The initial mass function for massive stars in the Galaxy and the Magellanic Clouds

Humphreys, R. M.; McElroy, D. B.

doi:10.1086/162439

Cited by 356 publications

(353 citation statements)

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“…These settings are as follows: i) From 4110 to 4310 Å (covering Si II λλ4128, 4131 , Si IV λ4116 and He II λ4200). Humphreys (1978); b Garmany & Stencel (1992); c Barlow & Cohen (1977); d Denizman & Hack (1988); * from calibrations (Humphreys & McElroy 1984).…”

Section: Observations and Data Reductionmentioning

confidence: 99%

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Bright OB stars in the Galaxy

Маркова¹,

Puls²

2007

A&A

189

264

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Context. B-type supergiants represent an important phase in the evolution of massive stars. Reliable estimates of their stellar and wind parameters, however, are scarce, especially at mid and late spectral subtypes. Aims. We apply the NLTE atmosphere code FASTWIND to perform a spectroscopic study of a small sample of Galactic B-supergiants from B0 to B9. By means of the resulting data and incorporating additional datasets from alternative studies, we investigate the properties of OB-supergiants and compare our findings with theoretical predictions. Methods. Stellar and wind parameters of our sample stars are determined by line profile fitting, based on synthetic profiles, a Fourier technique to investigate the individual contributions of stellar rotation and "macro-turbulence" and an adequate approach to determine the Si abundances in parallel with micro-turbulent velocities. Results. Due to the combined effects of line-and wind-blanketing, the temperature scale of Galactic B-supergiants needs to be revised downward, by 10 to 20%, the latter value being appropriate for stronger winds. Compared to theoretical predictions, the wind properties of OB-supergiants indicate a number of discrepancies. In fair accordance with recent results, our sample indicates a gradual decrease in v ∞ over the bi-stability region, where the limits of this region are located at lower T eff than those predicted. Introducing a distance-independent quantity Q related to wind-strength, we show that this quantity is a well defined, monotonically increasing function of T eff outside this region. Inside and from hot to cool,Ṁ changes by a factor (in between 0.4 and 2.5) which is much smaller than the predicted factor of 5. Conclusions. The decrease in v ∞ over the bi-stability region is not over-compensated by an increase ofṀ , as frequently argued, provided that wind-clumping properties on both sides of this region do not differ substantially.

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Section: Observations and Data Reductionmentioning

confidence: 99%

“…For the two stars which do not belong to any cluster/association (HD 185859 and HD 212593), absolute magnitudes according to the calibration by Humphreys & McElroy (1984) have been adopted.…”

Section: Sample Starsmentioning

confidence: 99%

Bright OB stars in the Galaxy

Маркова¹,

Puls²

2007

A&A

189

264

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“…Also the LMC and the SMC show a deficiency of RSGs with M bol ≤ −9.5 (Humphreys & McElroy 1984) so that the single star and binary evolutionary scenario outlined above may apply in low metallicity regions as well. Notice that this "LBV scenario" was introduced more than a decade ago (Vanbeveren 1991), and we used it in all our PNS calculations since 1997.…”

Section: Stellar Wind Mass Loss Rate Formalisms In Massive Starsmentioning

confidence: 99%

The effects of binaries on the evolution of Wolf-Rayet type spectral features in starbursts

Bever

Vanbeveren

2003

A&A

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Abstract. In the present paper we investigate in detail the effects of binaries with initial period between 1 day and 10 years on theoretical simulations of Wolf-Rayet (WR) type spectral features in starbursts. We focus on the evolution of the nebular H β line in starburst in general, on the intensity ratios I(nebular He II λ4686)/I(H β ), I(blue bump)/I(H β ), and I(red bump)/I(H β ) as a function of the equivalent width of H β of WR galaxies in particular. The binary evolutionary processes that dominate the evolution of the considered spectral features are the Roche lobe overflow in case Br systems, the mass transfer efficiency, and the merger rate. We show that the predictions on nebular He II depend critically on the uncertainties in the theory of WR atmospheres and particularly on uncertainties in the treatment of the subsonic velocity region of the WR wind. The observations of low metallicity starbursts are best reproduced by a theoretical model with a significant number of binaries and with a metallicity-dependent WR wind.

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“…The kinematical data were adopted from the catalogue by Mel'nik & Dambis (2009). The ages of OB-associations are supposed to be less than 30 Myr (Humphreys & McElroy 1984;Bressan et al 2012).…”

Section: Catalogues and Modelsmentioning

confidence: 99%