Stars rotate throughout the Universe A. Maeder & G. Meynet Star deformation due to its fast axial rotation but quite topical nowadays Link between Long GRB and Hypernova confirmed Dominiciano de Souza et al Hjorth et al Old OBSERVATIONAL EVIDENCES FOR MIXING Extended cluster MS Maeder, 76; Mermilliod et al. 93 ON stars Walborn, 76, 2002; Heap & Lanz 2003 Fast rotators with He, N excesses Lyubimkov 91-98; Daflon et al. 99, 01 Herrero et al. 92; Villamariz et al. 02 He, N excesses in B, A, F supergiants Gies & Lambert 92; Lennon 92, 2002 Venn 95, 2002 Venn and Przybilla 2003 Strong He, N excess in SMC supg. Venn 95, 2002 He, N excesses in SN 1987A Fransson et al. 89 Boron depletion in rotating B-stars Fliegner et al. 96; Venn et al. 96, 2002 Transition WN/WC stars Langer 91; Crowther 95, 02; Morris et al. 99 Blue/ Red supergiant ratios at various Z Langer & Maeder 96; Maeder & Meynet 2002 PHYSICS OF ROTATION Oblatness (interior, surface) New structure equations Shellular rotation Meridional circulation Shear instabilities + diffusion Horizontal turbulence Advection + diffusion of angular momentum Transport + diffusion of the chemical elements Increase of the mass loss by rotation Anisotropic losses of angular momentum Pinsonneault, Sofia, Langer Talon & Zahn Heger & Woosley Charbonnel & Palacios Denissenkov etc STRUCTURE cf. Kippenhahn & Thomas 70 The equation scheme may be written with some modifications for Meynet & Maeder 97 SURFACE DISTORSIONS CHANGE OF Teff GRATTON- PIK CELL Cells of meridional circulation Zahn 1992 Maeder & Zahn 1998. Evolution Meridional circulation Shear mixing Horizontal turbulence Gradients of Transport of the chemical species Transport of the angular momentum Advection !Diffusion ! FOR HIGH M MIXING TIME < MS TIMESCALE WHY MIXING IN MASSIVE STARS ? iso mass loss WIND THEORY IN ROTATING STARS For stellar formation also Maeder, 1999 Short shell ejection van Boekel et al. 2003 The present wind around Eta Carinae is elongated along a direction aligned with the Homunculus Nebula Smith et al also indicate latitude dependent wind velocity, with the highest velocities near the poles Support polar enhanced mass loss. Eta Carinae should rotate at about 90% of the break-up velocity Idem with Teff =25000 K Z=0.02 Z= More mixing at lower Z due compactness and smaller Gratton-pik circulation Meynet & Maeder 2002 Stellar winds Transport Contraction/expansion Maeder, Grebel, Mermilliod 1999 Is this a general trend ? What at Z = 0 ? From 19 clusters in Galaxy, LMC & SMC When rotation is accounted for, the ages are found 25 % larger. Pleiades: reconcile with age from Li depletion in low M stars. Martin et al. 1998 B/R PROBLEM Lots of RSG observed at low Z, but current models predict none. B/R ~ 50 Langer & Maeder, 95 Models with rotation are OK with B/R = 0.50.8 in SMC cf. Maeder & Meynet 2001 with rotation With rotation: - Larger core - More He in shell - H shell less active - no intermed. conv. zone RSG Y M r /M sun N/C grows during the MS, even for early B stars (Lyubimkov 1996) OK with B, A supergiants (Gies & Lambert 1992; Lennon 1994; Venn 1998) 300 km/s 200 Z= km/s Nine of 17 O- type stars show a surface enrichment in N up to a solar level, [N]=7.92. Heap and Lanz 2003 O-type stars in the SMC Venn & Przybilla 2003 Max/ini N/H =40 9 M sol When Z Surface enrichments Pettini et al 2002 Metal-poor dwarfs of the Solar neighborhood Carbon et al HII regions DLA Pagel 1997 Garnett 1990 NITROGEN This mechanism works best in intermediate mass stars -steeper rotation profile - H- and He shells are closer Z= N S-process reinforced Increase of primary N production when rotation increases For Z=0.004 and Z=0.020, nearly no primary N AT LOW Z: HUGE AMOUNTS OF PRIMARY N Rotating models Israelian et al. 2004 HII regions from Garnett et al. 95, 97, 99 Izotov and Thuan 99 Kobulnicky and Skillman 88 Stellar data from Gustafsson et al 99 Gummersbach et al. 98 Tomkin et al 92 Log (C/O) vs 12+Log(O/H) for extragalactic HII regions and stars From Henry et al 2000 What is the cause of the change of slope ? Intermediate mass stars ? High metallicity massive stars ? NUMBER RATIOS OF MASSIVE STARS IN NEARBY GALAXIES M ~ M ~4 LMC SMC GALAXY Z WR/O WC/WR RSG/WR ! Maeder 92 Weak winds (low Z) Ejecta rich in 16 O Strong winds (high Z) Ejecta rich in 4 He and 12 C 40Msol, Z= Msol, Z= He 12 C 16 OZ He 12 C 16 OZ Z= Z= 0.020 More recent works favours massive stars as the source of carbon at high metallicity Gustafsson et al ``Our results are consistent with carbon enrichment by superwind of metal-rich massive stars but inconsistent with a main origin of carbon in low mass stars Carigi 2000 ``In the solar vicinity, the increase of C/O with Z is due to massive stars alone. YIELDS with rotation and mass loss Mass fractions ejected Hirschi et al. 2004 Yields in 12 C Models with rotation produce much more Carbon Prantzos 2003 Rotating massive stars ~ AGB stars, but synthetic models See also Carigi 2003; Chiappini et al. 2003 Behaviour at low metallicity depends on the mass range not so much on rotation C/O versus O/H FINAL MASSES