Rotating massive main-sequence stars: II. Simulating a population of LMC early B-type stars as a test of rotational mixing

By I. Brott, C. Evans, I. Hunter, A. D. Koter, N. Langer, P. Dufton, Matteo Cantiello, C. Trundle, D. Lennon, Selma de Mink and 2 more. 2011

428 citations recorded by the source corpus.

Context. Rotational mixing in massive stars is a widely applied concept, with far-reaching consequences for stellar evolution, nucleosynthesis, and stellar explosions. Aims. Nitrogen surface abundances for a large and homogeneous sample of massive B-type stars in the Large Magellanic Cloud (LMC) have recently been obtained by the ESO VLT-FLAMES Survey of Massive Stars. This sample is the first to cover a broad range of projected stellar rotational velocities, with a large enough sample of high quality data to allow for a statistically significant analysis. Here we use the sample to provide the first rigorous and quantitative test of the theory of rotational mixing in massive stars. Methods. We calculated a grid of stellar evolution models, using the VLT-FLAMES sample to calibrate some of the uncertain mixing processes. We developed a new population-synthesis code, which uses this grid to simulate a large population of stars with masses, ages, and rotational velocity distributions consistent with those from the VLT-FLAMES sample. The synthesized population is then filtered by the selection effects in the observed sample, to enable a direct comparison between the empirical results and theoretical predictions. Results. Our simulations reproduce the fraction of stars without significant nitrogen enrichment. However, the predicted number of rapid rotators with enhanced nitrogen is about twice as large as found observationally. Furthermore, two groups of stars (one consisting of slowly rotating, nitrogen-enriched objects and another consisting of rapidly rotating un-enriched objects) cannot be reproduced by our single-star population synthesis. Conclusions. Physical processes in addition to rotational mixing appear to be required to understand the population of massive mainsequence stars from the VLT-FLAMES sample. We discuss the possible role of binary stars and magnetic fields in the interpretation of our results. We find that the population of slowly rotating nitrogen-enriched stars is unlikely to be produced via mass transfer and subsequent tidal spin-down in close binary systems. A conclusive assessment of the role of rotational mixing in massive stars requires a quantitative analysis that also accounts for the effects of binarity and magnetic fields.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/1bca731e864c08250571df3ee07dfaf9d92980e1

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In Astronomy and Astrophysics

1. Michela Mapelli
2. N. Giacobbo
3. Mario Spera
4. Ilya Mandel
5. C. Conroy
6. P. V. van Dokkum
7. N. Langer
8. Selma de Mink

