The B[e] phenomenon can be present in stars of different types and at different evolutionary stages. Very extended circumstellar matter prohibits the study of the atmosphere of these stars, since no photospheric lines are usually observed. Standard stellar atmosphere models are thus not applicable when determining stellar parameters. One of a few possibilities for comprehending the nature of these objects is to study their time variations. Unfortunately, almost no set of spectra with an adequate time description is available for these objects. We obtained an extensive set of MWC 342 spectra (102) We detected variability in the spectral lines on both short and long time scales. He i 6678 Å shows day-to-day changes in its line profile. We observed pure absorption, pure emission, the P Cygni profile, and the inverse P Cygni profile in this line. There are time intervals where this line disappeared. The Hα line also shows considerable changes in its line profile, radial velocities, and equivalent widths. A cycle of about 1560 days was detected in its radial velocities. The detailed description of the variations in MWC 342 spectra reveals its important properties. The inner atmosphere is affected by changes of days, while existing long-term waves are propagated into the outer regions. It is highly probable that the continuum radiation in the visual region is also variable. The inverse P Cygni profile was probably observed when the continuum radiation reached its maximum. These properties indicate the complicated nature of this object. We discuss here a possible explanation of the observations by a stellar wind supported by pulsations.

We present results of nearly six years of spectroscopic observations of the B[e] star V2028 Cyg. The presence of the cold-type absorption lines combined with a hot-type spectrum indicate the binarity of this object. Since B[e] stars are embedded in an extended envelope, the usage of common stellar atmosphere models for the analysis is quite inappropriate. Therefore, we focus on the analysis of the long-term spectral line variations in order to determine the nature of this object. We present the time dependences of the equivalent width and radial velocities of the Hα line, [O i] 6300 Å, Fe ii 6427, 6433, and 6456 Å lines. The bisector variations and line intensities are shown for the Hα line. The radial velocities are also measured for the absorption lines of the K component. No periodic variation is found. The observed data show correlations between the measured quantities, which can be used in future modelling.

We present an alternative model of V2028 Cyg, a B[e] star of FS CMa type. The star V2028 Cyg is atypical among FS CMa stars due to its composite spectra of B4III and K2II-Ib type. Our modelling of the temporal variability of the Hα line bisectors indicates as the most probable model a geometrically and optically thick disc, which is surrounded by a dusty ring seen almost edge-on. This provides a possibility that the K-spectral component is formed in the disc.