THE LIGHT CURVE OF COMET IKEYA-SEKI 1968 I MORRIS, CHARLES S.; BORTLE, JOHN E.
Publications of the Astronomical Society of the Pacific,
04/1973, Letnik:
85, Številka:
504
Journal Article
Recenzirano
The results of a reduction of 243 visual and photoelectric magnitude estimates of Comet Ikeya-Seki 1968 I are presented. These results indicate that Comet Ikeya-Seki was an intrinsically bright ...comet. A detailed study of the light curve of this comet shows that before and after perihelion there were fairly large variations in the brightness of the comet. Around perihelion, however, the brightness of the comet was almost constant.
Properties of the variations in the interplanetary magnetic field observed between August 27 and November 15, 1962, are described. A heliocentric spherical polar coordinate system is employed. The ...polar axis is the sun's axis of rotation. The field is described in terms of the vector components, Br, Bθ, and Bϕ, in this system. It is shown that the amplitude distributions of the magnitudes of the vector components of the field, taken over periods of a single field polarity, are roughly Gaussian. The widths of the distributions yield variances of 5.8, 10.0, and 10.0 γ2 for Br, Bθ, and Bϕ, respectively. Note that the variance in the direction radial from the sun is significantly smaller than the variances in either of the two transverse directions. Estimates of the power spectra for each of the three vector components are given over the frequency range 1.16–1160 cycles per day (cpd). Comparison of the spectra shows that variations in the radial direction are weaker than those in the θ and ϕ directions over the entire frequency range. The various ratios of the power densities of Br, Bθ, and Bϕ are shown to be roughly independent of frequency. The power densities in the spectra are steeply decreasing functions of the frequency with a dependence between ƒ−1 and ƒ−2 between 100 and 500 cycles per day. Beyond 500 cpd the power densities are usually below 9.1 γ2/cps, the system noise level. Estimates of the cross spectra of the various pairs of field variables are given over the same frequency range, 1.16–1160 cpd. Significant coherences are established, and the phase relationships are described. Estimates of the cross spectra of Br, Bθ, and Bϕ with the plasma velocity are given over the frequency range 1.16–116 cpd. Significant coherences are established for these pairs of variables as well, and the phase relationships are described also.