Citations in the corpus

• A new route towards merging massive black holes (2016, methodology): “When considered in detail, however, in particular the more massive and more metal-rich stars undergo some expansion during core hydrogen burning, even on the quasi-homogeneous path (Brott et al. 2011; Köhler et al. 2015; Szécsi et al. 2015).”
• Progenitors of gravitational wave mergers: binary evolution with the stellar grid-based code ComBinE (2018, methodology): “We thus include stellar tracks for metallicities equal to those of the Large Magellanic Cloud (LMC, Z = ZLMC ≡ 0.0047) and the Small Magellanic Cloud (SMC, Z = ZSMC ≡ 0.0021), which are taken form Brott et al. (2011).”
• PARSEC evolutionary tracks of massive stars up to 350 M ☉ at metallicities 0.0001 ≤ Z ≤ 0.04 (2015, background): “Understanding their evolution is challenged by the complexity of several physical phenomena, as recently reviewed, for example, by Martins & Palacios (2013) who compare STERN (Brott et al. 2011), Geneva (Ekström et al. 2012), FRANEC (Chieffi & Limongi 2013), Padova (Bertelli et al. 2009), MESA (Pax”
• Merging binary black holes formed through chemically homogeneous evolution in short-period stellar binaries (2015, methodology): “Brott et al. (2011a) and Köhler et al. (2015) further explored a larger range of masses and higher metallicities using models where the efficiency of rotational mixing is calibrated against the observed nitrogen abundances of early B type stars in the Large Magellanic Cloud.”
• MESA ISOCHRONES AND STELLAR TRACKS (MIST). I. SOLAR-SCALED MODELS (2016, methodology): “…treatment is often calibrated to fit the observed MSTO of stellar clusters and associations, and is a commonly adopted scheme in many stellar evolution codes (e.g., Demarque et al. 2004; Pietrinferni et al. 2004; Dotter et al. 2008; Brott et al. 2011a; Bressan et al. 2012; Ekström et al. 2012).”
• The R136 star cluster dissected with Hubble Space Telescope/STIS. I. Far-ultraviolet spectroscopic census and the origin of He II λ1640 in young star clusters (2016, methodology): “…the WN5 stars (Crowther et al. 2010), temperatures and luminosities are from spectral type calibrations (Doran et al. 2013), while inferred current masses M and ages τ for O stars are from BONNSAI (Schneider et al. 2014a) using the Bonn evolutionary models (Brott et al. 2011; Köhler et al. 2015).”
• THE ROTATION RATES OF MASSIVE STARS: THE ROLE OF BINARY INTERACTION THROUGH TIDES, MASS TRANSFER, AND MERGERS (2012, methodology): “The internal rotational profile is approximated assuming rigid rotation, which is a reasonable approximation for main-sequence stars (e.g., Brott et al. 2011a).”
• Delay-time distribution of core-collapse supernovae with late events resulting from binary interaction (2017, methodology): “…code MESA, version 7184 (Paxton et al. 2011, 2013, 2015) for nonrotating stars when using our standard metallicity, Z = 0.014, and the Schwarzschild criterion for convection with a stepovershooting parameter αov = 0.335Hp, where Hp is the pressure scale height, as calibrated by Brott et al. (2011).”
• Ultra-stripped supernovae: progenitors and fate (2015, background): “From a density profile analysis of the stellar models evolved by Brott et al. (2011), we find that a10 M⊙ ZAMS star (Z = 0.02, non-rotating) produces a helium core of2.”
• The VLT-FLAMES Tarantula Survey XXVII. Physical parameters of B-type main-sequence binary systems in the Tarantula nebula (2017, neutral): “Also shown are the evolutionary tracks and isochrones of Brott et al. (2011a) for e ff ectively zero initial rotational velocity.”
• Spectroscopy of superluminous supernova host galaxies. A preference of hydrogen-poor events for extreme emission line galaxies (2014, background): “One way to reach these temperatures is by the contribution of massive O stars, especially if these are evolving homogeneously at low metallicity (Brott et al. 2011; Jaskot & Oey 2013).”
• Binary Black Hole Population Properties Inferred from the First and Second Observing Runs of Advanced LIGO and Advanced Virgo (2018, background): “Metallicity has been shown (Kudritzki & Puls 2000; Vink et al. 2001; Brott et al. 2011) to have important effects on stellar mass loss through winds— line-driven winds are quenched in metal-poor progenitors, enabling large BHs to form through direct collapse or postsupernova mass fallback (Heger et…”
• Presupernova Evolution and Explosive Nucleosynthesis of Rotating Massive Stars in the Metallicity Range −3 ≤ [Fe/H] ≤ 0 (2018, methodology): “The adopted initial metallicity is [Fe/H]=−0.45, and the abundances of most of the elements are assumed to be scaled solar, with the exceptions of C, N, O, Mg, and Si, for which we adopt the same scaling reported by Brott et al. (2011) in their Table 1.”
• STRONG NEBULAR LINE RATIOS IN THE SPECTRA of z ∼ 2–3 STAR FORMING GALAXIES: FIRST RESULTS FROM KBSS-MOSFIRE (2014, background): “Aside from producing massive stars that evolve toward hotter Teff while on the main sequence, rapid rotation also results in larger UV luminosities and longer main sequence lifetimes at a given mass and metallicity (Brott et al. 2011).”
• COMPACT BINARY MERGER RATES: COMPARISON WITH LIGO/VIRGO UPPER LIMITS (2015, background): “Evolutionary models show that already at SMC metallicity (20–30% solar) stars up to 60 M⊙ expand to large radii and become red super giants (Brott et al. 2011).”