On the origin of galactic gamma-rays
Critical review of theories on galactic gamma ray sources in view of recent 21-cm radio observations
Stecker, F. W.↗
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Dynamics of the Perseus cluster of galaxies
Radio observation for radial velocities in center region of Perseus cluster of galaxies
Chincarini, G.↗
Interpretation of interplanetary scintillations
Interplanetary scintillation radio observations interpretation by theory for atmospheric scintillations optical observations
Young, A. T.↗
Discussion of the reliability of electron densities and energies interpreted from data and limits on the proton energy and density
Analysis of radio observations of Jupiter were changed to take into account the antenna resolution. A dipole magnetic field with a surface equatorial value of 7 gauss is assumed. The electron temperature is found to increase for r 2.5 Jupiter radii with decreasing r as 1/r cubed, reaching a peak of about 100 MeV at r = 2.5 Jupiter radii. For r 2.5 Jupiter radii, the electron temperature goes as r to the 6th power because of energy lost to radiation. The consequences of making an upper estimate on the proton flux by assuming the magnetic field is loaded with all the energetic protons it can hold are described. The upper limits of proton energy, density, flux, and energy flux are calculated for 1, 2, 2.5, 3, and 6 Jupiter radii. The proton energy and velocity estimates are considered to be fairly reliable; the upper limit to the number density is probably much higher than actuality.
Beard, D. B.↗
The magnetic field structure in the active solar corona.
The structure of the magnetic field of the active solar corona is discussed with reference to optical and radio observations of the solar atmosphere. Eclipse observations provide evidence of fine scale structures in the solar atmosphere that appear to relate to the coronal magnetic field. The coronal magnetic field used for comparison is calculated from potential theory; the influence of solar activity upon the potential theory field is discussed with reference to observations of the Faraday rotation of a microwave signal from Pioneer 6 as it was occulted by the solar atmosphere. Evidence has been found suggesting the existence of expanding magnetic bottles located at 10 solar radii above flaring active regions. The dynamics of these events is discussed. It is further suggested that these magnetic bottles are an important component in the solar corona.
Schatten, K. H.↗
Narrow band characteristics of Jovian L-bursts.
Review of some radio observations of Jupiter made during three recent apparitions using several receivers, each tuned to a slightly different frequency close to 18 MHz. Sequences of oppositely polarized bursts have been observed and also differences in polarization mode between channels 400 kHz apart. Occasionally, isolated bursts of durations of 1 to 2 sec have been found to show real drifts in frequency, as distinct from the apparent drifts shown by changing intensity across a group of features.
Barrow, C. H.↗
Ephemeris of a highly eccentric orbit - Explorer 28.
An ephemeris has been obtained for Explorer 28 (IMP 3) which agrees well with 2 years of radio observations and with SAO observations a year later. This ephemeris is generated over the 3 year lifetime by a numerical integration method utilizing a set of initial conditions at launch and without requiring further differential correction. Because highly eccentric orbits are difficult to compute with acceptable accuracy and because a long continuous arc has been obtained which compares with actual data to a known precision, this ephemeris may be used as a standard for computing highly eccentric orbits in the earth-moon system. Orbit improvement was used to obtain the initial conditions which generated the ephemeris. This improvement was based on correcting the energy by adjusting the semimajor axis to match computed times of perigee passage with the observed. This procedure may generate errors in semimajor axis to compensate for model errors in the energy; however, this compensation error is also implicit in orbit determination itself.
Lowrey, B. E.↗
Energy budget in coronal holes.
EUV and radio observation, supplemented by other data, have made it possible to determine the flux of energy, F sub c, conducted from the corona into the chromosphere. Of the mechanical flux input in the corona, F sub m (of which F sub c is a large fraction), there are no direct measurements but limits can be found to it. It is shown that, if the described quantities relative to quiet regions are compared with the same quantities as observed in regions of different activity, it is possible to obtain important information on the regions of origin of the solar wind. In particular, it is found that the regions of very low EUV emission, i.e., the so-called coronal holes, appear to be the source of high energy streams of solar wind.
Noci, G.↗
Molecule formation in normal clouds
Some aspects of molecule formation in normal interstellar clouds, i.e., clouds having particle densities of less than 100 per cu cm, are discussed in light of recent studies. It is pointed out that, with their relatively large depletion parameter values (DPVs), CH clouds are 'young', whereas OH clouds have small DPVs and are 'old'. The theoretical reason for this is that OH, as a product of grain catalysis, persists over a much longer period of cloud evolution, whereas CH(+), CH, and CN, as products of gas-phase reaction, can be found only in 'young' clouds where depletion has not yet occurred. This may explain why OH has not been seen in radio observations of regions where CH(+), CH, and CN have been seen optically.
