[en] The aim of this investigation is to give a possible description of the strong variations in the light curve of the star. Therefore, a new period was derived for each different cycle by the Lafler-Kinman method. Unfortunately, due to the small number of data in the data sets these newly-derived periods have an error of about 0.1 day. (Auth.)

[en] In order to avoid the violation of basic principles of macroscopic reversibility and detailed balance, the authors propose a cell kinetic model for atom-photon interactions instead of Einstein's classical photon kinetic mechanism. This model can be interpreted as a generalization of either mass action law or Einstein's original scheme. 11 refs., 2 figs., 1 tab

[en] A recent paper (Olah et al., 1985) showed that the active areas of HK Lac exhibited sometimes small and sometimes large scale motions. In the case of the Sun it is well known that new spots exhibit large proper motions while the old ones move almost together with the surrounding photosphere. On HK Lac both a newly formed active area and an existing old one showed concurrent rapid motions. A possible interpretation of this phenomenon is that new spots appeared in both the new and the old active areas simultaneously. This time coincidence may be accidental but if spots originate in deeper layers, then spots of common deep origin may appear in remote places of the stellar surface at the same time. Similar phenomena are seen on the Sun when there is simultaneous emergence of new flux in various parts of an extended active region (Zirin, 1983). The distribution of the active areas on the surface of HK Lac during the past eight years is discussed. (author). 3 figs., 10 refs