Stellar evolution with rotation. VII. - Low metallicity models and the blue to red supergiant ratio in the SMC

By Andre Maeder, G. Meynet. 2001

313 citations recorded by the source corpus.

We calculate a grid of models with and without the eects of axial rotation for massive stars in the range of 9t o 60M and metallicity Z =0 :004 appropriate for the SMC. Remarkably, the ratios =crit of the angular velocity to the break{up angular velocity grow strongly during the evolution of high mass stars, contrary to the situation at Z =0 :020. The reason is that at low Z, mass loss is smaller and the removal of angular momentum during evolution much weaker, also there is an ecient outward transport of angular momentum by meridional circulation. Thus, a much larger fraction of the stars at lower Z reach break{up velocities and rotation may thus be a dominant eect at low Z. The models with rotation well account for the long standing problem of the large numbers of red supergiants observed in low Z galaxies, while current models with mass loss were predicting no red supergiants. We discuss in detail the physical eects of rotation which favour a redwards evolution in the HR diagram. The models also predict large N enrichments during the evolution of high mass stars. The predicted relative N{enrichments are larger at Z lower than solar and this is in very good agreement with the observations for A{type supergiants in the SMC.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/d9f726b64c4bb868dfcefc608367d162f785c5c7

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In Astronomy and Astrophysics

1. N. Langer
2. S. Smartt
3. Stan Woosley
4. G. Meynet
5. Michela Mapelli
6. N. Smith
7. Selma de Mink
8. R. Hirschi

In Instrumentation

1. S. Smartt
2. N. Langer
3. N. Smith
4. A. Chieffi
5. M. Limongi
6. C. Conroy
7. G. Meynet
8. Robert G. Izzard

Citations in the corpus

• Stellar evolution with rotation XI. Wolf-Rayet star populations at different metallicities (2004, methodology): “Let us recall also that at low metallicity, for those stars which do not already enter the WR phase during the MS phase, the evolution towards the red supergiant stage is favoured when rotation is included in the stellar model (Maeder & Meynet 2001).”
• MESA ISOCHRONES AND STELLAR TRACKS (MIST). I. SOLAR-SCALED MODELS (2016, result): “However, Maeder & Meynet (2001) found that the inclusion of rotation in their models produced more RSGs at low metallicities, which dramatically lowered the predicted BSG/RSG ratio in the SMC and brought the model prediction into better agreement with the observations.”
• Evolution towards the critical limit and the origin of Be stars (2007, background): “This trend was already put in evidence by Maeder & Meynet (2001).”
• Stellar evolution with rotation and magnetic fields III. The interplay of circulation and dynamo (2005, background): “The effects of rotation are even more important at metallicities Z lower than solar (Maeder & Meynet 2001).”
• Transport and mixing in the radiation zones of rotating stars. I. Hydrodynamical processes (2004, result): “…these models are in better agreement with observational data than models without rotational mixing: they account for the observed surface composition, andthey predict the correct ratio between red and blue supergiants observed in open clusters and in the Magellanic clouds (Maeder & Meynet 2001).”
• The Effect of Massive Binaries on Stellar Populations and Supernova Progenitors (2007, background): “For example Maeder & Meynet (2001) find that the BSG to RSG ratio is decreased rather than increased by rotation owing to a change of the internal helium gradient at the hydrogenburning shell.”
• The VLT-FLAMES survey of massive stars: evolution of surface N abundances and effective temperature scales in the Galaxy and Magellanic Clouds (2007, methodology): “The SMC evolutionary models from the Geneva group (Meynet & Maeder 2000; Maeder & Meynet 2001) show that between the end of the main sequence and the red supergiant phase at log(Teff) = 3.9, there is a low level of nitrogen enrichment for 15-25M⊙ stars of approx 0.1 dex in the SMC. Lower mass…”
• Presupernova Evolution and Explosive Nucleosynthesis of Rotating Massive Stars in the Metallicity Range −3 ≤ [Fe/H] ≤ 0 (2018, background): “The effect of rotation on the evolutionary path of a massive star in the HR diagram in the central H-burning phase is twofold (Maeder & Meynet 2000, 2001, 2012; Meynet & Maeder 2000, CL13).”
• Fourier method of determining the rotational velocities in OB stars (2007, background): “Equally important, the coupling with stellar winds imposes a dependence of the rotational velocity itself on metallicity during the evolution of high-mass stars (Maeder & Meynet 2001).”
• Stellar evolution with rotation - XIII. Predicted GRB rates at various Z (2005, background): “The models reproduce many observational features at various metallicities very well, like surface enrichment (Meynet & Maeder 2002b) and ratios between red and blue supergiants (Maeder & Meynet 2001, hereinafter Paper VII).”
• The Geneva stellar evolution code (2008, unknown): “…+ Dh)[ϕ δ ∇μ(1 + KDh ) + (∇ad − ∇rad)] × Hp gδ [ α 4 ( f Ω d lnΩ d ln r )2 − (∇′ − ∇) ] (36) where f is a numerical factor equal to 0.8836, K is the thermal diffusivity and (∇′ − ∇) expresses the difference between the internal nonadiabatic gradient and the local gradient (Maeder and Meynet 2001).”
• Stellar evolution with rotation XII. Pre-supernova models (2004, background): “In particular, it has been shown that rotating models well reproduce the observed surface enrichments (Heger & Langer 2000; Meynet & Maeder 2000), the ratios of blue to red supergiants in the Small Magellanic Cloud (Maeder & Meynet 2001), and the variations of the Wolf–Rayet (WR hereinafter) star po”
• The Evolution of Massive Stars. I. Red Supergiants in the Magellanic Clouds (2003, background): “Maeder & Meynet (2001) find that more RSGs are produced in the models at SMC-like metallicities when rotation is included.”
• Effects of rotation on the evolution of primordial stars (2008, background): “…reproduce the observed surface abundances (Heger & Langer 2000; Meynet & Maeder 2000), the ratio of blue-to-red supergiants at low metallicity (Maeder & Meynet 2001), the variation with metallicity of the WR/O ratios and of the numbers of type Ibc to type II supernovae (Meynet & Maeder 2003,…”
• The VLT-FLAMES survey of massive stars: constraints on stellar evolution from the chemical compositions of rapidly rotating Galactic and Magellanic Cloud B-type stars (2009, methodology): “For example, rotation has been used as an explanation of blue to red supergiant ratios (Maeder & Meynet 2001) and of Wolf-Rayet populations as a function of metallicity (Meynet & Maeder 2005; Vink & de Koter 2005).”
• On the Collapsar Model of Long Gamma-Ray Bursts:Constraints from Cosmic Metallicity Evolution (2005, background): “Current evolutionary models that include rotation predict extended envelopes for the vast majority of massive stars in the Galaxy or Magellanic Clouds — in agreement with the number of blue and red supergiants (Maeder & Meynet 2001, 2005).”
• A UBVR CCD Survey of the Magellanic Clouds (2001, background): “Maeder & Meynet (2001) have recently reported a breakthrough on the theoretical front, in terms of understanding the effect of rotation on the evolution of low-metallicity stars.”
• Fast rotating massive stars and the origin of the abundance patterns in galactic globular clusters (2006, background): “As shown by Sackmann & Anand (1970) and later by Langer (1998) and Maeder & Meynet (2001), massive stars do reach the so-called critical velocity2 early on the main sequence if (1) they start their evolution with a sufficiently high initial rotation rate, (2) they do not lose too much angular…”