Theoretical continuum energy distributions for Wolf-Rayet stars

Schmutz, W.; Leitherer, Claus; Gruenwald, R.

doi:10.1086/133104

Cited by 142 publications

(191 citation statements)

References 15 publications

(24 reference statements)

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“…For stars with parameters beyond the range of these models we use Kurucz (1992) atmospheres. For comparison with Starburst99 we include an option of using the models of (Smith et al 2005) for both WR and OB stars (atmosSmith), and for comparison with earlier studies an alternative set of models (atmosOLD) consisting of the WR models of Schmutz et al (1992) and the OB models of Schaerer & de Koter (1997), again supplemented by the models of Kurucz (1992).…”

Section: Ionizing Fluxmentioning

confidence: 99%

“…The lifetime of 60 Fe has recently been revised to ∼3.8 Myr, from the previous estimate of ∼2 Myr (Rugel, private communication). While the lines are significantly weaker than Article published by EDP Sciences Kurucz (1992); Schmutz et al (1992); Schaerer & de Koter (1997) the 26 Al line, it is possible to detect them when integrating over large regions of the Milky Way.…”

Section: Introductionmentioning

confidence: 99%

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Using population synthesis of massive stars to study the interstellar medium near OB associations

Voss

Diehl²,

Hartmann

et al. 2009

A&A

127

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Aims. We study the massive stars in OB associations and their surrounding interstellar medium environment, using a population synthesis code. Methods. We developed a new population synthesis code for groups of massive stars, where we model the emission of different forms of energy and matter from the stars of the association. In particular, the ejection of the two radioactive isotopes 26 Al and 60 Fe is followed, as well as the emission of hydrogen ionizing photons, and the kinetic energy of the stellar winds and supernova explosions. We investigate various alternative astrophysical inputs and the resulting output sensitivities, especially effects due to the inclusion of rotation in stellar models. As the aim of the code is the application to relatively small populations of massive stars, special care is taken to address their statistical properties. Our code incorporates both analytical statistical methods applicable to small populations, as well as extensive Monte Carlo simulations. Results. We find that the inclusion of rotation in the stellar models has a large impact on the interactions between OB associations and their surrounding interstellar medium. The emission of 26 Al in the stellar winds is strongly enhanced, compared to non-rotating models with the same mass-loss prescription. This compensates the recent reductions in the estimates of mass-loss rates of massive stars due to the effects of clumping. Despite the lower mass-loss rates, the power of the winds is actually enhanced for rotating stellar models. The supernova power (kinetic energy of their ejecta) is decreased due to longer lifetimes of rotating stars, and therefore the wind power dominates over supernova power for the first 6 Myr after a burst of star-formation. For populations typical of nearby star-forming regions, the statistical uncertainties are large and clearly non-Gaussian.

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Section: Ionizing Fluxmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Using population synthesis of massive stars to study the interstellar medium near OB associations

Voss

Diehl²,

Hartmann

et al. 2009

A&A

127

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“…A possible explanation for nebular HeII emission in metaldeficient objects is that in such low metallicity environments, WR stars possess sufficiently weak winds that are optically thin in the He + continuum (e.g., Schmutz et al 1992), thereby allowing the He + -ionizing radiation to escape from the stellar atmospheres. Thus, empirical determination of the stellar parameter space associated with nebular HeII photoionization will provide much-needed constraints for WR model atmospheres (e.g., Schaerer 1996;Crowther et al 1999;Schaerer 2002).…”

Section: Introductionmentioning

confidence: 99%

Gemini GMOS spectroscopy of HeII nebulae in M 33

Kehrig

Oey

Crowther

et al. 2011

A&A

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We have carried out a narrow-band survey of the Local Group galaxy, M 33, in the HeII λ4686 emission line, to identify HeII nebulae in this galaxy. With spectroscopic follow-up observations, we confirm three of seven candidate objects, including identification of two new HeII nebulae, BCLMP651, HBW673. We also obtain spectra of associated ionizing stars for all the HII regions, identifying two new WN stars. We demonstrate that the ionizing source for the known HeII nebula, MA 1, is consistent with being the earlytype WN star MC8 (M 33-WR14), by carrying out a combined stellar and nebular analysis of MC8 and MA 1. We were unable to identify the helium ionizing sources for HBW 673 and BCLMP 651, which do not appear to be Wolf-Rayet stars. According to the [OIII]λ5007/Hβ vs.[NII]λ6584/Hα diagnostic diagram, excitation mechanisms apart from hot stellar continuum are needed to account for the nebular emission in HBW 673, which appears to have no stellar source at all.

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“…WR stars also compare closely with comparable temperature O stars in their ionizing flux per unit area. Schmutz et al (1992) stress the importance of stellar wind density on the ionizing flux distributions of WR stars, such that emission at λ ≤228Å relies on the WR wind being relatively transparent. Denser winds, such as those presented above for representative Galactic WR stars, destroy photons beyond this edge.…”

Section: The Effect Of Blanketing On Ionizing Fluxesmentioning

confidence: 89%

Progress in model atmosphere studies of Wolf-Rayet stars

Crowther

1999

Symp. - Int. Astron. Union

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Abstract. Recent progress in the quantitative analysis of Wolf-Rayet stars is reviewed, emphasising the role played by choice of spectral diagnostics, clumping and line blanketing on derived stellar properties. The ionizing properties of WR stars are discussed, based on clumped, line blanketed models for WN and WC stars. The role of metallicity and mass-loss is assessed, and the role of H ii regions as probes of predicted Lyman continuum distributions. Suggestions are made for differences in observed properties of WCE and WO subtypes.

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Theoretical continuum energy distributions for Wolf-Rayet stars

Cited by 142 publications

References 15 publications

Using population synthesis of massive stars to study the interstellar medium near OB associations

Using population synthesis of massive stars to study the interstellar medium near OB associations

Gemini GMOS spectroscopy of HeII nebulae in M 33

Progress in model atmosphere studies of Wolf-Rayet stars

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