The Presence of Blood in the Peritoneum.

Hunter, William

doi:10.1016/s0140-6736(02)24750-9

Cited by 4 publications

(17 citation statements)

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“…Brott et al 2009). However, recent results from the VLT‐FLAMES survey Evans et al (2005) have indicated that other mechanisms may affect mixing of material between the interior and the surface Hunter et al (2008b, 2009).…”

Section: Resultsmentioning

confidence: 99%

“…In turn, this has stimulated several recent studies (Wolff, Edwards & Preston 1982; Abt, Levato & Grosso 2002; Strom, Wolff & Dror 2005; Huang & Gies 2006; Martayan et al 2006; Wolff, Strom & Dror 2007; Hunter et al 2008a) of stellar rotation in both field and cluster stars and in different metallicity environments. However, recently both slowly rotating stars with relatively high nitrogen abundance and rapidly rotating stars with relatively low nitrogen abundances (Hunter et al 2008b, 2009) have been identified in the Very Large Telescope – Fibre Large Array Multi Element Spectrograph (VLT‐FLAMES) survey of massive stars (Evans et al 2005). Hence, other mechanisms as well as rotation may be important for mixing nucleosynthetically processed material to the surface, as discussed by Brott et al (2009).…”

Section: Introductionmentioning

confidence: 99%

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Atmospheric parameters and rotational velocities for a sample of Galactic B-type supergiants

Fraser¹,

Dufton²,

Hunter³

et al. 2010

Monthly Notices of the Royal Astronomical Society

111

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High‐resolution optical spectra of 57 Galactic B‐type supergiant stars have been analysed to determine their rotational and macroturbulent velocities. In addition, their atmospheric parameters (effective temperature, surface gravity and microturbulent velocity) and surface nitrogen abundances have been estimated using a non‐local thermodynamic equilibrium grid of model atmospheres. Comparisons of the projected rotational velocities have been made with the predictions of stellar evolutionary models and in general good agreement was found. However, for a small number of targets, their observed rotational velocities were significantly larger than predicted, although their nitrogen abundances were consistent with the rest of the sample. We conclude that binarity may have played a role in generating their large rotational velocities. No correlation was found between nitrogen abundances and the current projected rotational velocities. However, a correlation was found with the inferred projected rotational velocities of the main‐sequence precursors of our supergiant sample. This correlation is again in agreement with the predictions of single star evolutionary models that incorporate rotational mixing. The origin of the macroturbulence and microturbulent velocity fields is discussed and our results support previous theoretical studies that link the former to subphotospheric convection and the latter to non‐radial gravity mode oscillations. In addition, we have attempted to identify differential rotation in our most rapidly rotating targets.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Atmospheric parameters and rotational velocities for a sample of Galactic B-type supergiants

Fraser¹,

Dufton²,

Hunter³

et al. 2010

Monthly Notices of the Royal Astronomical Society

111

View full text Add to dashboard Cite

show abstract

“…Frischknecht et al (2010) and Brott et al (2011a) also consider how rotation is likely to affect the surface abundances of light elements. If we look at a plot of the surface abundance against surface rotation rate, commonly referred to as the Hunter diagram (Hunter et al 2009), for different ages (Fig. 4) we see that there are some very clear differences between the two cases.…”

Section: Resultsmentioning

confidence: 99%

“…The two populations are qualitatively similar to the populations at solar metallicity. We have also plotted the LMC stars observed by Hunter et al (2009). Case 1 Z predicts a very confined distribution of enriched stars, whereas case 2 Z predicts a much wider spread of enrichment.…”

Section: Resultsmentioning

confidence: 99%

Towards a unified model of stellar rotation - II. Model-dependent characteristics of stellar populations

Potter

Tout

Brott³

2012

Monthly Notices of the Royal Astronomical Society

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Rotation has a number of important effects on the evolution of stars. Apart from structural changes because of the centrifugal force, turbulent mixing and meridional circulation caused by rotation can dramatically affect a star’s chemical evolution. This leads to changes in the surface temperature and luminosity as well as modifying its lifetime. Observationally, rotation decreases the surface gravity, causes enhanced mass loss and leads to surface abundance anomalies of various chemical isotopes. The replication of these physical effects with simple stellar evolution models is very difficult and has resulted in the use of numerous different formulations to describe the physics. Using stellar evolution calculations based on several physical models, we discuss the features of the resulting simulated stellar populations which can help to distinguish between the models.

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“…In the case where there is a strong magnetic field, the meridional circulation may be inhibited (Maeder & Meynet 2003), but this conclusion has been questioned by Maeder & Meynet (2005) who found that, if the meridional circulation is neglected, there is insufficient differential rotation to maintain the magnetic dynamo. In particular, if differential rotation is too strongly suppressed by magnetic fields, then it is difficult to explain the existence of slow‐rotating stars with strong nitrogen enrichment (Hunter et al 2009; Meynet, Eggenberger & Maeder 2011). Mixing may be driven either by Parker’s instability or by the horizontal rotation‐driven turbulence that itself is responsible for the rotationally driven mixing.…”

Section: Spin‐down Time‐scale and Magnetic Windmentioning

confidence: 99%

Spin-down of massive rotating stars

Lau¹,

Potter²,

Tout³

2011

Monthly Notices of the Royal Astronomical Society

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Models of rapidly rotating massive stars at low metallicities show significantly different evolution and higher metal yields compared to non‐rotating stars. We estimate the spin‐down time‐scale of rapidly rotating non‐convective stars supporting an α–Ω dynamo. The magnetic dynamo gives rise to mass‐loss in a magnetically controlled stellar wind and hence stellar spin‐down owing to loss of angular momentum. The dynamo is maintained by strong horizontal rotation‐driven turbulence which dominates over the Parker instability. We calculate the spin‐down time‐scale and find that it could be relatively short, a small fraction of the main‐sequence lifetime. The spin‐down time‐scale decreases dramatically for higher surface rotations suggesting that rapid rotators may only exhibit such high surface velocities for a short time, only a small fraction of their main‐sequence lifetime.

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The Presence of Blood in the Peritoneum.

Cited by 4 publications

References 0 publications

Atmospheric parameters and rotational velocities for a sample of Galactic B-type supergiants

Atmospheric parameters and rotational velocities for a sample of Galactic B-type supergiants

Towards a unified model of stellar rotation - II. Model-dependent characteristics of stellar populations

Spin-down of massive rotating stars

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