A pseudo-planar, periodic-box formalism for modelling the outer evolution 
of structure in spherically expanding stellar winds

Runacres, Mark; Owocki, S. P.

doi:10.1051/0004-6361:20041281

Cited by 45 publications

(56 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…A recent study by Puls et al (2006) shows that, for O star supergiants with Hα in emission,Ṁ(radio) ≈ 0.4−0.5Ṁ(Hα). This is believed to be caused by a radial decrease in the amount of clumping, as is also predicted theoretically (Runacres & Owocki 2005). We find for Cyg OB2 No.…”

Section: Mass-loss Ratesupporting

confidence: 87%

Non-thermal radio emission from O-type stars

Blomme¹,

Becker

Volpi

et al. 2008

A&A

Self Cite

View full text Add to dashboard Cite

The star Cyg OB2 No. 9 is a well-known non-thermal radio emitter. Recent theoretical work suggests that all such O-stars should be in a binary or a multiple system. However, there is no spectroscopic evidence of a binary component. Re-analysis of radio observations from the VLA of this system over 25 years has revealed that the non-thermal emission varies with a period of 2.35 ± 0.02 yr. This is interpreted as a strong suggestion of a binary system, with the non-thermal emission arising in a wind-collision region. We derived some preliminary orbital parameters for this putative binary and revised the mass-loss rate of the primary star downward from previous estimates.

show abstract

Section: Mass-loss Ratesupporting

confidence: 87%

Non-thermal radio emission from O-type stars

Blomme¹,

Becker

Volpi

et al. 2008

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…Such large averages depend on results indicating that the outermost wind (beyond 1000 R * ) is also considerably clumped; cf. Runacres & Owocki (2005). Only for rather low values of κ max is a smooth radio regime predicted.…”

Section: Implications and Conclusionmentioning

confidence: 93%

Bright OB stars in the Galaxy

Puls¹,

Маркова²,

Scuderi³

et al. 2006

A&A

291

391

View full text Add to dashboard Cite

Context. Recent results strongly challenge the canonical picture of massive star winds: various evidence indicates that currently accepted mass-loss rates,Ṁ, may need to be revised downwards, by factors extending to one magnitude or even more. This is because the most commonly used mass-loss diagnostics are affected by "clumping" (small-scale density inhomogeneities), influencing our interpretation of observed spectra and fluxes. Aims. Such downward revisions would have dramatic consequences for the evolution of, and feedback from, massive stars, and thus robust determinations of the clumping properties and mass-loss rates are urgently needed. We present a first attempt concerning this objective, by means of constraining the radial stratification of the so-called clumping factor. Methods. To this end, we have analyzed a sample of 19 Galactic O-type supergiants/giants, by combining our own and archival data for H α , IR, mm and radio fluxes, and using approximate methods, calibrated to more sophisticated models. Clumping has been included into our analysis in the "conventional" way, by assuming the inter-clump matter to be void. Because (almost) all our diagnostics depends on the square of density, we cannot derive absolute clumping factors, but only factors normalized to a certain minimum. Results. This minimum was usually found to be located in the outermost, radio-emitting region, i.e., the radio mass-loss rates are the lowest ones, compared toṀ derived from H α and the IR. The radio rates agree well with those predicted by theory, but are only upper limits, due to unknown clumping in the outer wind. H α turned out to be a useful tool to derive the clumping properties inside r < 3. . .5 R . Our most important result concerns a (physical) difference between denser and thinner winds: for denser winds, the innermost region is more strongly clumped than the outermost one (with a normalized clumping factor of 4.1 ± 1.4), whereas thinner winds have similar clumping properties in the inner and outer regions. Conclusions. Our findings are compared with theoretical predictions, and the implications are discussed in detail, by assuming different scenarios regarding the still unknown clumping properties of the outer wind.

show abstract

“…The flares therefore roughly reach the luminosities expected on average for smooth winds but the minimal luminosities are much too low (Romano et al, 2014b), suggesting a mechanism quenching accretion most of the time rather than generating inhomogeneities. The wind clump scenario (Walter and Zurita Heras, 2007b) can perhaps explain density ratios up to 10 3−5 (Runacres and Owocki, 2005) between the clump and interclump medium. Such density contrasts are, however, predicted relatively far from the surface (∼ 10R * ) of the companion and low and large densities are expected i.e.…”

Section: Take the Rough With The Smoothmentioning

confidence: 98%

High-mass X-ray binaries in the Milky Way

Walter

Lutovinov

Bozzo

et al. 2015

Astron Astrophys Rev

234

View full text Add to dashboard Cite

High-mass X-ray binaries are fundamental in the study of stellar evolution, nucleosynthesis, structure and evolution of galaxies and accretion processes. Hard X-rays observations by INTEGRAL and Swift have broadened significantly our understanding in particular for the super-giant systems in the Milky Way, which number has increased by almost a factor of three. INTEGRAL played a crucial role in the discovery, study and understanding of heavily obscured systems and of fast X-ray transients. Most super-giant systems can now be classified in three categories: classical/obscured, eccentric and fast transient.The classical systems feature low eccentricity and variability factor of ∼ 10 3 , mostly driven by hydrodynamic phenomena occurring on scales larger than the accretion radius. Among them, systems with short orbital periods and close to Roche-Lobe overflow or with slow winds, appear highly obscured. In eccentric systems, the variability amplitude can reach even higher factors, because of the contrast of the wind density along the orbit. Four super-giant systems, featuring fast outbursts, very short orbital periods and anomalously low accretion rates, are not yet understood.Simulations of the accretion processes on relatively large scales have progressed and reproduce parts of the observations. The combined effects of wind

show abstract

A pseudo-planar, periodic-box formalism for modelling the outer evolution of structure in spherically expanding stellar winds

Cited by 45 publications

References 20 publications

Non-thermal radio emission from O-type stars

Non-thermal radio emission from O-type stars

Bright OB stars in the Galaxy

High-mass X-ray binaries in the Milky Way

Contact Info

Product

Resources

About