Rival theories for the origin of the magnetic fields present in the CP stars are discussed, particular attention being paid to the claims of the ‘contemporary dynamo’ and ‘fossil’ theories. The internal structure of the field as predicted by calculations consistent with the fossil theory is discussed at length. It seems that current time dependent models can now give a coherent picture of the fields of the CP stars according to the fossil theory. Dynamo theory modelling has not been developed in such detail. As yet neither the theoretical predictions nor the observational material seem to be detailed enough to allow a decisive comparison between the theories.

Some progress has been achieved in recent years in the theory of the stellar magnetic field generation but a lot of questions remain unanswered. I would like to give here a brief critical review of the current state of the problem.

It is hypothesized that kinematical structures within stellar interiors that are results of a self-organization of these interiors as thermodynamically open nonlinear systems constitute the physical basis for stellar magnetism.

The program of comprehensive investigations of stellar magnetism in the Special Astrophysical Observatory of the USSR AS includes the study of origin and evolution of the stellar magnetic fields in open clusters and associations of different age. In the papers by Borra (1981), Brown et al. (1981) and North and Cramer (1984) have been found some indications on the evolutionary decay of the fossil stellar fields.

The surface field Bs ( but not the effective Be one ) is responsible for different processes occuring in the magnetic stars atmospheres. For this reason it is natural that different investigators are interested in working out and improving methods of determination of Bs. Especially great attention attracts the method based on using the multicolor Geneva photometry. Cramer and Maeder have found a dependence between Bs and parameter Z of multicolor photometry wich they use for the estimation of the surface field. But it is necessary to investigate this method before application. Due to this reason we have put the following two problems:

A - The search for stars with a maximal predicted field

B - Examination of calibration of Bs (Z).

The modification of the Rayleigh’s principle is developed for the determination of the perturbations of the eigenfrequencies due to a weak magnetic field. The perturbational procedure is outlined, including its generalization for a slowly rotating magnetic star.

We have discussed the oscillations of the magnetic field (He) of β CrB with a period P2=P1/5=3d.6974, where P1 is stimulated by a rotation of the star. The analysis of other author’s measurements has been confirmed the reality of P2.

The curve-or-growth method of estimating the stellar surface magnetic fields is applied to six Ap stars of different temperatures and one normal (or metallic-line) star σ Aqr. The values of Hs determined by the curve-of-growth technique are in good agreement with those obtained by the photometric method.

According to observations of Scholz and Gerth the super-giant 𝓿 Cep has a magnetic field with a maximum field strength up to 2500 Gauss. This field shows a period of about 5 years. It is unplausible that this magnetic field is a relic since 𝓿 Cep was formed by expansion of a B-star. We claim here that 𝓿 Cep represents a dynamo exciting a magnetic field which in the average strongly deviates from symmetry about the rotation axis.

One of the main problems in studying chemically peculiar (CP) stars is the question of the extent to which the conceptual framework of the contemporary spectroscopic diagnostics is reliable. As the first step, it should be clarified whether the traditional assumption of local thermodynamic equilibrium (LTE) provides an adequate approximation to reality, or whether a more general non-LTE approach should be employed.

The period of rapid development of computational methods and extensive calculations of NLTE model atmospheres is now past its culmination point. The importance of a relevant NLTE description is viewed as unquestionable for hot stars (B and earlier). Consequently, the hot stars attract the attention of most “NLTE theoreticians,” while considerably less attention is being devoted to later types (late B and A). Moreover, the abundance anomalies found in the CP stars are no longer expected to be a spurious result of an inadequate (LTE) analysis (Cowley 1981). It is not commonly accepted that other phenomena such as diffusion, magnetic field, inhomogeneous abundance distribution, etc., are quite essential ingredients of the general atmospheric pattern of CP stars. Therefore, a large part of the astronomers investigating the CP stars now consider the NLTE effects to be rather minor perturbations of the LTE predictions.

The radiation scattering by electrons play an important role for stars with the surface temperature ≥ 2.104 °K. Many among these stars have magnetic fields of the order 1 - 100 G. We shall consider the role of the field for the radiative transfer in continuum spectra.

Electrons in the field form an axisymmetric medium similar to the single axis crystal. Hence, the medium will have dichroism and birefringency. If the gyrofrequency ωB is much less than the radiation frequency ω then the dichroism can be neglected. The circular birefringency can be characterized by the angle of the Faraday rotation

Attempts of applying stellar polarization spectra to evaluation of magnetic fields of some types of stars are described.

Saturation and curve-of-growth effects remain a dominant source of errors in abundance work. We suggest that the use of low noise material will enable future users to work more easily with weak lines and avoid these difficulties. The method of wavelength coincidence statistics is reviewed within the context of line identifications and abundance work. This technique is readily implemented, and should be a standard part of the analytical spectroscopy of stars. Analysis of the ultraviolet spectra of CP stars is severely handicapped by missing atomic data. Synthetic spectra are displayed showing the possible effects of hitherto unknown lines on spectra of IUE resolution.

The purpose of this paper is to make a brief survey of the knowledge of iron group elements as concerns energy levels and transition arrays in neutral and singly ionized atoms and to give rough predictions of missing levels and lines. The amount of data that have been published for these elements after the edition of the Multiplet Tables are considerable. For detailed information about sources of new data and compilations the reader is referred to the Report from Commission 14 in the Transactions of IAU. In this paper we will focus on still missing energy levels and associated missing transitions, which have to be considered in the construction of synthetic spectra.

The structure of the iron group elements is complex not only because of the filling of the 3d shell but also because of the competition in binding energy between the 3d- and the 4s electron. For a given number of valence electrons, k, we have to consider three different low configurations in the complex (3d + 4s)k having about the same energy in neutral and singly ionized atoms. In neutral atoms the 3dk−2 4s2 configuration generally occupies the ground state, while the 3dk configuration appears at rather high excitation energy. In the singly ionized atoms all three configurations have about the same energy, giving the most pronounced complexity.