The ionization structure of early-B supergiant winds

Prinja, R. K.; Massa, Derck; Searle, S.C.

doi:10.1051/0004-6361:200400129

Cited by 25 publications

(34 citation statements)

References 17 publications

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“…There is considerable observational evidence that hot-star winds are clumped both on small and large length scales. The presence of structure significantly influences the mass-loss rate determinations ( Fullerton et al 2006;Prinja et al 2005;Puls et al 2006). This in turn is important for models of stellar and galactic evolution.…”

Section: Introductionmentioning

confidence: 99%

Modeling Ultraviolet Wind Line Variability in Massive Hot Stars

Lobel¹,

Blomme²

2008

ApJ

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We model the detailed time-evolution of discrete absorption components (DACs) observed in P Cygni profiles of the Si iv k1400 resonance doublet lines of the fast-rotating supergiant HD 64760 (B0.5 Ib). We adopt the common assumption that the DACs are caused by corotating interaction regions (CIRs) in the stellar wind. We perform 3D radiative transfer calculations with hydrodynamic models of the stellar wind that incorporate these large-scale density-and velocity-structures. We develop the 3D transfer code Wind3D to investigate the physical properties of CIRs with detailed fits to the DAC shape and morphology. We constrain the properties of large-scale wind structures with detailed fits to DACs observed in HD 64760. A model with two spots of unequal brightness and size on opposite sides of the equator-20% AE 5% and 8% AE 5% brighter than the stellar surface and with opening angles of 20 AE 5 and 30 AE 5 diameter, respectively-provides the best fit to the observed DACs. The recurrence time of the DACs compared to the estimated rotational period corresponds to spot velocities that are 5 times slower than the rotational velocity. The massloss rate of the structured-wind model for HD 64760 does not exceed the rate of the spherically symmetric smoothwind model by more than 1%. The fact that DACs are observed in a large number of hot stars constrains the clumping that can be present in their winds, as substantial amounts of clumping would tend to destroy the CIRs.

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Section: Introductionmentioning

confidence: 99%

Modeling Ultraviolet Wind Line Variability in Massive Hot Stars

Lobel¹,

Blomme²

2008

ApJ

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“…Prinja et al 2005) and Si 3+ may be expected to be dominant. However, the spectra of both stars have Si iiiλ1206 and C ivλλ1550 wind lines that are unsaturated at intermediate velocities and have saturated NACs.…”

Section: Discussionmentioning

confidence: 99%

“…The surveys cited above suggest that NACs may be present, at some time, in most OB stars with well developed but unsaturated wind lines. For example, a preliminary examination of the 106 B0-B5 supergiant sample analysed by Prinja et al (2005) indicates that NACs are evident in ∼70% of the stars which exhibit well-developed, unsaturated P Cygni profiles in either Siiv or Civ.…”

Section: Narrow Absorption Componentsmentioning

confidence: 99%

“…The sensitivity of these effects to stellar winds is especially important in view of recent developments which suggest that the mass loss rates of OB stars may be in question at the order-of-magnitude level, and not just a few % (e.g. Massa et al 2003;Repolust et al 2004;Bouret et al 2005;Prinja et al 2005;Fullerton et al 2006;Puls et al 2006;Cohen et al 2006). Investigations of clumping and structures in the stellar winds are pivotal in understanding how large discrepancies between different mass loss rate determinations can arise.…”

Section: Introductionmentioning

confidence: 99%

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Ultraviolet diagnostic of porosity-free mass-loss estimates in B stars

Prinja¹,

Massa²

2013

A&A

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Aims. We seek to establish evidence in UV P Cygni line profiles that the signs of wind clumping and porosity vary with velocity. We aim to demonstrate empirically that while at most wind velocities optically thick clumps cover only a fraction of the stellar surface, close to the terminal velocity (v ∞ ) where narrow absorption components (NACs) appear in UV lines the covering factor is approximately unity. Methods. SEI line-synthesis models are used to determine the radial optical depths (τ rad (w)) of blue and red components of the Siiv λλ1400 resonance line doublet in a sample of 12 B0 to B4 supergiants. We focus on stars with well developed NACs and relatively low v ∞ so that the Siiv doublet components can be treated as radiatively decoupled and formed independently. Results. For all 12 stars the mean optical depth ratio of the blue to red components is closer to ∼2 (i.e. the ratio of oscillator strengths) in the NACs than at intermediate and lower velocities. The product of mass-loss rate and ion fraction (Ṁ q(Si 3+ )) calculated from the NAC optical depths is a factor of ∼2 to 9 higher compared to mass-loss values sampled at ∼0.4 to 0.6 v ∞ . Conclusions. Since the wind effectively becomes "smooth" at the high NAC velocities and the column density is uniformly distributed over the stellar disk, the optical depths of the NACs are not seriously affected by porosity and this feature thus provides the most reliable measurement of mass-loss rate in the UV lines. Applications of this result to the weak-wind problem of late O-dwarf stars and the "P v mass loss discordance" in early O supergiants are discussed.

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“…Parameters of the calculated m-CAK models with δ 0 from Abbott (1982), terminal velocity, V ∞ (km s −1 ), the local mass loss rate, F m (10 −6 M yr −1 ) and r c /R * , the location of the critical point. Prinja et al (2005) investigated the ionization structure of early-B supergiant winds and demonstrated that the wind ionization increases with distance from the star. This structure is different to the one exhibited by an O-star wind.…”

Section: The Slow Solutionmentioning

confidence: 99%

Outflowing disk formation in B[e] supergiants due to rotation and bi-stability in radiation driven winds

Curé¹,

Rial²,

Cidale³

2005

A&A

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Abstract. The effects of rapid rotation and bi-stability upon the density contrast between the equatorial and polar directions of a B[e] supergiant are re-investigated. Based on a new slow solution for different high rotational radiation-driven winds and the fact that bi-stability allows a change in the line-force parameters (α, k, and δ), the equatorial densities are about 10 2 -10 4 times higher than the polar ones. These values are in qualitative agreement with the observations.

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The ionization structure of early-B supergiant winds

Cited by 25 publications

References 17 publications

Modeling Ultraviolet Wind Line Variability in Massive Hot Stars

Modeling Ultraviolet Wind Line Variability in Massive Hot Stars

Ultraviolet diagnostic of porosity-free mass-loss estimates in B stars

Outflowing disk formation in B[e] supergiants due to rotation and bi-stability in radiation driven winds

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