Mass Loss and Evolution of O-Type Stars

The organization of this Symposium had its beginnings at the International Astronomical Union General Assembly in Grenoble in 1976. The initial "rounding up" of the Scienti­ fic Organizing Committee was begun by Drs. Snow and Swings; most of us who became the eventual organizing committee met a few times during the Assembly and formulated the essential outlines of the meeting. Extensive correspondence with all the committee subsequently established the program. The idea was to bring together both observers and theoreticians to discuss the stellar winds and mass loss rates and their effects on evolutions of O-type stars. On the observational side, there are now spectroscopic data from the far UV to the near IR regions concerning the stellar winds. There is also information about the free-free emission in the wind from the IR and radio portions of the spectrum. Fortunately, these different detection methods give more or less the same mass loss rate for the one star, s Pup" which has been observed at all wavelengths. One of the intents of the first three sessions of this Symposium is to outline the eXisting data on mass loss rates as it per­ tains to the O-type stars.

Session 1 - Optical Spectroscopy.- The O stars-optical review (Invited Lectune)..- H alpha variations in two mass losing stars..- Short term variability of line strengths in some Of and Wolf-Rayet stars..- Mass loss in the spectrum of the 06.5f binary HD 153919..- Mass loss of B1 la-O super-giants and evolutionary consequences..- On the formation of the continuous spectrum and emission line profiles of P Cygni..- Evidence for non-isotropic mass loss from central stars of some emission nebulae..- Mass loss from Eta Carinae.- Wolf-Rayet stars in the Magellanic Clouds..- Stellar outflow: relative motions of nebulae and Of stars..- Session 2 - Ultraviolet Spectroscopy.- An ultraviolet view of stellar winds (Invited lectune).- Modelling of UV resonance lines..- O VI in stellar winds..- C IV resonance line profiles in O stars..- Winds in hot, subluminous stars..- Temperatures and radii of O stars..- Analysis of UV spectrophotometric observations for O-type stars..- The effective temperatures of the O stars..- Session 3 - Infrared and Radio Data.- Radio and infrared emission by O-type and related stars (Invited Lectune)..- Near infrared spectra of O stars and related objects..- Infrared observations of HDE 226868/Cyg ?-1 and HDE 245770/A 0535+26..- Infrared excesses and mass loss: Implications for OB stars in Carina and the LMC..- Radio emission from flows..- Radio observations of stellar mass loss.- Radio emission from hot stars at two centimeters..- Session 4 - Panel Discussion on Stellar Wind Theories.- The theory of mass loss from hot stars (Introductory paper)..- Radiatively-driven winds: Model improvements, ionization balance and the infrared spectrum..- The warm wind model..- The corona plus cool wind model for Of stars and OB supergiants..- The thermodynamicrequirements on atmospheric models imposed by observed stellar nonthermal mass fluxes and by those observed nonthermal features enhanced in Xe stars..- Session 5 - Theory and Mass Loss Rates - Binary Stars - Miscellaneous Topics.- The domain of radiatively driven mass loss in the HR diagram..- Stellar corona models..- Synthetic line profiles in early-type stellar winds. I. H and He+..- The H? profile in Zeta Puppis..- The mass loss rate of ? Velorum..- Wind models for ? Orionis.- Binary frequency among the O-type stars..- Contact binaries of spectral type O..- The O-type spectroscopic binary system HD 149404..- The O-type spectroscopic binary system HD 93206..- Mass flow and evolution of UW Canis Majoris..- The spectroscopic binary ?2 Velorum..- The binary orbit of HD 92740..- Results from the 1977 coordinated observing campaign on HD 226868=Cygnus X-1..- The nature of the runaways: old disk population OB stars?.- The distribution in luminosity of OB stars and evolutionary time scales..- H-deficiency and mass loss..- Session 6 - Evolution with Mass Loss: Single Stars.- Evolution of single stars with mass loss (Invited Lectune)..- Theoretical evolution of massive stars with mass loss by stellar wind..- Critical rates of mass loss..- Supergiant mass loss and the Cassiopeia A progenitor..- The role of rotation in the evolution of massive stars losing mass..- Evolution of a 30 Mo star with mass loss..- Mass conservation and rapid mass loss on the main sequence..- Session 7 - Evolution with Mass Loss: Double Stars.- Evolution of binary stars with mass loss (Invited Lecture)..- Evolution of massive common envelope binaries and mass loss..- The influence of stellar wind mass loss on the evolution of massive close binaries..- Common envelope binaries and mass loss..-HD 50896: an other WR binary star..- Session 8 - Evolutionary Scenario and the wr Connection.- Evolution of O stars and the WR connection (Invited Lectune)..- The galactic WN7/WN8 stars as massive O stars in advanced stages of evolution..- The chemical nature and evolutionary status of the Wolf-Rayet stars..- Of-WN evolution: spectral types and effective temperatures..- Observations of velocity fields in WN and Of stars..- BE 381: WN9 or 08 Iafpe?.- Conservative and non-conservative evolutionary computations in connection with Wolf-Rayet binaries..- Summary of the conference Projects for future research..