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  • Other Sources  (25)
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  • 1
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    The absolute magnitudes and spectral types of the stars in the gamma Velorum system. (1972)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The ratio of the visual luminosities of the O and WC components of the binary system gamma (2) Vel has been derived by comparison of the emission-line strengths in the spectrum with those in the spectrum of a single WC8 star, HD 192103. The result is 1.4 mag, with the O star being brighter; the classification of the O star was found to be 09 I, so that the classification of gamma (2) Vel is WC8+09 I.
    Keywords: SPACE SCIENCES
    Type: Astrophysical Journal; 172; Mar. 15
    Format: text
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  • 2
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    The Sixth Catalogue of galactic Wolf-Rayet stars, their past and present (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: This paper presents the Sixth Catalogue of galactic Wolf-Rayet stars (Pop. I), a short history on the five earlier WR catalogues, improved spectral classification, finding charts, a discussion on related objects, and a review of the current status of Wolf-Rayet star research. The appendix presents a bibliography on most of the Wolf-Rayet literature published since 1867.
    Keywords: ASTRONOMY
    Type: Space Science Reviews; 28; 3, 19; 1981
    Format: text
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  • 3
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    Spectroscopic observations of selected stellar systems (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Spectra of very luminous, high temperature stars, the o-type stars with the largest masses among stars, and the Wolf-Rayet (W-R) stars are studied. These stars are characterized by strong stellar winds which produce signiicant mass loss. The nature and evolution of these winds are studied to learn the densities, velocity structue, ionization balance, and composition. The IUE satellite provides the best way to study these phenomena because many of the most important ground state and excited state lines of common highly ionized species are found in the spectral range.
    Keywords: ASTROPHYSICS
    Type: NASA-CR-174288 , NAS 1.26:174288
    Format: application/pdf
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  • 4
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    Surface composition changes in massive star evolution with mass loss (1980)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A series of evolutionary models of 40-100 solar mass objects undergoing mass loss are constructed with the explicit inclusion of the surface composition of H, He, C, N, O elements. Mass loss rates similar to those observed in Of stars, 4 to 7 x 10 to the -6th solar masses/yr, result in an appearance at the surface of equilibrium CNO products, i.e. enhanced nitrogen and diminished carbon, while that star is still burning hydrogen in the core. This result obtains because the initial convection core is a relatively large fraction of the total mass and rather modest loss exposes levels of anomalous composition. It is suggested that these objects might reasonably be identified as those luminous late type WN stars still containing surface hydrogen.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 92; 3, De; Dec. 198
    Format: text
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  • 5
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    IUE observations of eight OB stars in NGC 2244 - Ultraviolet continua and extinction (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Low-resolution IUE ultraviolet continuum observations of O and B stars in the young open cluster NGC 2244 are presented. When only relative energy distributions are considered, thereby eliminating any dependence on reddening corrections or absolute energy calibrations, it is found that the ultraviolet energy distributions of the O stars have significantly cooler ultraviolet color temperatures than the cluster early B stars. The effect is not considered a property of the B stars because their observed continua can be well represented by model atmospheres and ultraviolet extinction characteristic of the local interstellar medium. The effect is thus thought to originate with the O star continua and can be due to either interstellar effects (the cluster O stars suffer additional extinction which has an anomalous wavelength dependence) or stellar effects (the physics incorporated into current O star model atmospheres is inadequate). It is noted that current data do not allow a definitive distinction to be made between these two alternatives, and the possible origins and consequences of each are considered.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 248
    Format: text
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  • 6
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    Mass-loss rates from early-type stars (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The mass loss rates are derived for a number of unevolved O-type stars and a few WN stars from high dispersion IUE spectra of their P Cygni profiles. When combined with other published mass loss rates, it is found that the relationship between log m and M sub BOL is a broad band rather than a linear relation, suggesting that the line radiation driven wind theory may not be sufficient to explain mass loss. The mass loss rates for the WN stars, while more uncertain, confirm that these stars lose mass about 100 times faster than O-stars.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Universe at Ultraviolet Wavelengths: The First Two Yrs. of Intern. Ultraviolet Explorer; p 115-120
    Format: application/pdf
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  • 7
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    Mass loss from O-type stars (1980)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: We determine mass loss rates for six O-type stars from the violet-shifted absorption profile of the resonance C IV and N V lines, using the IUE satellite and the high-resolution camera. The values are substantially below those of Of stars (which have optical emission lines) of similar luminosity.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
    Format: text
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  • 8
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    Stellar winds from hot stars in the Magellanic Clouds (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: O and B stars in the LMC and SMC have been observed with the IUE in order to compare their winds and mass loss rates with those of their galactic counterparts. It is found that while the wind terminal velocities are generally about 20 percent lower than in galactic stars of the same spectral type, it is not clear that the mass loss rates are significantly lower. This conclusion differs from the conclusions of other studies, and the reasons are discussed. The most important reason is that a less luminous set of stars with new spectral types determined from slit spectra is being examined. The discussion of stellar winds rests heavily on a comparison of relevant wind parameters observed in O stars using both high and low dispersion IUE spectra.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 293; 407-413
    Format: text
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  • 9
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    Mass loss in O-type stars - Parameters which affect it (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Newly determined mass loss rates are presented for sixteen O-type stars in three open clusters. Combining the data with that already in the literature, no evidence is found that the rates are different in clusters with differing galactocentric distances and compositions, at least near the sun. There is still appreciable dispersion in the relationship between the mass loss rate and the stellar luminosity. It may be that the mass loss depends additionally on the stellar mass and/or radius, but these data cannot unequivocally indicate which physical dependence is correct. Evidence is found that a stellar wind increases as a massive star evolves from the zero-age main sequence.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 284; 705-711
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  • 10
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    Variable outflow in the O6ef star Lambda Cephei (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The paper analyzes spectroscopic data from the UV region using the Copernicus satellite on six consecutive days in September, 1975. It is found that the P Cygni lines of C III at 1175 A and of N V at 1238 and 1242 A show little or no variation in their profiles. The results indicate that the changes in the 4686-A H II and H-alpha can be interpreted as a variable outflow near the surface of the star, either due to random density inhomogeneities propagating outward, or the effects of rotation of a nonspherical star, or both. Insufficient data exist at present to distinguish between periodic and random fluctuations.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 228
    Format: text
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