Dynamical interpretation of observed plasmasphere deformations

Based on all of the OGO-5 light ion density measurements (covering the period from March, 1968 to May, 1969), a definition of “isolated plasma regions” was employed to locate the most prominent patches of enhanced light ion densities in the midst of the depleted region, outside of the main plasmasphere. On the dayside, the distribution of these isolated plasma in L.T. vs. L coordinates was quite similar to that of the “detached plasma regions” by Chappell (1974a). On the nightside, however, the new distribution revealed more frequent occurrence of these regions. Elongated thick plasmatails produced during periods of sudden enhancement of convection electric fields and subsequentially thinning and corotating of the plasmatails during quieting periods, in general, could account for the statistical distribution as well as the individual events, such as those between March 27 and April 2, 1968 and Oct. 21 and Oct. 24, 1968. As demonstrated by Kivelson (1976), wave-particle interactions could produce tremendously complicated structures observed in the near vicinity of the plasmapause and far away from the plasmasphere. Examination of H⁺ and He⁺ density measurements for period of Aug. 12–Aug. 20, 1968 indicated that the density reduction of the plasmasphere during a magnetic storm was on the same order of magnitude as that obtained from whistler techniques during a magnetospheric substorm.     

Identification of two solar X-ray sources at the 22 September 1968 total eclipse

Study of nearly 200 records of radio signal strength indicates that a major portion of the ambient D layer absorption on 22 September 1968 can be attributed to two strong X-ray sources. The hottest source was located on the eastern limb and showed evidence of cooling fromT _wien=(3.6±0.3)×10⁶K toT _wien=(2.7±0.2)×10⁶K over a 2 1/2 h period. The other source was located near the western limb and showed no appreciable temperature change during the eclipse period. Except for the apparent source decay, the sources are similar to those found at previous eclipses using similar techniques (Meisel; 1968, 1969).     

Evolution du spectre de la Nova Delphini 1967 dans le proche infrarouge en 1969

Spectra of Nova Del 1967 have been obtained in the photographic infrared during the period March to November 1969. The gradient in the region 1.3–1.7 µ^–1 has decreased from 3.06 in November 1968 to 2.57 in November 1969. The main spectral features occurring in the wavelength range 5800–9600 Å are described, while the profiles of some strong lines are displayed on Figures 2–6.

---

---

Les observations ont été effectuées à l'Observatoire de Haute-Provence (CNRS).     

Analysis of the orbital inclination of 1963-27A

The Agena B upper-stage rocket 1963-27A was launched into near-circular orbit, inclined at 82.3° to the Equator, on 29 June 1963. Its orbital elements were available at 52 epochs over the 16 month interval prior to its decay on 26 October 1969. During this period the satellite passed through 31:2 resonance and the variation in orbital inclination near this event was analysed to obtain two lumped geopotential harmonics of order 31. Since the resonance was a weak feature in the data, the resulting values are poorly defined.Either side of the resonance period, the inclination was used to estimate the mean atmospheric rotation rate Λ rev day^?1. The values obtained were Λ = 0.85 ± 0.18 at a height of 440 km for the period June 1968 to February 1969 and Λ = 1.13 ± 0.10 at 338 km for the period June to October 1969.     

The connection between the pulsational and orbital periods for eclipsing binary systems

Considering a sample of 20 eclipsing binary systems with δ Scuti type primaries, we discovered that there is a possible relation among the pulsation periods of the primaries and the orbital periods of the systems. According to this empirical relation, the longer the orbital period of a binary, the longer the pulsation period of its pulsating primary. Among the sample, the masses of the secondaries and the separations between the components are known for eight systems for which a  log  P _puls  versus log  F (the gravitational pull exerted per gram of the matter on the surface of the primaries by the secondaries) diagram also verifies such an interrelation between the periods. So, as the gravitational force applied by the secondary component onto the pulsating primary increases, its pulsation period decreases. The detailed physics underlying this empirical relation between the periods needs further confirmation, especially theoretically. However, one must also consider the fact that the present sample does not contain a sufficiently large sample of longer period  ( P > 5 d)  binaries.     

Determination of the pressure coefficients for neutron monitor and multiplicity analyzer measurements

To determine the air pressure dependence of the total rates of the neutron monitor NM-64 and of the observed multiplicities 1, 2, 4 and 6 of the neutron multiplicity analyzer the one-station method with iterative least squares described by Martinelle (1968) is used. This method is extended with a criterion for optimizing the length of the filter taken from Jenkins and Watts (1969). To show the effect of this method also classical regression estimates are given. Pressure coefficients are obtained for overlapping periods of three months for the greater part of the years 1970–1974.     

