Upper Main Sequence Stars with Anomalous Abundances: Proceedings of the 90th Colloquium of the International Astronomical Union, Held in Crimea, U. S. S. R. , May 13-19 1985

This volume contains papers presented at IAU Colloquium No. 90. at the Crimean Astrophysical Observatory in May of 1985. A few additional contributions are included from authors who for various reasons were unable to attend the meeting. Four years have passed since the last major international conference on chemically peculiar stars of the upper main sequence was held in Liege. Belgium in 1981. Previous conferences were held in 1975 (Vienna. Austria) and in 1965 (Greenbelt. Maryland. USA). As the proceedings of this Colloquium show. the recent availability of ultraviolet spectra of large numbers of normal and chemically peculiar A and B stars is having a major impact on the way we study these objects. and has led to many new. exciting and unanticipated results. Simultaneously. the more traditional study of optical spectra has been advanced through the increasing use of very high spectral resolution with high signal-to-noise detectors. The chemically peculiar (CP) stars on the upper main sequence belong in the standard framework within which we understand stellar evolution and the history of matter. Recent work has made it clear that the unusual chemistry and magnetic structure of these objects is of relevance across the broad domain of stellar astronomy. from the upper main sequence to horizontal branch stars and white dwarfs. Metal poor (J>. Boo) as well as metal rich (Ap. Am) stars are an integral part of the picture. Front Matter....Pages i-xiv The Origin and Structure of the Magnetic Fields of the Chemically Peculiar Stars....Pages 1-10 Origin of the Magnetic Field....Pages 11-24 On the Spottedness, Magnetism and Internal Structure of Stars....Pages 25-28 Investigations of the Magnetic Fields of Chemically Peculiar Stars of Different Age....Pages 29-32 The Magnetic Field and other Parameters of the Chemically Peculiar Stars....Pages 33-36 On the Perturbation Technique for the Influence of Magnetic Field on Stellar Oscillations....Pages 37-40 On the Magnetic Field of β CrB....Pages 41-44 Discussion....Pages 45-47 Does ν Cep Indicate a Non-axisymmetric Dynamo?....Pages 49-49 Model Atmospheres and Radiative Transfer in Chemically Peculiar Stars: Interpretational Significance of Non-LTE....Pages 51-56 Influence of the Magnetic Field on the Polarization of Radiation Scattered by Electrons in Stellar Atmospheres and Envelopes....Pages 57-79 A Determination of Magnetic Fields of T Tau and Ae/Be Herbig Stars using the Parameters of their Linear Polarization....Pages 81-86 Practical Problems in the Analysis of CP Stars....Pages 87-90 Missing Levels and Lines of Astrophysical Importance....Pages 91-98 Characteristic Absorption Features in the Spectra of Ap-Si Stars Between 1250 and 1850 Å....Pages 99-104 Space Observations of Chemically Peculiar and Related Normal Stars....Pages 105-107 Study of Inhomogeneities on the Surface of Magnetic CP Stars....Pages 109-123 Inverse Problems in Astrophysics....Pages 125-134 The Distribution of Fe, Cr, and Si over the Surface of θ Aur....Pages 135-136 Application of Deutsch’s Method for 53 Cam....Pages 137-140 The Nonhomogeneous Distribution of Abundances and the Magnetic Field Measurements in CP Stars....Pages 141-147 Systematics of CP Stars....Pages 149-149 Spectroscopy of CP Stars in the Groups of Different Age....Pages 151-158 Rotation, Variability and Age of Ap Stars....Pages 159-166 Light curve analysis of rotating variable stars....Pages 167-170 A Search for