摘要:

Comparisons have been made of the cosmic ray intensities measured by the Pioneer 8 detector and by ground‐based neutron monitors located at different vertical cutoff rigidities for three Forbush decreases in 1968 and for the 11‐year solar modulation. It is observed that the rigidity dependence of the three large Forbush decreases was substantially different than the corresponding 11‐year variation at rigidities from

ISSN:0148-0227    

DOI:10.1029/JA075i034p06885

年代:1970

数据来源: WILEY

摘要:

The effect of charge exchange and photoionization of neutral hydrogen penetrating the supersonic solar wind region from the interstellar medium is taken into account by constructing appropriate source terms for the equations of the flow. The equations are solved numerically for densities of 1, 5, and 10 cm−3in the interstellar medium. It is shown that the size of the supersonic solar wind region varies with these densities from 50 to 8 AU in the apex direction if the momentum of the incoming neutral hydrogen is neglected. If the momentum of the incoming neutral hydrogen is taken into account, it is found to be sufficient to halt the flow of the solar wind at about 45 AU for an interstellar neutral hydrogen density of 1 cm

ISSN:0148-0227    

DOI:10.1029/JA075i034p06892

年代:1970

数据来源: WILEY

摘要:

The steady‐state diffusive motion of ionized atoms (more massive than hydrogen) in the solar corona has been investigated theoretically, with special emphasis on relating the flow velocity and density of these ions to the flow properties of the ionized hydrogen background. The basic approach taken in this study was to regard the ions as ‘test particles’ interacting with the background electrons and protons; an explicit form of the momentum equation for the ions was derived that contained, as parameters, the density, the velocity, and the temperature of the electrons and protons. These parameters were assumed to be unperturbed by the addition of the ions and were obtained from two models of a simpler corona that consists of ionized hydrogen only: the model of E. N. Parker and the model of P. A. Sturrock and R. E. Hartle. The momentum equation was combined with the equation for conservation of mass and was solved to obtain, as a function of distance from the sun, the flow velocity and density for certain representative species of ions. It was found that the ions diffuse away from the sun with velocities somewhat lower than the velocity of the background, and that their relative abundance increases gradually and slowly with h

ISSN:0148-0227    

DOI:10.1029/JA075i034p06899

年代:1970

数据来源: WILEY

摘要:

The two‐fluid solar wind model predicts values for wind speed and proton temperature that are lower than average observed values; however, the predictions are consistent with the empirical relation of Burlaga and Ogilvie, in which the square root of the proton temperature is proportional to the wind speed. Since observed values of wind speed and proton temperature are typically higher than those of the two‐fluid model, it is concluded that energy must be supplied by dissipation of nonthermal energy from an external source. The two‐fluid model is therefore extended by including ad hoc an energy source in the proton heat equation whose strength and spatial distribution is varied to determine the general requirements of such a source. The main features of our results are: Heat deposited inside the heliocentric radiusr≃4Rsresults in a significant increase in wind speed with negligible increase in proton temperature. Depositing heat over the ranger≳25Rsresults in a large increase in proton temperature and negligible increase in wind speed. By depositing heat over the extended range 2Rs≲r≲25Rs, solar wind speeds and proton temperatures can be brought into direct correspondence with the empirical results of Burlaga and Ogilvie. On the basis of this model, we conclude that primary energy deposition should take place

ISSN:0148-0227    

DOI:10.1029/JA075i034p06915

年代:1970

数据来源: WILEY

摘要:

Data from a cosmic dust experiment on Pioneer 8 have revealed the speed and radiant of six cosmic dust particles in 390 days of measurement. This gives a particle flux of 2×10−4/meter²/sec/2π ster. The probability of an extraneous velocity measurement during the 265 days is 2.6×10−7. Each of the six events has been analyzed for orbital elements, including true velocity, inclination, perihelion distance, and aphelion distance. Particle mass and energy have been derived on the basis of laboratory calibrations of the sensors using a two‐million‐volt electrostatic dust particle accelerator. The particle velocities range from 8.2 to 31.2 km/sec. The particle energies range from 6 to more than 80 ergs. Only one of the six particles exhibited retrograde orbital

