A theoretical and experimental study of the bonding in PF<sub>3</sub>·BH<sub>3</sub>

Hillier, Ian H.; Marriott, J. C.; Saunders, V. R.; Ware, Mike; Lloyd, D. R.; Lynaugh, N.

doi:10.1039/c29700001586

Cited by 37 publications

(24 citation statements)

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“…Therefore, in the calculation of line profiles, microturbulence has been included as an extra free parameter. Metal ion populations and line profiles were calculated using mainly the atomic data of Becker & Butler (1988, 1989, 1990. Such calculations explicitly include the effects of the relevant ions on the radiation field.…”

Section: B -T Y P E S U P E R G I a N T A N A Ly S I Smentioning

confidence: 99%

“…We use the non-LTE code of Hillier & Miller (1998) which iteratively solves the transfer equation in the co-moving frame subject to statistical and radiative equilibria in an expanding, spherically symmetric and steady-state atmosphere. Relative to earlier versions of this code (Hillier 1987(Hillier , 1990, two major enhancements have been incorporated, of particular relevance to WC-type stars, specifically (i) line blanketing and (ii) clumping.…”

Section: Techniquementioning

confidence: 99%

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Chemical abundances and winds of massive stars in M31: a B-type supergiant and a WC star in OB 10

Smartt

Crowther

Dufton

et al. 2001

Monthly Notices of the Royal Astronomical Society

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We present high quality spectroscopic data for two massive stars in the OB 10 association of M31, OB 10‐64 (B0 Ia) and OB 10‐WR1 (WC6). Medium resolution spectra of both stars were obtained using the ISIS spectrograph on the William Herschel Telescope. This is supplemented with Hubble Space Telescope STIS UV spectroscopy and Keck I HIRES data for OB 10‐64. A non‐local thermodynamic equilibrium (LTE) model atmosphere and abundance analysis for OB 10‐64 is presented, indicating that this star has similar photospheric CNO, Mg and Si abundances to solar neighbourhood massive stars. A wind analysis of this early B‐type supergiant reveals a mass‐loss rate of M˙=1.6×10−6 M⊙ yr−1, and v∞=1650 km s−1. The corresponding wind momentum is in good agreement with the wind momentum–luminosity relationship found for Galactic early‐B supergiants. Observations of OB 10‐WR1 are analysed using a non‐LTE, line‐blanketed code, to reveal approximate stellar parameters of log L/L⊙∼5.7, T∗∼75 kK, v∞∼3000 km s−1, M˙/(M⊙ yr−1)∼10−4.3 adopting a clumped wind with a filling factor of 10 per cent. Quantitative comparisons are made with the Galactic WC6 star HD 92809 (WR23) revealing that OB 10‐WR1 is 0.4 dex more luminous, though it has a much lower C/He ratio (∼0.1 versus 0.3 for HD 92809). Our study represents the first detailed, chemical model atmosphere analysis for either a B‐type supergiant or a Wolf–Rayet (WR) star in Andromeda, and shows the potential of how such studies can provide new information on the chemical evolution of galaxies and the evolution of massive stars in the local Universe.

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Section: B -T Y P E S U P E R G I a N T A N A Ly S I Smentioning

confidence: 99%

Section: Techniquementioning

confidence: 99%

Chemical abundances and winds of massive stars in M31: a B-type supergiant and a WC star in OB 10

Smartt

Crowther

Dufton

et al. 2001

Monthly Notices of the Royal Astronomical Society

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“…In order to relate the observed P C values to physical characteristics of the stellar winds we have used the Monte Carlo code described by Hillier (1991) to compute polarization spectra. We used a source function computed for the He ii l5412 emission line by Crowther (personal communication) using Hillier's standard model code (Hillier 1990) as an input for the analysis, and adopted a simple function for the latitude dependence of wind density,…”