The relationship between solar activity and the H and K line cores in integrated sunlight

In this paper we present and analyze new data on the cores of the H and K lines of ionized calcium in the spectrum of integrated sunlight. The intensities of the components H _2v , H₃, H _2r , K _2v , K₃, and K _2r in the line cores were measured in terms of the continuum intensity at 4000 Å during a solar rotation in September 1969. Other data on these components, obtained at or close to the times of solar minimum (September 1964) and solar maximum (September 1968), were also included. The intensities of these features are compared with two indices of solar activity: the Ca ii plage index and the 2800 MHZ signal. The average correlation coefficients between the intensities of the measured features and those indices were 0.69 and 0.64, respectively. Our results are consistent with those of Bumba and Riková-Topolová (1967) for a solar rotation period in 1965.The method and results should provide a detailed quantitative basis for the study of the activity cycles and rotation periods of solar-type stars.First Weather Wing, Hickman Air Force Base, HI 96824, U.S.A.     

The effect of gradient and curvature drifts on Forbush decreases

The average profile of Forbush decreases, produced by eastern-, central- and western-region solar flares is obtained separately by superposed epoch analysis for the periods 1966–1969 (qA < 0) and 1971–1979 (qA > 0). It is observed that the recovery of an average Forbush decrease from the maximum depression level is faster for the situation qA > 0 than for the situation qA < 0. This is in accordance with expectations from the drift theory. It is also observed that the drift effect is more pronounced for western-flare Forbush decreases which, of course, have a smaller magnitude compared to eastern- and central-flare Forbush decreases.The average profiles of simple and complex type Forbush decreases are also obtained separately for three periods 1965–1979, 1971–1979, and 1981–1987. It is found that the average profiles of simple and complex type Forbush decreases observed during the period 1965–1969 and 1971– 1979 are quite in agreement with drift theory. The anomalous behavior of average Forbush-decrease profiles during the period 1981–1987, especially in simple type Forbush decreases, is also explained by a drift current sheet tilt model.     

The orbit of proton 4 redetermined,with geophysical implications

The orbit of Proton 4, 1968-103A, has been redetermined, in greater detail and with better accuracy, in order to clarify previously puzzling features in the variation of orbital inclination. Orbital parameters have been determined at 25 epochs between December 1968 and July 1969, using about 1600 optical and radar observations with the RAE orbit refinement program PROP 6.During January 1969 the orbit passed through 31:2 resonance—when the ground track over the Earth repeats every two days after 31 revolutions of the satellite. A simultaneous least-squares fitting of theoretical curves to the values of inclination and eccentricity between 14 December 1968 and 6 March 1969 has yielded values for two pairs of lumped 31st-order geopotential coefficients, appropriate to an inclination of 51.5°. This is the first specific evaluation of 31st-order coefficients.The 15 values of inclination after the resonance, from March to near decay in July 1969, have been used to determine mean, morning and afternoon-evening values for the rotation rate of the atmosphere at a height near 260 km; the values of rotation rate, namely 1.1, 0.9 and 1.3 rev/day respectively, confirm the trends already established from analysis of other satellite orbits.     

The variation of the light curve of W Ursae Majoris

A new set of photoelectric B and V observations of W Ursae Majoris obtained during a period of one week in 1968 is presented.From the measurements it can be concluded that in general the light curve in both colors is free from complications. In particular, no systematic brightness differences between consecutive periods can be found.The observations made during total eclipse in two different periods yield flat minima fitting almost perfectly together, the mean error of the single measurement beeing of the order of 0.^m003. The duration of the phase of totality is estimated to 0.036P=17.3 m thus confirming the value given by Cester and Gridelli.From a plot of the square deviations of the single observations (I/I)² from the mean intensity curve vs phase it can be shown that the scattering decreases strongly during primary eclipse thus indicating that the source producing these fluctuations is essentially confined to the space between the two components. A comparison with earlier photoelectric observations also supports the assumption that the variational behavior of the light curve is caused by a gaseous cloud between the two components rather than by an envelope surrounding the whole system.Operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation.     

Rotation of the Solar Equator

Regular measurements of the general magnetic field of the Sun, performed over about half a century at the Crimean Astrophysical Observatory, the J. Wilcox Solar Observatory, and five other observatories, are considered in detail for the time 1968?–?2016. They include more than twenty-six thousand daily values of the mean line-of-sight field strength of the visible solar hemisphere. On the basis of these values, the equatorial rotation period of the Sun is found to be 26.926(9) d (synodic). It is shown that its half-value coincides within error limits with both the main period of the magnetic four-sector structure, 13.4577(25) d, and the best-commensurate period of the slow motions of the major solar system bodies, 13.479(22) d (sidereal). The probability that the two periods coincide by chance is estimated to be about \(10^{-7}\). The true origin of this odd resonance is unknown.     

