Some features of the solar microwave emission and their connection with geomagnetic activity

The quiet component of the 9.1-cm solar radio emission is studied from the Stanford radioheliograms covering the period April–October 1964. The distribution of the brightness temperature in heliographic coordinates is not entirely uniform, but positive and negative departures from the average value appear at a number of stable locations. The most important negative departure crosses the central meridian 4 days before the maximum of the recurrent geomagnetic activity. Two out of three less important brightness depressions are connected with geomagnetic disturbances in the same manner. It is suggested that the brightness depressions are identical with M-regions.The result is confirmed by the construction of polytrope models for the solar wind, for various values of the parameters (the polytrope index) and T (the temperature in the inner corona). The velocities near the earth's orbit and in the inner corona are computed as functions of the model parameters, the density results from the observed proton flux at 1 AU. For quiet conditions the model with T = 1.26 × 10⁶ K and = 1.10 is appropriate. The corresponding density and temperature in the corona lead to a value of 4000 K for the contribution of the corona to the 9-cm brightness. For disturbed conditions the suitable model has the parameters T 2.0 × 10⁶ K, a 1.04. It being given that the proton flux at 1 AU is relatively constant, the equation of continuity leads to a low coronal density because of the high solar-wind velocity. The corresponding coronal contribution to the 9-cm brightness is of the order of 10 K. This confirms that the brightness temperature is considerably reduced in the regions where the enhanced solar wind originates. We suggest the name coronal depression for such regions.Papers II and III will appear in forthcoming issues of this journal.     

The He+ λ 4686 line in the low chromosphere

We report an unsuccessful search for the He⁺ 4686 line in the low chromosphere. However, at the location of this line we detect a number of other chromospheric emission lines. This leads us to the conclusion that the He⁺ 4686 identification made in the past, as well as other identifications, are probably in error. Additionally the region of the neutral helium 4713 line is also studied.On leave from Tokyo Astronomical Observatory, Mitaka, Japan.     

Das elliptische eingeschränkte Dreikörperproblem

Inhalt Eine einfache Herleitung der allgemeinen Gleichungen des elliptischen eingeschränkten Dreikörperproblems und der daraus folgenden linearen Variationsgleichungen mit periodischen Koeffizienten für die Bewegung in der Nähe der Librationszentren wird gegeben. Die in zwei früheren Arbeiten vorgelegte Aufspaltung der ebenen Variationsgleichungen 4. Ordnung in zwei Komponenten 2. Ordnung wird kurz rekapituliert.Bei Benützung dieser Aufspaltung wird die Bewegung in der Umgebung der Dreieckspunkte näher untersucht. Mit Hilfe einer Näherungslösung werden Frequenzverteilung und Stabilitätsbereiche bestimmt.

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A simple derivation of the general equations of the elliptic restricted Three-Body Problem is given from which immediately follow the linear variational equations with periodic coefficients describing the motion close to the libration centers. The explicit separation of these 4th order planar variational equations into two 2nd order components is shortly repeated.Using this separation the motion in the neighborhood of the equilateral points is investigated in more detail. An approximate solution is determined giving frequency distribution and stability domains.

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Gehalten vor der Konferenz über Celestial Mechanics, Oberwolfach, Germany, August 27–September 2, 1972.     

Interference in solar oscillations

We have analyzed magnetograph observations of the 5-min oscillations. We find that most of the oscillatory power is concentrated in space and frequency. Interference effects where these concentrations overlap can explain some of the variations in amplitude of the oscillation.Of the National Bureau of Standards and University of Colorado.     

Photometric and spectrophotometric observations of Nova Delphini 1967

Photographic, photovisual and photoelectric (V) observations of Nova Delphini 1967 were made from August 8 to October 31 (Table I, Figure 1). Simultaneously spectrophotometric measurements of the continuum were made on objective prism exposures extending to November 26, and spectrophotometric gradients derived (Tables II and III; Figures 3, 4, and 5). The continuum of Nova near its flat maximum is close to that of an early-type star in contrast to late-type absorptionline spectrum.     

High-resolution measurements of photosphere and sunspot velocity and magnetic fields using a narrow-band birefringent filter

Modifications to a Zeiss 1/4 Å filter are described which allow high spatial resolution observations of the line-of-sight velocities and magnetic fields in the photosphere and in sunspots. First results show: (1) the granular velocity field to be very strong; differences in upward motions in the granules and downward motions in between are as much as 6 km/sec; (2) the Evershed effect in sunspots to originate primarily in the dark regions between bright penumbral filaments.     

The scattering mean free path in the Uranian atmosphere

New measurements of the equivalent widths of the 4-0 S(0) and S(1) H₂ quadrupole lines in the Uranian spectrum have been obtained using high dispersion (4.12 Å/mm) image-tube spectrography. The measured equivalent widths are $\text{62 ± 19}\text{m}\text{A}\text{?}\text{and}\text{58 ± 13}\text{m}\text{A}\text{?}$ for the S(0) and S(1) lines, respectively. Curve-of-growth analysis in terms of a reflecting layer model yields an H₂ column-density of 780_?330⁺⁹⁴⁰km amagat and a temperature of 78_?24⁺⁸⁰°K. Interpretation using a semi-infinite, homogeneous, isotropically scattering model for line formation yields a scattering mean free path at λ6400 Å of 550 ± 250 km amagat. Quoted errors for both the H₂ column-density and the scattering mean free path include the effect of uncertainty in the choice of atmospheric temperature. The results are discussed in terms of current models for the Uranian atmosphere.     

Theoretical ion densities in the lower ionosphere

We have solved the coupled momentum and continuity equations for NO⁺, O₂⁺, and O⁺ions in the E- and F-regions of the ionosphere. This theoretical model has enabled us to examine the relative importance of various processes that affect molecular ion densities. We find that transport processes are not important during the day; the molecular ions are in chemical equilibrium at all altitudes. At night, however, both diffusion and vertical drifts induced by winds or electric fields are important in determining molecular ion densities below about 200 km. Molecular ion densities are insensitive to the O⁺ density distribution and so are little affected by decay of the nocturnal F-region or by processes, such as a protonospheric flux, that retard this decay. The O⁺ density profile, on the other hand, is insensitive to molecular ion densities, although the O⁺ diffusion equation is formally coupled to molecular ion densities by the polarization electrostatic field. Nitric oxide plays an important role in determining the NO⁺ to O₂⁺ ratio in the E-region, particularly at night. Nocturnal sources of ionization are required to maintain the E-region through the night. Vertical velocities induced by expansion and contraction of the neutral atmosphere are too small to affect ion densities at any altitude.