A search for faint violet stars

296 faint violet stars (with U - B < - 0 1:1 6) were found on U, B plates in 540 square degrees. Of these, 43 were measured photoelectrically in UBV and of those 43, 25 were measured also in a red colour R'. Two-colour diagrams in (U- B, B - V), (17 - B, V - R') and (B - V, V - R') of the measured stars were studied. Two stars (Nos. 48, 288) show very strong infra-red as well as ultra-violet and these may well be quasi-stellar galaxies. From the space distribution of the violet stars, we expect white dwarfs to be prevalent in our material. However, about a dozen quasi-stellar galaxies can be expected to be present as well. Chapter I deals with the earlier surveys for faint blue stars. Completeness of the surveys, methods used and types of stars involved are discussed. Chapter II gives a description of the observations made by the author with a discussion on the methods used to search for faint violet stars. It also includes the photoelectric results of the sampled violet stars. Chapter III discusses colours of stars found in this type of survey. A two-colour diagram in (U - B, B - V) of known hot subdwarfs (0 - B), white dwarfs quasi-stellar objects, blue horizontal-branch stars and subdwarfs (F - 0) is studied. To try to single out extra-galactic objects among the violet stars, two colour diagrams in (U - B, B - V), (U - B, V - RI) and ‚Äö (B - V, V - R i ) are studied. In chapter IV estimates are given of the expected yield of this survey as deduced from the space distribution of the types of stars concerned.