Wolf-Rayet Stars: Observations, Physics, Evolution

ISBN-13: 9789027714701 / Angielski / Miękka / 1982 / 636 str.

C. de Loore; A. J. Willis; C. Loore

Opis

The formative ideas for this symposium originated in 1978 at the IAU Symposium No. 83 on "Mass Loss and Evolution of O-type Stars" held at Qualicum Beach, Vancouver Island, Canada - WR stars generally figure prominently in O-star meetings and vice versa Following general appro val by the IAU Executive Committee the initial ideas were cemented at a subsequent meeting, IAU Colloquium No. 59 on "The Effects of Mass Loss on Stellar Evolution," held at Miramare, Trieste, Italy in 1980, which was attended by the ma, jority of the present Scientific Organising Committee and at which meeting the outline programme for this symposium was formulated. 1981 was considered an appropriate year in which to hold a meeting on WR stars, since the last IAU Symposium devoted to this stellar class had been held a decade earlier, in Buenos Aires (IAU Sym posium No. 49), and during this intervening period a wealth of new observational material had been obtained for WR stars together with significant advances on the theoretical front. The venue for this sym posium was chosen from the requirement, which can be inferred from the above, that a meeting on 'hot' stars take place in an appropriate, sunny climate and followed upon the excellent suggestion of Dr. C. Firmani to hold the symposium in Mexico."

Spis treści

Session 1 — The Wolf-Rayet Phenomenon.- Wolf-Rayet phenomena (Invited lecture).- The effective temperatures of early WR stars.- The galactic distribution of WR stars.- Line strengths in WN stars.- Hot mantles, moderate photospheres for WR stars.- Corrections for hydrostatic atmospheric models: radii and effective temperatures of WR stars..- Preliminary results of a new study of the intrinsic properties of WR stars.- Radio observations of HD 193793.- Near-infrared photometry of southern galactic WR stars..- Infrared (1.4–4.1?m) spectra of WR stars.- The infrared recombination-line spectra of WR stars.- Session 2 — The Chemistry of the Wolf-Rayet Stars.- The chemical composition of the WR stars (Invited lecture).- Chemical composition of WR stars: Abundant evidence for anomalies.- H/He ratios for WN stars in the LMC and the Galaxy.- The C/N ratio in WN and WC stars.- On the chemical abundances, evolutionary stage and bolometric magnitude of WR stars.- Absolute spectrophotometry of WR stars: are the colors the same?.- An explanation of the radio flux mystery of HD 192163 and empirical models for WN stars.- Carbon abundance in WC stars.- Synthetic spectra for WN stars.- Carbon abundance in the WC 11 star CPD -56°8032.- Session 3 — Mass Loss from WR Stars: Observations & Theory.- Observations of mass loss from OB and WR stars (Invited lecture).- Theories for the winds from WR stars (Invited lecture).- The theory of radiation driven stellar winds and the WR phenomenon (Invited lecture).- The influence of the ratio of total to selective extinction on the determination of the mass loss rate of WR stars from IR excess measurements.- On the properties of the WR stars and their mass loss.- A hot corona model for O-stars and WR stars..- Radio continuum measurements of mass loss from WR stars.- Radio emission from WR stars.- Infrared spectroscopy of WN stars.- The near-IR properties of selected WN stars in the Large Magellanic Cloud.- Near IR observations of galactic WN stars.- Line formation in winds with enhanced equatorial mass loss rates and its application to the WR star HD 50896.- Session 4 — Observations of Wolf-Rayet Binaries.- WR stars with massive companions (Invited lecture).- WR stars with compact companions (Invited lecture).- The iron curtain of WC9 stars.- A spectroscopic search for duplicity among a complete sample of northern galactic WR stars.- Is HD 164270 a long-period eclipsing binary?.- A spectral study of HD 50896.- Observations of new WR binaries.- The velocity field of S 308. the ring nebula around the WN5 star HD 50896.- Spectral variations of Theta Muscae (WC6+09.5I) in the ultraviolet.- The WR eclipsing binary HD 5980 in the SMC.- Session 5 — Evolutionary Status of Wolf-Rayet Stars.- The evolution of massive stars: the production of “single” WR stars (Invited lecture).- The evolution of massive stars—the production of binary WR stars (Invited lecture).- Gradients in supergiant and WR stars across the galactic plane.- On the expected frequency of WR + compact star systems.- Properties of the scenario for the formation of WR stars as post-red supergiants.- Origin and evolution of Wolf-Rayet stars.- The massive eclipsing binary RY Scuti.- The WO Wolf-Rayet stars.- The ON stars: a wider spectroscopic definition.- On the structure and evolution of the OB-companions in Wolf-Rayet binaries.- The occurrence of different Wolf-Rayet phases in massive close binaries.- The various scenarios leading to WR stars: their relative importance and the role of mixing.- Session 6 — Low Mass Wolf-Rayet Stars Ring Nebulae.- Low mass Wolf-Rayet stars: theory.- Subluminous Wolf-Rayet stars: observations.- The peculiar binary system HD 45166 (Sd0+B8v?).- The UV spectrum of the central star of NGC 40.- A reclassification of WC and “0 VI” central stars of planetary nebulae and comparison with population I WC stars..- A new search for nebulae surrounding Wolf-Rayet stars.- Ring nebulae associated with Wolf-Rayet stars.- Ring nebulae around WC6 stars: NGC 6357 around HD 157504.- Kinematics of the ring-shaped nebula N206 in the LMC.- WR stars with ring nebulae.- IUE observations of the WN-C star HD 62910.- Session 7 — Wolf-Rayet Stars in External Galaxies.- Observations and the Wolf-Rayet evolutionary scenario (Invited lecture).- Wolf-Rayet stars in the Magellanic Clouds: spectroscopic binaries and masses (Invited lecture).- Absolute magnitudes of Wolf-Rayet stars: the WN3 and WN4 sub-classes in the LMC.- Near infrared observations of Magellanic WN stars.- The first detection of Wolf-Rayet stars in M31.- Wolf-Rayet stars in open clusters and associations.- The Wolf-Rayet stars in 30 Doradus.- Spectra of the Wolf-Rayet stars in 30 Doradus.- NGC 604: a giant H II region dominated by many WR stars.- Wolf-Rayet stars associated to giant regions of star formation.- The central object of the 30 Doradus nebula, a supermassive star.- Session 8 — X-Ray Data — Miscellaneous Topics — General Discussion.- Wolf-Rayet stars in emission-line galaxies.- Comments on the significance of the positions of population I Wolf-Rayet stars in the HR diagram.- Time-dependent X-ray observations of Wolf-Rayet binaries with O-type and with suspected compact companions.- Lines profile variations and binarity in Wolf-Rayet stars.- X-rays from Wolf-Rayet stars observed by the Einstein observatory.- Summary of symposium.- Open discussion.