Stars with non-periodic Algol-type minima are members of a small
subclass of young stars selected by Hoffmeister (1949), Parenago (1954)
and others. It includes some Herbig Ae/Be (HAEBE), T Tauri stars (TTSs)
and few stars with an unclear evolutionary status (e.g. RZ Psc). There
is a growing observational evidence that their unusual photometric and
polarimetric activity is the result of variable circumstellar (CS)
extinction in an edge-on CS dust disc (Grinin et al. 1991). A recent
finding of variable redshifted absorption components in the sodium
resonance lines in the spectrum of UX Ori (Grinin et al. 1994) supports
the assumption that we deal with young progenitors of beta Pictoris
type stars, in which the spectral variability is caused by evaporation
of the comet-like bodies and solids in the vicinity of the star (Beust
et al. 1991). To find direct observational evidence of matter evaporated
from comet-like bodies is the goal of our project.

References:
Beust, H., Vidal-Madjar A., and Ferlet, R. 1991, A&A, 247, 505
Grinin, V.P., Kiselev, N.N., Minikhulov, N.X., Chernova, G.P.,
        Voshchinnikov, N.N., 1991, Ap. Sp. Sci., 186, 283
Grinin, V.P., The, P.S., de Winter, D., Giampapa, M., Rostopchina, A.N.
        Tambovtseva, L.V., van den Ancker, M. 1994, A&Ap, in press
Hillenbrand, L.A., Strom, S.E., Vrba, F.J., Keene, J. 1992, Ap.J.,
        397, 613
Hoffmeister, C. 1949, Astron. Nachr. 278, 24
Parenago, P.P., 1954, Trudi Astron. Sternberg Instit. 25
Rydgren, A.E., Cohen, M. 1985, in Protostars and Planets II, (eds.)
        D.C.Black and M.S.Mattews, University of Arizona Press, Tuckson,
        Arizona, p.371
Weaver, H.R., Mumma, M.J., Larson, H.P. 1991, in "Comets in the Post-Halley
        Era", Eds R.L.Newburn, Jr. et al. Vol. 1, 93