On the continuum intensity of the umbra of large sunspots

Spectral observations of large sunspots during the period June 1968 – Dec. 1969 in five wavelength regions between 4795 and 6775 are discussed. Selecting the best observations of two very large sunspots, we find slightly lower umbral intensities than derived by earlier observers. It is suggested that the small difference may be explained by the fact that earlier observers have used an average value, whereas we believe that the minimum value gives a more correct estimate of the umbral intensity.     

Coronal magnetic structure at a solar sector boundary

The persistent large-scale coronal magnetic structure associated with a sector boundary appears to consist of a magnetic arcade loop structure extending from one solar polar region to the other in approximately the north-south direction. This structure was inferred from computed coronal magnetic field maps for days on which a stable magnetic sector boundary was near central meridian, based on an interplanetary sector boundary observed to recur during much of 1968 and 1969.     

Iowa catalog of solar X-ray flux (2–12 Å)

The absolute X-ray flux from the whole disc of the sun in the wave length range 2 to 12 Å has been observed for a prolonged period by University of Iowa equipment on the earth-orbiting satellite Explorer 33 and the moon-orbiting satellite Explorer 35, both of the Goddard Space Flight Center of the National Aeronautics and Space Administration. The observations are continuing at the date of writing (July 1969). A comprehensive catalog of the flux F (2–12 Å) is being produced. The observational technique and the scheme of reducing data are described herein. Sample tabulations and plots are given. A catalog of tabular and graphical data with a time resolution of either 81.8 or 163.6 sec has been completed for the following periods: From Explorer 33: 2 July 1966 to 27 July 1967 From Explorer 35: 26 July 1967 to 18 September 1968 These blocks of data have been delivered to the National Space Science Data Center National Aeronautics and Space Administration Goddard Space Flight Center Greenbelt, Maryland 20771, U.S.A. and made available through that agency to interested workers in solar and ionospheric physics. Further blocks of data will be made available as they are completed. An abridged summary of principal flares is published in the monthly Solar-Geophysical Data of the U.S. Department of Commerce, Environmental Science Services Administration.     

Observations of Jupiter at 13-cm wavelength during 1969 and 1971

Radio observations of Jupiter have been carried out at Goldstone, CA at a wavelength of 13 cm during the oppositions of 1969 and 1971. In 1969, circular-polarization and total-flux measurements were made with a 64-m radio telescope. From May through October 1971, Jupiter's flux density was measured at weekly intervals with a 26-m antenna. Analysis of the 2 years of data has yielded the following results: (a) The upper limit to the degree of circular polarization over the longitude ranges 10–100° and 160–250° System III (1957.0) is 1%; (b) the flux data have been used to derive a magnetospheric rotation period which is approximately 0.37^s longer than the IAU System III (1957.0); (c) the flux-density data define beaming curves which are apparently different from 11-cm beaming curves measured in 1964; (d) Jupiter's peak flux density decreased by ～20% between 1964 and 1971, and 8% between 1969 and 1971.     

An investigation of some large directional discontinuities in the solar wind plasma using multisatellite observations

Eleven large directional discontinuities in the solar wind, simultaneously observed by Explorers 33, 35 and Heos 1 in the period Dec. 1968 to Jan. 1969, have been studied by the triangulation method. Testing the discontinuity normals deduced from the wind speed and timing parameters against those given by the magnetometer observations on different models suggests that 8 were tangential, 2 were rotational while 1 could not be identified. 3 small tangential discontinuities arriving within a period 35 min were also studied and as a result it is suggested that the solar wind remained stratified in separation planes over a distance 0.01 AU during that time. The implication of these results is briefly discussed.     