Aannestad, P. A.↗
The rings of Saturn
The upcoming Mariner Jupiter-Saturn '77 space project is discussed. The variations in radar and radio observations are evaluated, along with particle distribution within the Saturn rings.
Palluconi, F. D.↗
Estimates of the size of particles in Saturn's rings and their cosmogonic implications
Near infrared ice band measurements, radar and radio observations, and implications of the size estimates of particles in Saturn's rings are discussed. The measurements are compared to the Poynting-Robetson effect and a possible mechanism by which the size of the particles may significantly change after the initial formulation of the material in the rings is proposed.
Pollack, J. B.↗
The solar elogation distribution of low frequency radio bursts
Over 500 days of low frequency (less than 5 MHz) radio observations from the IMP-6 spacecraft were accumulated to produce a two dimensional map (frequency versus elongation) of solar type III burst occurrences. This map indicates that most solar bursts are emitted at the second harmonic of the plasma frequency rather than the fundamental. The map also shows that the solar wind electron density varies.
Kaiser, M. L.↗
Radio and gamma ray evidence for a molecular-arm feature at 5 kpc from the galactic centre
Recent measurements of the galactic CO distribution as evidenced from 2.6 mm radio observations of the CO emission line intensity are correlated with the SAS-2 measurements of galactic gamma ray emission. Both distributions are indicative of a ring-shaped distribution or arm consisting of cool clouds of molecular hydrogen at a galactocentric distance of approximately 5 kpc. The mean density of H2 in this region is estimated to be between 1 and 5 cu cm. Both a galactic and extra-galactic origin of cosmic rays are consistent with the observations, although the presence of dynamical effects and increased star formation at 5 kpc in the dense molecular clouds may be connected with an increase in cosmic-ray production.
Solomon, P. M.↗
Confrontation of Lemaitre models and the cosmological constant with observations
The history of the cosmological constant and the Lemaitre models is reviewed briefly. Using recent cosmological observations, it is found that the cosmological constant if nonzero must be in absolute value less than 2 times 10 to the negative 56th power per sq cm. The predictions of the Lemaitre models are compared with modern observations. It is shown that Lemaitre models without evolution fail to reproduce the observed radio source counts. The existence of quasars with large redshift (z greater than 2.5) is shown to be strong evidence against the Lemaitre models.
Petrosian, V.↗
Studies of the infrared source CRL 2688
Infrared, optical, and radio observation are described of a newly discovered galactic infrared source. Most of the radiation comes from a 1.''5 diameter infrared source at a temperature of about 150 K, but some visible emission in the form of a symmetrical highly polarized reflection nebulosity is also seen. The object could represent either a very early or a very late stage in stellar evolution.
Ney, E. P.↗
The solar elongation distribution of low-frequency radio bursts
Over 500 days of low-frequency (less than 1 MHz) radio observations from the IMP-6 spacecraft have been accumulated to produce a two-dimensional map (frequency vs elongation) of solar type III burst occurrences. This map indicates that most solar bursts in this frequency range are observed at the second harmonic of the plasma frequency, rather than the fundamental. The map also shows that the solar wind electron density varies as an inverse power of heliocentric distance, with the exponent somewhat less than 2 to perhaps 3 or higher.
Kaiser, M. L.↗
Optical, infrared and radio studies of compact H II regions. I - The complex in S 106
The paper reports on combined optical, infrared, and radio observations of the compact complex S 106. The source could be resolved into ten components, three of which are compact components of size approximately 0.2 pc and were detected at 12.6 microns and 2.7 GHz. Two of the components are point-like sources detected at 8000 A. One of the components detected at 8000 A is spatially coincident with a strong 3.5 micron source and is suggested as a possible exciting star for the complex.
Pipher, J. L.↗
The relationship between the galactic matter distribution, cosmic ray dynamics, and gamma ray production
Theoretical considerations and analysis of the results of gamma ray astronomy suggest that the galactic cosmic rays are dynamically coupled to the interstellar matter through the magnetic fields, and hence the cosmic ray density should be enhanced where the matter density is greatest on the scale of galactic arms. This concept has been explored in a galactic model using recent 21 cm radio observations of the neutral hydrogen and 2.6 mm observations of carbon monoxide, which is considered to be a tracer of molecular hydrogen. The model assumes: (1) cosmic rays are galactic and not universal; (2) on the scale of galactic arms, the cosmic ray column (surface) density is proportional to the total interstellar gas column density; (3) the cosmic ray scale height is significantly larger than the scale height of the matter; and (4) ours is a spiral galaxy characterized by an arm to interarm density ratio of about 3:1.
Kniffen, D. A.↗