Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars

Underhill, Anne B.; Divan, L.; Prevot-Burnichon, M. L.; Doazan, V.

doi:10.1093/mnras/189.3.601

Cited by 89 publications

(30 citation statements)

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“…These have resulted, however, in different values being derived, mainly because of the influence of the circumstellar envelope. The following parameter ranges have been reported in the literature: T eff ¼ 22;500-30,000 K, log g ¼ 3:3-4.0, M V ¼ À3:00 to À3.83 mag, and A V ¼ 0:25-0.69 mag (Nordh & Olofsson 1974;Underhill et al 1979;Snow 1981;Goraya 1985;Theodossiou 1985;Kaiser 1989;Fabregat & Reglero 1990;Zorec & Briot 1991).…”

Section: Introductionmentioning

confidence: 97%

A Study of π Aquarii during a Quasi‐normal Star Phase: Refined Fundamental Parameters and Evidence for Binarity

Bjorkman

Мирошниченко

McDavid

et al. 2002

ApJ

135

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We present the results of recent multicolor photometric and high-resolution spectroscopic observations of the bright Be star Aqr. Observational data collected from the literature were used to study the star's variations over the last four decades. The star is identified with the IR sources F22227+0107 in the IRAS Faint Point Source Catalog and MSX5 G066.0066À44.7392 in the MSX Catalog. The variations in near-IR brightness of Aqr are found to be among the largest reported for Be stars. Since 1996, the star has shown only weak signs of circumstellar emission, which has allowed us to refine the fundamental stellar parameters: A V ¼ 0:15 mag, T eff ¼ 24;000 K, log g ¼ 3:9, and M V ¼ À2:95 mag. A weak emission component of the H line has been detected during the recent quasi-normal star phase. From analysis of the H line profiles, we find antiphased radial velocity variations of the emission component and the photospheric absorption, with a period of 84.1 days and semiamplitudes of 101.4 and 16.7 km s À1 , respectively. This result suggests that Aqr may be a binary system consisting of stars with masses of M 1 sin 3 i ¼ 12:4 M , M 2 sin 3 i ¼ 2:0 M . We also estimate the orbital inclination angle to be between 50 and 75 . We suggest that the photometric, spectroscopic, and polarimetric variations observed during the second half of the 20th century may be due to variable mass transfer between the binary components.

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Section: Introductionmentioning

confidence: 97%

A Study of π Aquarii during a Quasi‐normal Star Phase: Refined Fundamental Parameters and Evidence for Binarity

Bjorkman

Мирошниченко

McDavid

et al. 2002

ApJ

135

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“…However doubts exist on the high effective temperatures of O-stars. Underhill et al (1979) suggest that the effective temperatures for early O-stars can be smaller than given by the scale of Conti (1973) derived from helium lines; the latter could reflect the presence of a heated transition zone between the photosphere and a corona, rather than the integrated flux from the stars. …”

Section: Opacitiesmentioning

confidence: 88%

“…Only for a small number of O-stars empirical effective temperatures are derived (Underhill et al, 1979;Conti, 1973). Using the UV flux distribution given by $2/68 over the range 1380 to 11 084 ~, completed by flux estimates from model atmospheres, and angular diameters Underhill et al derived an effective temperature scale for stars of types 08 and later.…”

Section: Temperatures and Luminosities Of O-starsmentioning

confidence: 99%

The evolution of massive stars

Loore

1980

Space Sci Rev

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The evolution of stars with masses between 15M0 and 100M0 is considered. Stars in this mass range lose a considerable fraction of their matter during their evolution.The treatment of convection, semi-convection and the influence of mass loss by stellar winds at different evolutionary phases are analysed as well as the adopted opacities.Evolutionary sequences computed by various groups are examined and compared with observations, and the advanced evolution of a 15Mo and a 25M0 star from zero-age main sequence (ZAMS) through iron collapse is discussed.The effect of centrifugal forces on stellar wind mass loss and the influence of rotation on eyolutionary models is examined. As a consequence of the outflow of matter deeper layers show up and when the mass loss rates are large enough layers with changed composition, due to interior nuclear reactions, appear on the surface.The evolution of massive close binaries as well during the phase of mass loss by stellar wind as during the mass exchange and mass loss phase due to Roche lobe overflow is treated in detail, and the value of the parameters governing mass and angular momentum losses are discussed.The problem of the Wolf-Rayet stars, their origin and the pq~sibilities of their' production either as single stars or as massi:ce binaries is examined.Finally, the origin of X-ray binaries is discussed and the scenario for the formation of these objects (starting from massive ZAMS close binaries, through Wolf-Rayet binaries leading to OB-stars with a compact companion after a supernova explosion) is reviewed and completed, including stellar wind mass loss.

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“…A number of recent studies have contributed to a significantly increased accuracy in effective-temperature determinations. Among these studies are the lunar-occultation measurements of red giants by Ridgway and collaborators (see Schmidtke et al 1986, and references given there), the systematic application of the infrared-flux method of Blackwell and Shallis (1977) to different types of stars (early-type stars : Underhill et al 1979, Underhill 1982, Remie and Lamers 1982solar-type dwarfs: Saxner andHammarbäck 1985, Magain 1987;G-K giants: Bell and Gustafsson 1987;M and C giants: Tsuji 1981 a and b), the use of line spectra and ionization equilibria, supported by non-LTE calculations for O-stars by Kudritzki and collaborators (e.g. Kudritzki et al 1983) and the use of Balmer-line profiles for solar-type stars by Cayrel et al (1985) .…”

Section: Fundamental Parametersmentioning

confidence: 99%

Physical Input for the Determination of Stellar Abundances

Gustafsson

1988

Symp. - Int. Astron. Union

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ABSTRACT.The fundamental parameters and the physical modelling and data used in the analysis of high-resolution high S/N spectra of stars are discussed. Particular emphasis is led on recent developments in these respects and the importance of further improvements is stressed. INTRODUCTIONFor weak stellar spectral line the equivalent width is approximately proportional to the chemical abundance of the element in question and the oscillator strength. The factor of proportionality is, however, dependent on stellar parameters, atmospheric structure and other data and processes that directly affect the line formation. The equivalent widths can today, in high S/N spectroscopy at sufficient resolution, be measured with an accuracy of 10% or better. The f values can in many cases be determined with an even higher accuracy (cf. Huber's review in the present volume). Thus, one could hope that abundances could be estimeted with a corresponding accuracy. This is, in general, not possible; typical external errors in abundances are in good cases about 30%, and often greater than that. The reason for this is our lack of precise knowledge about the fundamental parameters, atmospheric structures and line formation. A clear-cut separation between the errors in chemical abundances caused by uncertainties in these different respects is rather artificial. In particular, the approximation of the atmospheric structures by a grid of standard model atmospheres also affects the choice of fundamental parameters (if made spectroscopically or photometrically * Present address:

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Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars

Cited by 89 publications

References 0 publications

A Study of π Aquarii during a Quasi‐normal Star Phase: Refined Fundamental Parameters and Evidence for Binarity

A Study of π Aquarii during a Quasi‐normal Star Phase: Refined Fundamental Parameters and Evidence for Binarity

The evolution of massive stars

Physical Input for the Determination of Stellar Abundances

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