Long-Term Photometric Variability in CP2-Stars....Pages 171-174 The Nature of Balmer Line Variability in Chemically Peculiar Stars....Pages 175-177 The Variability of the λ5200 Feature in CP2 Stars....Pages 179-181 Short time light variations of Ap-stars....Pages 183-187 CP-Stars in the Near Infrared: Normal!....Pages 189-190 Hα and OI Photometry of Upper Main Sequence Stars with Anomalous Abundances....Pages 191-194 A Photometric Investigation of the Magnetic Star 53 Camelopardalis....Pages 195-198 Spectrophotometry of the Broad Continuum Features in Magnetic Ap Stars....Pages 199-199 On the Duplicity of CP3 Stars....Pages 201-204 Investigations of CP and Normal Stars with Coadded Dominion Astrophysical Observatory Spectrograms....Pages 205-208 Rapid Oscillations of CP2-Stars....Pages 209-217 Computed Spectral Line Variations for Oblique Nonradial Pulsators....Pages 219-233 Short-Periodic Radial Velocity Variations of the B9p Star ET And....Pages 234-234 Frequency Analysis of the Rapidly Oscillating Ap Star HD 60435....Pages 235-238 Investigations of the Magnetic Star 53 Cam Variations using the Spectra of High Time Resolution....Pages 239-242 HD 24975: A New Delta Scuti Star? (Or a Mild Ap Star with Short Photometric Variations?)....Pages 243-252 Hot Magnetic Stars Abundances, Spectroscopy, Photometry, Systematics....Pages 253-256 On the Ultraviolet Photometric Variability of the Helium-Weak B Stars (From ANS Data)....Pages 257-269 Intermediate Peculiar Stars : The Bp-Ap Si Stars....Pages 271-274 Blanketing Hypothesis and Light Variations of HD 27309....Pages 275-290 A Spectroscopic Study of the Bp-Star θ Aur....Pages 291-294 The Ultraviolet Spectral Energy Distribution of the Magnetic Ap Star HD 170000 Inside and Outside of the Spots....Pages 295-298 Cool Magnetic CP Stars....Pages 299-304 Abundance Analysis of Three Ap Stars: HD2453, HD8441, and HD192913....Pages 305-317 Absorption Lines of CaII and H in the Near IR Region of the Magnetic Star HD 152107....Pages 319-322 A Search for Heavy Elements in the Ultraviolet Spectra of Ap Stars....Pages 323-326 The Investigations of Variations in the Depression λ 4200, λ 5200 of the Magnetic Stars 53CAM and Beta CrB.....Pages 327-340 Discussion....Pages 341-344 The age of ε UMa....Pages 345-345 Line Spectrum Variations in the AP Star HD 5I4I8....Pages 347-350 βCrB — a Rosetta stone?....Pages 351-354 Some Structural Features of Magnetic Fields of the Chemically Peculiar Stars β Cr B and α 2 CVn....Pages 355-358 β Lyrae — A Binary System with Anomalous Abundances and Magnetic Field....Pages 359-363 Spectroscopic Analyses of Hot Main Sequence Stars....Pages 365-368 Diffusion Processes and Chemical Peculiarities in Magnetic Stars....Pages 369-380 Chemical and Temperature Inhomogeneities on Stellar Surfaces as a Result of an Instability....Pages 381-393 Non-Magnetic Intermediate-Temperature Stars: A Review....Pages 395-396 The Abundance of Gallium in B-Type Chemically Peculiar Stars....Pages 397-419 Gallium Overabundance in the Ap-Si Star HD 25823....Pages 420-420 The Most Iron-Deficient Manganese Star HR562....Pages 421-424 The Light and Spectrum Variable CP2 Star HR 6127....Pages 425-428 The Analysis of Chemical Composition of Am Star Atmospheres....Pages 429-432 Lithium in Am and δDel Stars....Pages 433-445 The LI I 6708 Feature in CP Stars....Pages 447-450 The Metallic-Lined Star 32 Aquarii....Pages 451-453 Particle Transport in Non-Magnetic Stars....Pages 455-457 The Planetoid-Impact Hypothesis of CP, F, A, and B Star Formation: Possibilities and Perspectives....Pages 459-472 Back Matter....Pages 473-478 ....Pages 479-489