset of quiet magnetic conditions: Plasma convection patterns     

E. Rabe  M.W.J. Scourfield 《Planetary and Space Science》1977,25(3):303-308

A whistler study has been made of plasma convection within the plasmasphere during a transition from steady moderate geomagnetic activity to quiet conditions. Continuous whistler data recorded at Sanae, Antarctica (L= 3.98) for the period 0400 UT, 10 July to 0400 UT, 11 July 1973 have been analyzed in 15 min intervals.This study has revealed two distinct bulges in the plasmasphere centred on 1700 and 0100 UT. The bulges appear to result from the outward flow of plasma rather than the addition of new plasma. We tentatively interpret the late bulge at 0100 UT as being the duskside bulge of earlier studies rotated into the midnight region. In this bulge, plasma above L = 3.8 appears to convect outwards to form the bulge whereas plasma at lower L-values is relatively undisturbed. For the early bulge (1700 UT) the plasma convection pattern is similar over all observable L-values and closely reflects the shape of the estimated plasmapause in that region. Comparison of the bulges, with those obtained by Carpenter (1966) suggests that the onset of quiet conditions results in a general displacement of the bulges in an eastward direction by about 3 hr.  相似文献   

The equations of motion of an artificial satellite in nonsingular variables     

G. E. O. Giacaglia 《Celestial Mechanics and Dynamical Astronomy》1977,15(2):191-215

The equations of motion of an artificial satellite are given in nonsingular variables. Any term in the geopotential is considered as well as luni-solar perturbations up to an arbitrary power ofr/r, r being the geocentric distance of the disturbing body. Resonances with tesseral harmonics and with the Moon or Sun are also considered. By neglecting the shadow effect, the disturbing function for solar radiation is also developed in nonsingular variables for the long periodic perturbations. Formulas are developed for implementation of the theory in actual computations.  相似文献   

Magnetic properties of x-ray bright points     

L. Golub  A. S. Krieger  J. W. Harvey  G. S. Vaiana 《Solar physics》1977,53(1):111-121

Using high resolution KPNO magnetograms and sequences of simultaneous S-054 soft X-ray solar images we have compared the properties of X-ray bright points (XBP) and ephemeral active regions (ER). All XBP appear on the magnetograms as bipolar features, except for very newly emerged or old and decayed XBP. We find that the separation of the magnetic bipoles increases with the age of the XBP, with an average emergence growth rate of 2.2 ± 0.4 km s^–1. The total magnetic flux in a typical XBP living about 8 hr is found to be 2 x 10¹⁹ Mx. A proportionality is found between XBP lifetime and total magnetic flux, equivalent to 10²⁰ Mx per day of lifetime.Operated by the Association of Universities for Research in Astronomy, Inc. under contract with the National Science Foundation.  相似文献   

On the nature of polar cap magnetic activity during undisturbed periods     

B.M. Kuznetsov  O.A. Troshichev 《Planetary and Space Science》1977,25(1):15-21

The correlation between the polar cap geomagnetic variations (H-traces) and the changes of the azimuthal (Y_SE) and vertical (Z_SE) components of the interplanetary magnetic field (IMF) during undisturbed periods is examined. It is shown that peak-to-peak correlation between Y_SE and geomagnetic horizontal component variations may be generally observed in the daytime cusp region, independently of the magnitude and polarity of the Z_SE. The existence of the DP₃ disturbances associated with the northward component Z_SE > 0 is confirmed. It is shown that the disturbances due to the vertical component of the IMF dominate in the region near the pole. In so far as the southward component of the IMF generates both polar cap disturbances and geomagnetic substorms, the disturbances in the region near the pole, associated with Z_SE < 0, may be regarded as a precursor of a substorm. On this basis a new index of the polar cap magnetic activity PC_L, characterizing the changeability of the magnetic field is proposed. It is shown that the increase of the PC_L index is followed in 1–2 hr by a substorm in 70% of events considered.  相似文献   

Auroral ion velocity distributions for a polarization collision model   总被引：1，自引：0，他引：1  

J.-P. St-Maurice  R.W. Schunk 《Planetary and Space Science》1977,25(3):243-260

We have calculated the effect that convection electric fields have on the velocity distribution of auroral ions at the altitudes where the plasma is weakly-ionized and where the various ion-neutral collision frequencies are much smaller than the ion cyclotron frequencies, i.e. between about 130 and 300 km. The appropriate Boltzmann equation has been solved by expanding the ion velocity distribution function in a generalized orthogonal polynomial series about a bi-Maxwellian weight factor. We have retained enough terms in the series expansion to enable us to obtain reliable quantitative results for electric field strengths as large as 90 mV m^?1. Although we have considered a range of ion-neutral scattering mechanisms, our main emphasis has been devoted to the long-range polarization interaction. In general, we have found that to lowest order the ion velocity distribution is better represented by a two-temperature or bi-Maxwellian distribution than by a one-temperature Maxwellian, with there being different ion temperatures parallel and perpendicular to the geomagnetic field. However, the departures from this zeroth-order bi-Maxwellian distribution become significant when the ion drift velocity approaches (or exceeds) the neutral thermal speed.  相似文献