Optical spectra of five UX Orionis-type stars

We present in this paper several high resolution (R = 27 000) spectra of fi ve UXORs (UX Ori, CQ Tau, BF Ori, RR Tau, WW Vul), which cover the entire v isual range, from 3900 to about 8700 Angstrom. There are between 4 and 7 sp ectra per star, obtained over a time interval of two years. Simultaneous or quasi-simultaneous photometric observations were also obtained at the Crim ean Astrophysical Observatory. The complete, reduced and normalized spectra are available in electronic form. We show for each star a selection of the most interesting lines, and the full spectrum of UX Ori computed by averag ing the spectra obtained when the star was at maximum light. For UX Ori we show also the synthetic spectrum and provide an identification of most of t he lines. The spectra are too sparse to form true time sequences; however, they provide an extremely useful database for studies of UX Ori-type stars. We discuss briefly the main features of the spectra. We show that they con tain many time-stable photospheric lines that can be described to a good ap proximation by the synthetic spectra of normal A stars with log g = 3.5-4 a nd we derive for each star effective temperature, gravity and rotational ve locity. We examine the time variability of selected lines and study their c onnection with the photometric activity of the stars. Two different types o f spectral variability are identified. One is common to all stars with circ umstellar (CS) gas and is caused by perturbations of the physical and kinem atic conditions of the emitting region. There is no correlation between thi s type of activity and the brightness variations of the star. On the contra ry, a second type of spectral variability correlates well with the brightne ss variations and is very likely connected with the screening effect of an opaque dust cloud which sporadically intersects the line of sight. This typ e of variability has been observed in its simplest form in one of the RR Ta u spectra, where the equivalent width of the forbidden line [O I] 6364 Angs trom increased by a factor of about three as the star faded by approximatel y the same amount.