Section: R a D I At I V E T R A N S F E R M O D E L Smentioning

confidence: 99%

A spectropolarimetric survey of northern hemisphere Wolf–Rayet stars

Harries¹,

Hillier²,

Howarth³

1998

Monthly Notices of the Royal Astronomical Society

111

131

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We present a homogeneous, high signal‐to‐noise spectropolarimetric survey of 16 northern hemisphere Wolf–Rayet (WR) stars. A reduction in polarization at emission‐line wavelengths — the ‘line effect’— is identified in four stars: WRs 134, 137, 139, and 141. The magnitude of the effect in WR 139 (V444 Cyg) is variable, while WR 136, previously reported to show the line effect, does not show it in our data. Assuming the line effect generally to arise from axisymmetric distortions of stellar winds, we show that a model in which all WRs have the same intrinsic (equator‐on) polarization, with the observed variations solely a result of inclination effects, is inconsistent with the observations. A model in which the intrinsic polarizations are uniformly distributed is more plausible, but best‐fitting results are obtained if the distribution of polarizations is biased towards small values, with only ∼ 20 per cent of stars having intrinsic polarizations greater than ∼ 0.3 per cent. Radiative transfer calculations indicate that the observed continuum polarizations can be matched by models with equator:pole density ratios of 2–3. The model spectra have electron‐scattering wings that are significantly stronger than observed (in both intensity and polarized flux), confirming that the winds of stars showing intrinsic polarization must be clumped on small scales as well as being distorted on large scales. We combine the results of our survey with observations from the literature to give a sample of 29 stars which have both accurate spectropolarimetric observations and physical parameters derived from standard‐model analyses. We find that the line‐effect stars are clustered at high M, L in the luminosity–mass‐loss rate plane (although they are unexceptional in the terminal velocity–subtype and the surface‐mass‐flux–temperature planes). The mass‐loss rates derived from radio‐continuum observations for these stars are in good accord with the results of optical emission‐line analyses, suggesting that (i) the wind structure of line‐effect stars has a density contrast which is effectively constant with radius, and (ii) the high M values may be artefacts of large‐scale wind structure. Assuming that observed spectroscopic and photometric variability of the line‐effect stars is related to the WR rotation period, we compute equatorial rotation velocities. These velocities correspond to ∼ 10 per cent of the core breakup rates, and may be large enough to produce significant wind‐compression effects according to the models of Ignace, Cassinelli & Bjorkman.

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“…A possible explanation for this observation may be seen in the fact that, contrary to chalcogen atoms, BH 3 groups are σ-acceptors with strongly reduced π-donor capabilities. A small degree of π-back donation by BH 3 was postulated very early in the investigations of the bonding in PF 3 ·BH 3 [34,35] and CO·BH 3 . [34,36] More recent theoretical studies including natural energy decomposition analyses seem to confirm the effect of hyperconjugation for CO·BH 3 [37,38] and PF 3 ·BH 3 .…”

Section: Crystal Structure Determinationmentioning

confidence: 97%

P₈O₁₂·2BH₃ − The Borane Adduct of a New Molecular Phosphorus Oxide

Tellenbach

Jansen

2003

Eur J Inorg Chem

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P 4 O 6 ·BH 3 , which readily forms from P 4 O 6 and Me 2 S·BH 3 in a stoichiometric reaction, dimerizes spontaneously at −30°C in a concentrated toluene solution resulting in the crystallization of P 8 O 12 ·2BH 3 (1). The synthesis of 1 represents the first selective interconnection of molecular phosphorus chalcogenides leading to the formation of a new, flexible P 8 O 12 cage. The thermodynamic driving force for the dimerization reaction results from a gain of enthalpy due to enhanced P−O double-bond contributions and a relief of angular strain. In terms of kinetics, the behavior of P 4 O 6 ·BH 3 , differing from that of other P 4 O 6 derivatives, is caused by the low π-donor

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A theoretical and experimental study of the bonding in PF₃·BH₃

Cited by 37 publications

References 0 publications

Chemical abundances and winds of massive stars in M31: a B-type supergiant and a WC star in OB 10

Chemical abundances and winds of massive stars in M31: a B-type supergiant and a WC star in OB 10

A spectropolarimetric survey of northern hemisphere Wolf–Rayet stars

P₈O₁₂·2BH₃ − The Borane Adduct of a New Molecular Phosphorus Oxide

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A theoretical and experimental study of the bonding in PF3·BH3

Cited by 37 publications

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Chemical abundances and winds of massive stars in M31: a B-type supergiant and a WC star in OB 10

Chemical abundances and winds of massive stars in M31: a B-type supergiant and a WC star in OB 10

A spectropolarimetric survey of northern hemisphere Wolf–Rayet stars

P8O12·2BH3 − The Borane Adduct of a New Molecular Phosphorus Oxide

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A theoretical and experimental study of the bonding in PF₃·BH₃

P₈O₁₂·2BH₃ − The Borane Adduct of a New Molecular Phosphorus Oxide