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Periodic variations in Davis' experimental data concerning the solar neutrino capture rate are derived on the basis of a Fourier spectrum analysis. Variations in the 37Ar production rate are obtained for a series of randomly spaced observations in the period 1970-1985 (runs 18-89). The harmonic analysis of runs 18-89 has determined solar neutrino capture rate variations with periods of 8.33, 5.00, 2.13, 1.61, 0.83, 0.61, 0.54, and 0.51 yr, thereby confirming earlier calculations performed for the set of runs 18-69 (1983), 18-74 (1985a), and 18-80 (1985b). The results also confirm those of Sakurai (1979) who showed that there is strong evidence that the observed solar neutrino flux has a tendency to vary with quasi-biennial periodicity. We show that the results of the Fourier spectrum analysis do not depend upon certain high or low values in Davis' experimental data.

Since 1971 the magnetic Ap star 52 Her has been investigated with respect to its magnetic field and radial velocity on the observational basis of 140 photographic Zeeman spectrograms obtained at the 2m-telescope in Tautenburg. Additionally. 47 normal spectrograms were used for the determination of the radial velocity only. The technical foundation for observation and measurement is considered. The main purpose of the paper, however, is the documentation of the observations and the measuring results. Deductions drawn from the material assorted here or taken from other sources are put off to following papers.Der magnetische ApStern 52 Her wird seit 1971 hinsichtlich seines Magnetfeldes und der Radialgeschwindigkeit auf der Grundlage des Beobachtungsmaterials von 140 photographischen Zeeman-Spektrogrammen untersucht, die am 2m-Teleskop in Tautenburg gewonnen wurden. Zusatzlich standen fur die Bestimmung der Radialgeschwindigkeit noch 47 Normalspektrogramme zur Verfiigung. Die technischen Grundlagen der Beobachtung und Messung werden diskutiert. Der Hauptzweck der Mitteilung besteht jedoch in der Dokumentation der kobdchtungen und Me& ergebnisse. Folgerungen aus dem hier mitgeteilten bnv. aus anderen Qwllen stammenden Material werden in nachfolgenden Arbeiten gezogen. 1.Mauna Kea dates (300 Gauss). A search for periods by the method of LAFLER and KINMAN (1965) yielded two acceptable periods; 3.8575 d and 3.878 d. The first one was preferred by the authors, because in this case the values of the intensity of the CaII(K) line (3933 A) fit better with the magnetic data in a phase diagram. A period of 3.850 d was already revealed by WINZER (1974), who investigated the variztions of the brightness of the star in the B and V bands. Later on that period was corroborated by MUSIELOK (P = 3.900 d, private communication). WOLFF and PRESTON (1978) supposed that the variation of the magnetic field strength by a period of nearly 4 days is produced by the rotation of the star and concluded therefore on the validity of the oblique rotator model. The angle between the axes of the rotation and the magnetic dipole was determined to maximally 26 deg, i.e., the axes being nearly parallel. The inclination angle i between the line of sight and the rotation axis is assumed to i > 35 deg. The radial velocities determined from all plates give a mean of RV = (0.2 f 0.5) km/s, but no phase-dependend variation could be detected. BORRA and LANDSTREET (1980) published 6 photoelectrically determined values of the magnetic field strength of 52 Her. Also these values are permanently positive and can be compared in magnitude with the photographical ones from Mauna Kea, not accounting for the different observational methods applied respectively.

New measurements of the effective magnetic field of the supergiant v Cep confirm the earlier finding of the temporary presence of a magnetic field larger than lo00 Gauss. The observations were obtained using photographic and photoelectric methods. Searching for periods yields as the best representation of the Beff values (related to 3 cycles) the period 4.7 years. Magnetic field measurements in early-type luminous stars are reported for some few stars only, the magnetic field strength being by a hundred Gauss. The observational evidence of a magnetic field in supergiants is fairly weak due mainly to spectral line variations caused by motions of different time scales within the stellar atmosphere.A supergiant of intermediate spectral type for which a magnetic field fluctuating systematically between -100 and f600 Gauss was detected is o! Car (Canopus, FOIb), RAKOSCH et al. (1977). Recently WEISS (1986) corroborated by investigations of additional but also old spectrograms for this star the existence of a magnetic field and derived for its variation a period of 6.9 days.Another remarkable magnetic supergiant is v Cep (A2Ia). In this star a magnetic field was found at first by SCHOLZ and GERTH (1980); its existence was confirmed significantly by the construction of a -, z diagram on the basis of 6 numerically superposed spectrograms relating to the intrinsic linear function on z -with A 1 being the amount of the Zeeman splitting in a longitudinal field and z the Lande factor. Using all data available at that time, a period of nearly 5 years was suggested, the data covering only one period of the variation, which has a maximum value up to f2000 Gauss and a rather flat minimum with slightly negative values of about -300 Gauss.The establishment of such a large magnetic field in a supergiant would be of great importance for investigations concerning the origin of magnetic fields in stars of this spectral class and state of development, for it has been debated since ever (DE JAGER 1980) whether a supergiant because of its violent inner motions could maintain a magnetic field generated anyhow initially, not to mention any new originating of such one. As pointed out by KRAUSE and SCHOLZ (1986), an expedient could be found by employing the dynamo theory.In our efforts to confirm the magnetic field of v Cep it was aspired to use the photoelectric method, too. During the next period further magnetic field observations have been accumulated by means of the photographic coudk spectroscopy at the 2m-telescope in Tautenburg and at the 6 m-telescope in Zelenchuk (USSR) as well as photoelectric measurements of the polarization in line wings (Zelenchuk). The magnetic field values derived from photographic spectrograms are listed in Table 1 in chronological consecution. All plates have been measured on the Modified Abbe Comparator and evaluated using computerized methods at the Astrophysical Observatory Potsdam.Subjecting this row of (only photographic) values to a search for periods (as we do by means of a Fourier transform of unequ...

Abstract. The model of the magnetic field structure of the CP2 star CU Vir (HD 124224) constructed by the method of "magnetic charge distribution" (MCD-method) has shown that it is consistent with the model of a displaced dipole. The displacement from the center of the star to the negative monopole is d = 0.3 of the radius, the inclination angle of the dipole axis to the rotational axis is β = 87 o , and the field strength at the poles amounts to Bp(−) = 7.9 kG and Bp(+) = 1.2 kG. The mean surface magnetic field varies within 1.2-3.2 kG. The dipole axis points away from the zero meridian by an angle of +30 o . Using the MCD-method we derived the distribution of the field intensity over the surface, which has been compared to the distribution of the chemical elements He and Si, taken from literature. Silicon has turned out to concentrate around the strong negative magnetic pole, whereas helium concentrates in the region of the weak positive pole, where the orientation of magnetic lines of force is mostly vertical. The presence of a double silicon spot suggests a more complex magnetic field structure than the dipolar one, however, the small number of data makes it impossible so far to confirm such an assumption.