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Discussions about Z effects on the Conti scenario Geneva, 1983

Discussions about Z effects on the Conti scenario Geneva, 1983. Peter sitting on pure Z=1 materials in Arapahoe Peak Boulder, 1989. Peter during a bicycle trip Geneva 2002. Peter with some of his many disciples… Boulder, 2003. MASSIVE STARS EVOLUTION. in collaboration with :

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Discussions about Z effects on the Conti scenario Geneva, 1983

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  1. Discussions about Z effects on the Conti scenario Geneva, 1983

  2. Peter sitting on pure Z=1 materials in Arapahoe Peak Boulder, 1989

  3. Peter during a bicycle trip Geneva 2002

  4. Peter with some of his many disciples… Boulder, 2003

  5. MASSIVE STARS EVOLUTION in collaboration with : Georges Meynet Raphael Hirschi (Univ. Keele) Patrick Eggenberger (Univ. Liege) Sylvia Ekström Cyril Georgi

  6. MASSIVE STARS: High T Low  MASS LOSS : MIXING: shear ~ thermal diffusivity Mass loss and mixing strongly favoured !

  7. Both effects interact: • Mass loss removes angular momentum • Rotation enhances the M- loss rates • STRUCTURE • Oblateness • MASS LOSS • Enhanced winds • Anisotropies • MIXING • Meridional circul. • Shears • Hzt. turbulence Rotation in B stars Huang & Gies (2006); see also Conti & Ebbets 1977 - Peak of Vrot = 200 km/s

  8. ROTATIONAL DISTORTION ACHERNAR ~9.6 Msol Domiciano de Souza et al. 2003 : difficulty ? Carciofi et al. 2008: equatorial disk Re/Rp=1.5 ROCHE MODEL OK for ω =0.992

  9. Von Zeipel (1924) Frad geff  Teff ~ geff 1/4

  10. Altair 1.8 Msol ω =0.9 GRAVITY DARKENING Teff(pole)/Teff(equateur)=1.23-1.27 Confirmation of Von Zeipel Peterson et al. 2006 Monnier et al. 2007 The exponent may be smaller ~0.19 Monnier, 2007

  11. STELLAR WINDS & ROTATION Owocki 1996, Maeder, 1999 Enables a massive star to lose lots of mass and little angular momentum  GRBs iso mass loss

  12. ACHERNAR HAS POLAR WINDS 9.6 Msol Ve=470 km/s ~91% Vcrit Mass of the disk =4.1 10-10Msol Mass loss =1.3 10-8 Msol/y Polar mass flux 7 10-9 Msol y-1 sr-1 Disk in Keplerian rotation Meilland et al. 2007 Intensity map in the continuum at 2.15 micron (SIMECA code)

  13. (N/H) depend on • v sin i • M • age • Z, etc… SURFACE ENRICHMENTS

  14. Stars in extended regions around N11 and NGC 2004 in the LMC. Spread in masses and ages. Sample biased toward low v sini « The observation challenges the concept of rotational mixing » Hunter et al. 2008

  15. One must not assumelog (N/H) = f(v sini) But log (N/H) = f(v sini, M, age, Z….) Mass effect Age effect end of MS phase beginning of MS phase

  16. MS stars between 14 and 20 MO in the list by Hunter et al. 2008 Gr I disappeared, except binaries lower M (~12 MO instead of 17 MO) Gr II : evolved stars • It would be useful • to account for • gravity darkening • in v sin i • to separate gravity • effects due to rot. • and evolution • in M determinations

  17. ABUNDANCES: Galaxy: [N/H] for O-stars : ~ 0.5 up to 0.8-1.0 dex < 20 M  B – dwarfs : ~ 0.5 dex > 20 M  B – giants , supg. : ~0.5 -0.7 dex Ref: Villamariz & Herrero ’02; Smartt ’02;Herrero’03;Venn & Przybilla03;Trundle et al.’07 LMC: [N/H] for B-supg. : ~ 0.3 - 0.8 dex < 20 M  B – dwarfs : ~ 0.7- 0.9 dex B – giants, supg. :  1.1 -1.2 dex > 20 M  B – giants , supg. :  1.3 dex Ref: Herrero’03;Trundle et al. ’07;Hunter et al.’07 SMC: [N/H] O-stars, A-F supg. : 1.5 -1.7 dex < 20 M  B – dwarfs :  1.1 dex B – giants, supg. :  1.5 dex > 20 M  B – giants , supg :  1.9 dex Ref: Heap & Lanz’06; Venn & Przybilla’03; Bouret et al.’03;Trundle et al.’07; Hunter et al.’07

  18. Gradients of  steeper at lower metallicity 20 MO More efficient mixing of the chemical elements at lower Z MM’ 01

  19. 60 Msol, Z = 0.00001 2/3 of the Main Sequence phase spent near the break-up limit

  20. MASS LOSS DUE TO THE APPROACH OF THE BREAK-UP LIMIT Z=10-8 300 km/s End MS 800 km/s ! Solar Z  radiative M - loss Low Z stars  rotational M-loss Age in Myr

  21. Zsurf/Zini=1 Zsurf/Zini=64 14N Yc= 0.12 12C Yc= 0.40 16O Zsurf/Zini=392 Zsurf/Zini=1336 Yc= 0.08 Z=10-8 Yc= 0.02

  22. ΔY/ΔZ= 70-130 Also, ΔY/ΔZ > 70, cf.  CenMaeder & Meynet 2006

  23. Most extreme stars Continuous line: models at Z=10-5 (MM02) Broken line: the same with larger N yield Red: new models with fast rotation belowZ=10-5 Chiappini, Hirschi, Meynet, Ekström, Maeder., Matteucci 2006 Confirmed by Fabbian, Nissen, Asplund, Pettini, Ackerman 2008

  24. Gamma-Ray Bursts (GRBs) Collapsar model (Woosley 1993) Massive star collapsing in a fast spinning BH • Composition: from SNIbc • (WC-WO stars) • Rotation: J > 1016 cm2 s-1 • Statistics: ~1GRB /1000 SN • more at lower Z (up to SMC) • Le Floch et al. 2003;Stanek et al. 2006 Georgy et al. 2008

  25. GRBs Difficulty: remove M without loosing too much angular momentum  homogeneous evolution Avoid the red MM 2006 Yoon & Langer 2005; cf. Maeder, 1987 - Homogeneous evolution. Possible, but composition not corresponding !

  26. Anisotropic winds • keep high rotation • more M loss 0 2 4 (106yr) Meynet & Maeder 2006 Angular momentum in the central 3 MO = 8 x 1016 cm2 s-1 while j= 1016 cm2 s-1 is the limit.

  27. Evolution of All Stellar Generations = f (M, Z, He, mass loss, rotation, binaries, magn. field, ……) • Lifetimes, tracks • Asteroseismology • Evolution properties Be, B[e], • LBV, WR stars in galaxies • Nebulae • Evolution of rotation • Cepheid properties • Surface abundances in massive • stars and red giants • Primary N • Pre – supernova stages • Yields and nucleosynthesis • Rotation periods of pulsars • Final masses • Collapsars, γ- bursts, ….

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