ISSN:0148-0227    

DOI:10.1029/JA075i034p06932

年代:1970

数据来源: WILEY

摘要:

A study of 19‐GHz (1.58‐cm) solar radio bursts recorded at the Slough Solar Radio Observatory from July 1967 to June 1969 suggests that they can be used as reliable indicators of proton events and of PCA's, provided that (a) the peak flux increase during the burst is>50% of the pre‐burst values, and (b) that the flux enhancement is>10% for longer than 5 min. The warning period, from the time of the burst to the arrival of the first detectable protons in the vicinity of the earth, ranges from tens of minutes to several hours. There is a further delay of three or more hours to the time of maximum proton flux. Since only one frequency is involved, a proton warning solar radiometer could be fitted to any aeroplane, satellite, or spacecraft to supplement ground observa

ISSN:0148-0227    

DOI:10.1029/JA075i034p06940

年代:1970

数据来源: WILEY

摘要:

A small grazing incidence monochromator on the Oso 4 spacecraft has monitored variations in the absolute intensity of a 10‐A band of the solar EUV spectrum centered on the helium II Lyman α line at 304‐A during the periods October to December 1967 and June 1968 to December 1969. Measurements were also made during these periods of the absolute intensity of the solar hydrogen Lyman α line at 1216 A. The instrument was recalibrated after eighteen months in orbit by comparison with sounding rocket spectrometers and showed no loss of efficiency in the helium II mode of operation. The mean observed value of the helium II Lyman α line intensity was 8.8×109photons/cm²/sec (estimated photomeric accuracy ±30%) with long‐term variations of up to 20% from the mean value and short‐term flux increases of up to 25%. The observed value of the hydrogen Lyman α line intensity remained essentially constant at 3.6×1011photons/cm²/ sec (±30%). Ground‐based measurements of solar activity are seen to be poor indicators of the level of the solar EUV flux with the general level of the observed helium II Lyman α line intensity following most closely variations in the rel

ISSN:0148-0227    

DOI:10.1029/JA075i034p06950

年代:1970

数据来源: WILEY

摘要:

Measurements of solar extreme ultraviolet radiation in the wavelength range 1310–270 A have been made from the satellite Oso 3. The flux variation over a solar rotation period was obtained for emission lines representing elements in various stages of ionization. Since no correction need be made for atmospheric absorption, the accuracy of these results is superior to the accuracy of the results we previously obtained with similar instrumentation aboard rocket vehicle

ISSN:0148-0227    

DOI:10.1029/JA075i034p06959

年代:1970

数据来源: WILEY

摘要:

The absorption predicted by four current models of the earth's hydrogen geocorona is compared with the absorption obtained by analyzing the solar H Ly α spectrograms taken on an Aerobee rocket flight. Comparison shows that within the limits of observational error and theoretical assumptions, the data are consistent with all the models tested

ISSN:0148-0227    

DOI:10.1029/JA075i034p06966

年代:1970

数据来源: WILEY

摘要:

Observations of the geocoronal hydrogen absorption feature at the center of the solar Lyman α emission line, together with previously published absorption measurements, are analyzed and compared with the predictions of the Kockarts and Nicolet model and the Liwshitz model of the terrestrial hydrogen distribution. The results show that the hydrogen density at 100 km is between 1.25 and 2×107cm−3(for the Kockarts and Nicolet model) for a wide range of exospheric temperatures, that the geocoronal hydrogen abundance decreases with increasing exospheric temperature, that there is reasonable agreement with near‐simultaneous satellite Lyman α airglow observations, and that the absorption data are not accurate enough to distinguish between the models. Measurements of atomic hydrogen with mass spectrometers give densities that are larger by 2 orders of magnitude and therefore must be rejected in favor of the optical r

ISSN:0148-0227    

DOI:10.1029/JA075i034p06969

年代:1970

数据来源: WILEY