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A magnetic dipole rotating around an axis perpendicular to the rotation axis of the sun can account for the characteristics of the surface large-scale solar magnetic fields through the solar cycle. The polarity patterns of the interplanetary magnetic field, predictable from this model, agree with the observed interplanetary magnetic sector structure.
A large-scale structure observed in the photospheric magnetic field is carried out into the heliosphere by the solar wind. At Earth the resulting interplanetary magnetic field has polarity away from the Sun for several consecutive days followed by an abrupt reversal and several days with field polarity toward the Sun. Low-pressure troughs near the Gulf of Alaska appear to have significantly larger area when the interplanetary field is away from the Sun than when it is toward the Sun. This relation persisted during most of the winters of 1951 to 1973. Surface pressures around the Gulf of Alaska during some winters were in anti-phase for interplanetary field toward and away from the Sun. During the two days after a polarity reversal, the accuracy of the best weather forecasts for the continental United States appears to be significantly lower than at other times. Polarity reversals that are accompanied by energetic interplanetary conditions appear to be associated with a larger decrease in the area of the low pressure troughs.
It is shown that the use of a two-parameter limbshift and a meridional flow velocity fits solar velocity data better than the standard analysis defined by Howard et al. (1980). The data used are the coarse residual velocity arrays, with 34 equal intervals in both sine latitude and sine longitude. There are a total of 2899 full-disk observations between January 1, 1967, and December 12, 1980. The original velocity fields are reconstructed by adding into the residual arrays the large-scale patterns that were measured and removed on a daily basis by a standard reduction. Tests of this reconstituded data set show that no significant errors are introduced in the analysis of large-scale velocity fields. The results of the analysis presented here imply that the study of solar velocity pattern at the level of a few m/s requires that magnetic regions be treated separately from nonmagnetic regions.
A least squares power spectrum analysis of daily sunspot numbers for the last 122 years yielded a statistically significant peak at 12.0715 plus or minus .002 days period. This feature at 11.685 days (sidereal) of the sunspot spectrum is discussed in relation to the peak at 12.22 days (sidereal) which Dicke found in his oblateness data. The data is attributed to the Sun's core if the core rotates at either 12.0715 days or 24.1430 days period (synodic). It is suggested that spacecraft observations combined with correlative analysis of solar surface features between eastern and western hemispheres could further reveal a basic core periodicity. A Dicke type space oblateness experiment is discussed for providing better photospheric observations than a ground instrument to determine the core periodicity.
The procedure for reducing the data acquired during the Mt. Wilson Observatory synoptic program is described, and a program for acquiring as many scans per day as possible of the solar magnetic and velocity fields is discussed. A fitting formula which removes the background velocity field from each scan has been derived. It is suggested that the difference between the limb shift along the north-south axis and the east-west axis may be due to the meridional circulation.
It is known that there are variations in the atmospheric processes with a period close to that of the rotation of the Sun (27 days). The variations are discovered in tropospheric processes, rainfalls, geopotential and in stratosphere. The main theoretical problem is the identification of the physical process by which these heterogeneous solar and meteorological phenomena are connected. Ivanovsky and Krivolutsky proposed that the periodic heating of the ozone layer by the short wave radiation would be the reason of excitation the 27-day oscillations. It was also assumed that excitement takes place in condition of resonance with an excited mode corresponding to the conditions present in the stratospheric circulations. The possibility is discussed of the resonant excitation and presentation is made of the data analysis results which support this idea.
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Magnetic field data obtained on Pioneer 6 flights are presented in graph form as hourly averages. The spacecraft and magnetic field detector are described. The standard data analysis procedures are also given.
The angular momentum of stars and its distribution within the stars are discussed. Observed surface velocities dependent on a variety of factors are examined, including age, mass, spectral type, and binarism. The rotation and surface velocity of the sun are also considered.
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Daily spectroscopic observation of the rotation of the sun indicates that several slow changes have taken place since 1967. The equatorial rotation rate of the photospheric gas has gradually increased until, in 1976, it is close to the sunspot rate determined by Newton and Nunn (1951). The latitude gradient at middle latitudes decreased starting in 1974, and the latitude gradient at high latitudes has increased in the same interval. An increase in the number of low-latitude active regions may be responsible for accelerating the photospheric gas.
A least-squares power-spectrum analysis of 122 years of Zurich daily sunspot numbers yields a statistically significant peak at a 12.0715 + or - 0.002 day period. This feature of the sunspot spectrum may be associated with the peak at 12.22 days (sidereal) which Dicke (1976) found in his oblateness data, and may be attributable to the sun's core if it rotates at either a 12.0715-day or a 24.1430-day period (synodic).
We examine the background velocity fields of the sun as observed at Mount Wilson. The method of velocity reduction of the full-disk Mount Wilson data is outlined. We describe a number of tests that have been carried out in order to find an instrumental origin for short-term rotation variations and a large-scale background line-shift - the ears. No instrumental cause can be found for this ear effect, although such a cause cannot yet be ruled out.
New measurements of frequencies of various modes of acoustic waves trapped within the sun are reported for degrees up to 98 which allow the convective envelope to be isolated. For degrees between 20 anad 98, no evidence is found that internal rotation differs significantly with depth or latitude from the rotation of surface magnetic field patterns. Modes covering a wide latitude range have systematically lower frequencies than those confined near the equator, indicating the existence of a structural asymmetry within the sun.
Reexamination of the published sunspot rotation rates from Mount Wilson for the period from 1921 to 1982 suggests that the sun rotates more rapidly when there are fewer sunspots. This behavior is seen over the course of each cycle with the most rapid rotation usually observed at sunspot minimum. It is also seen in hemispheric differences with the southern hemisphere, having fewer spots, rotating more rapidly than the northern hemisphere. Furthermore, the rotation rate averaged over each cycle also shows that the sun rotates more rapidly during cycles with fewer sunspots and less sunspots area. This inverse correlation between sunspot area and rotation rate suggests that during the Maunder minimum the sun may have rotated slightly faster than is observed today.
We use 'stackplot' displays to compare observations of the photospheric magnetic field during sunspot cycle 21 with simulations based on the flux-transport model. Adopting nominal rates of diffusion, differential rotation, and meridional flow, we obtain slanted patterns similar to those of the observed field, even when the sources of flux are assigned random longitudes in the model. At low latitudes, the slopes of the nearly vertical patterns of simulated field are sensitive to the rotation rate used in the calculation, and insensitive to the rates of diffusion and flow during much of the sunspot cycle. Good agreement between the observed and simulated patterns requires a synodic equatorial rotation period of 26.75 +/- 0.05 days.
Proposed telescope based on absorbing Fourier-transform grids images full Sun at unprecedented resolution. Overcomes limitations of both conventional optical and pinhole cameras. Arrays of grids and detectors configured for sensitivity to selected fourier components of x-ray images.
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