Be and shell stars : symposium no. 70 (Merrill-McLaughlin memorial symposium) held at Bass River, Massachusetts, U.S.A., 15-18 September 1975

The International Astronomical Union Symposium No. 70 on Be and Shell Stars, the Merrill-McLaughlin Memorial Symposium, was held in Bass River (Cap Cod), Massachusetts, U. S. A. , from September 15th through 18th, 1975. Fifty-three astronomers from Argentina, Belgium, Canada, Czechoslovakia, France, Israel, the United Kingdom, the United States, and the Vatican attended and participated in the Symposium. This volume, which parallels the actual program closely, contains the papers presented at the Symposium plus most of the discussion following the papers. New observational techniques and fresh theoretical ideas have resulted over the past few years in a renewed interest in Be and shell stars. At IAU Symposium No. 51 on Extended Atmospheres and Circumstellar Matter in Spectroscopic Binary Sys­ tems, the Otto Struve Memorial Symposium, in Parksville, British Columbia, Canada, three years ago, a number of participants expressed the wish to organize a symposium on Be and shell stars. If we wish to identify an official 'Father of IAU Symposium No. 70', it would be Mirek Plavec who, in his capacity as President of IAU Commission 42 (Photometric Double Stars) requested and received the cooperation of Commissions 29 (Stellar Spectra) and 36 (Stellar Atmospheres), suggested an Organizing Committee, and wrote to the IAU General Secretary in 1973 requesting that the IAU Executive Committee approve the proposed confer­ ence as an IAU Symposium. Front Matter....Pages I-XVI Introductory Address....Pages 1-10 Front Matter....Pages 11-11 Spectra and Photometry of Be Stars....Pages 13-27 A Survey of Hα in the Brighter Northern Be Stars....Pages 29-29 A Study of Be Stars in Clusters....Pages 31-32 Emission Features of Several Be Stars as Related to Their Luminosity Class and Spectral Type....Pages 33-36 Rapid Variations in the Spectra of ο and, γ Cas, and χ Oph....Pages 37-40 Rapid Variations of H α in Be Stars....Pages 41-49 Stellar Photometric Observations at Hα through a Narrow-Band Interference Filter....Pages 51-58 Spectroscopic Observations of Be Stars in the near Infrared....Pages 59-65 New Observational Data Concerning 4 Her and ζ Tau....Pages 67-67 The Surface Gravities of Be Stars....Pages 69-78 A Comparative Study of the Shell of ζ Tau and 48 Lib....Pages 79-85 A Model for the Shell of HD 50138....Pages 87-93 Observations Récentes de HD 200120....Pages 95-97 Singly-Ionized Iron Emission Lines in the Spectra of Early Type Stars....Pages 99-103 Pleione as a Variable Star....Pages 105-106 Energy Distributions of Be Stars....Pages 107-119 Front Matter....Pages 121-121 Be Stars as Rotating Stars: Observations....Pages 123-136 Ultraviolet Observations of Rapidly Rotating B-Type Stars....Pages 137-137 The Relationship of the Oe to the Be Stars....Pages 139-147 Front Matter....Pages 121-121 Hα and Hβ Measures as Related to be Star Rotation....Pages 149-154 Front Matter....Pages 155-155 Radio Observations of Be Stars....Pages 157-164 Ultraviolet Observations of Be Stars....Pages 165-178 A Survey of Mass Loss from Be and Shell Stars Using Ultraviolet Data from Copernicus ....Pages 179-189 Ultraviolet Si IV/C IV Ratios for Be Stars....Pages 191-195 The Near Ultraviolet Spectrum of ζ Tau....Pages 197-198 Spectroscopic Observations of the Be Stars η Cen, γ Cas and Φ Per....Pages 199-207 The Far Ultraviolet Spectra of υ Cyg and μ Cen....Pages 209-217 Photographic Infrared Spectroscopy and near Infrared Photometry of Be Stars....Pages 219-225 Paschen Decrements in Be Stars....Pages 227-227 The Classification of Faint Be Stars....Pages 229-231 Polarization in Be Stars....Pages 233-260 Polarization Measurements Across the Balmer Lines of Be and Shell Stars....Pages 261-275 Intrinsic Linear Polarization of Be Stars as a Function of υ sin i ....Pages 277-277 Front Matter....Pages 279-279 Line Formation in Expanding Atmospheres....Pages 281-312 Radiative Transfer in Dynamic Stellar Atmospheres....Pages 313-313 Si II Lines in the Shell of ζ Tau....Pages 315-320 The Complex Structure of the Ca II H and K Lines in the Spectrum of the A0ep Star with Infrared Excess HD 190073....Pages 321-321 Theoretical Emission-Line Profiles Computed at Ondřejov....Pages 323-325 Motions in the Shells and Atmospheres of V923 Aql and EW Lac and Their Manifestation in the Spectrum....Pages 327-331 Front Matter....Pages 333-333 Models for the Circumstellar Envelopes of Be Stars....Pages 335-370 On the Possible Role of Magnetic Fields in the Dynamics of the Be Phenomenon....Pages 371-373 Theoretical Wavelength Dependence of Polarization in Early-Type Stars....Pages 375-376 The Possible Role of Radiative Acceleration in Supporting Extended Atmospheres in Be Stars....Pages 377-382 Front Matter....Pages 383-383 Duplicity of Be Stars as Seen from Ondřejov....Pages 385-400 On the Detection of Binary Be Stars....Pages 401-415 Evidence for the Existence of Mass-Exchange Binary Be Stars from Periodic Spectral Variations....Pages 417-428 Toward a Model for the Be Binary System Φ Per....Pages 429-437 Final Remarks on the Binary Hypothesis for the Be Stars....Pages 439-444 Front Matter....Pages 445-445 General Discussion....Pages 447-451 Concluding Remarks....Pages 453-455 Back Matter....Pages 457-465 Proceedings of IAU Symposium No. 70 (Merrill-McLaughlin Memorial Symposium) held at Bass River, Massachusetts, U.S.A., September 15-18, 1975