Determination of zonal wind speeds at heights near 530 km from the orbit of Explorer 24 (1964-76A)

The orbit of Explorer 24 (1964–1976A) has been determined at 18 epochs during the five month period prior to its decay in October 1968, using the RAE orbit refinement computer program PROP6. As a balloon, the satellite was strongly influenced by atmospheric perturbations, despite its high perigee altitude near 490 km. It therefore provided an opportunity of determining atmospheric rotation rates at high altitude. The rotation rate, Λ rev day^?1, was estimated from the observed variation in orbital inclination, after the removal of perturbations including those due to solar radiation pressure.The mean rotation rates, averaged over local time, are Λ = 0.98 for 18 May to 18 August 1968 at 542 km; Λ = 1.06 for 18 May to 13 October 1968 at 533 km.For morning conditions, Λ = 0.9 for 22 June to 20 July 1968 at 540 km; Λ = 0.8 during September 1968 at 513 km.For evening conditions, Λ = 1.1 for 18 May to 15 June 1968, and for 26 July to 7 September 1968, at 540 km and 536 km respectively; Λ = 1.3 for 28 September to 13 October 1968 at 484 km.Further, the maximum W to E zonal wind has been estimated to occur at 20.5 h local time, during the period of the analysis.     

Unified theory of the interplanetary magnetic field

A simple model is used to present a unified picture of the polarity pattern of the interplanetary magnetic field observed during the solar cycle. Emphasis in this paper is on the field near solar maximum. The heliographic latitude dependence of the dominant polarity of the interplanetary magnetic field is explained in terms of weak poloidal (dipolar) field sources in the sun's photosphere. Unlike the Babcock theory, the author hypothesizes that the dipolar field exists at equatorial latitudes (0–20°), too, (as well as in polar regions) and that the major source of the interplanetary magnetic field observed near the ecliptic plane is the dipolar field from equatorial latitudes. The polarity of the interplanetary field data taken in 1968 and in the first half of 1969 near solar maximum may possibly be explained in terms of a depression of the dipolar field boundary in space. The effect on the solar wind of the greater activity in the northern hemisphere of the sun that existed in 1968 and in the first half of 1969 is believed responsible for this hypothesized depression, especially near solar maximum, of the plane separating the + and - dipolar polarity below the solar equatorial plane in space. Predictions are made concerning the interplanetary field to be observed near the ecliptic plane in each portion of the next solar cycle.     

Type II radio bursts and particle acceleration

328 particle events recorded during 30 months from January 1, 1966 to June 30, 1968 (taken from the new Catalog of Solar Particle Events, 1955–1969) are compared with the occurrence of 166 type II radio bursts during the same period. The results of this comparison give a convincing evidence that proton acceleration to higher energies in flares (the second acceleration step) is closely connected with the type II burst occurrence. The shock wave appears to originate near the time when the impulsive burst occurs, and the second acceleration step follows immediately the first one; in some cases the second step sets in while the first step is still in progress.A detailed analysis indicates that we may need even three different acceleration mechanisms in flares: The first one gives rise to electrons which produce the microwave and hard X-ray bursts (and it probably also accelerates protons to low energies); the second, which sometimes coincides (but mostly does not coincide) with the first one, produces beams of electrons which give rise to type III bursts; and the third one, characterized by the type II burst-producing shock wave, accelerates (on some, rather rare occasions) the particles, preaccelerated by the first mechanism, to higher energies.Mitteilungen aus dem Fraunhofer Institut Nr. 125.Grant of Stifterverband für die Deutsche Wissenschaft.     

Solar activity cycles,north/south asymmetries,and differential rotation associated with solar spin-orbit variations

The possible role of the Sun's planetary-induced spin-orbit dynamics in the generation of various solar oscillations is examined using simple approaches and heuristic models. Theoretically, the 22.5-yr dipole inversion magnetic cycle and the recently described 17-yr neutral line topology cycle can be derived from the non-linear mixing of two oscillations with periods of approximately 20 and 165 years. Oscillations with such periods are observed in two aspects of the Sun's spin-orbit dynamics. The 20-yr oscillation is the fundamental variation in the angular momentum of the solar body with respect to the solar system center-of-mass, while the 165-yr oscillation is the lowest-frequency component of the spin projection variations. It is shown that these two oscillations when mixed non-linearly yield, to a 1st-order approximation, the correct phase and frequency of the observed 17.5- and 22.5-yr magnetic cycles. By allowing an asymmetric shape to the 165-yr oscillation, the frequency modulation inherent in the Hale cycle (and sunspot cycle) is reproduced, yielding a more accurate estimate of solar activity. The asymmetric 165-yr oscillation matches the combination of the two lowest frequency components (165- and 84-yr periods) of the spin projection variations. Hemispheric sunspot asymmetry cycles, north/south differences in convective zone rotational velocities, and meridional flows are also shown to be expected byproducts of classical spin-orbit effects. Finally, the problem of low activity epochs (e.g., Maunder minimum) can be seen as a natural outcome of the interactions among the driving and driven oscillations involved in the conservation of solar system angular momentum.