Stars rotate throughout the Universe

1. Stars rotate throughout the Universe A. Maeder & G. Meynet

2. Old… … but quite topical nowadays Star deformation due to its fast axial rotation Link between Long GRB and Hypernova confirmed Dominiciano de Souza et al. 2003 Hjorth et al. 2003

3. OBSERVATIONAL EVIDENCES FOR MIXING • Extended cluster MSMaeder, 76; Mermilliod et al. 93 • ON starsWalborn, 76, 2002; • Heap & Lanz 2003 • Fast rotators with He, N excessesLyubimkov 91-98; Daflon et al. 99, 01 • Herrero et al. 92; Villamariz et al. 02 • He, N excesses in B, A, F supergiantsGies & 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 1987AFransson et al. 89 • Boron depletion in rotating B-starsFliegner et al. 96;Venn et al. 96, 2002 • Transition WN/WC starsLanger 91; Crowther 95, 02; • Morris et al. 99 • Blue/ Red supergiant ratios at various ZLanger & Maeder 96; • Maeder & Meynet 2002

4. 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…

5. STRUCTURE cf. Kippenhahn & Thomas ‘70 The equation scheme may be written with some modifications for Meynet & Maeder‘97 SURFACE DISTORSIONS CHANGE OF Teff

6. Cells of meridional circulation GRATTON- ÖPIK CELL Zahn 1992 Maeder & Zahn 1998.

7. Evolution Meridional circulation Shear mixing Horizontal turbulence Gradients of Transport of the chemical species Transport of the angular momentum Advection ! Diffusion !

8. WHY MIXING IN MASSIVE STARS ? FOR HIGH M MIXING TIME < MS TIMESCALE

9. WIND THEORY IN ROTATING STARS Maeder, 1999 iso mass loss Short shell ejection For stellar formation also

10. van Boekel et al. 2003

11. The present wind around Eta Carinae is elongated along a direction aligned with the Homunculus Nebula Smith et al. 2003 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

12. Idem with Teff =25000 K

13. Stellar winds Transport Contraction/expansion Z=0.02 Z=0.00001 More mixing at lower Z due compactness and smaller Gratton-Öpik circulation Meynet & Maeder 2002

14. From 19 clusters in Galaxy, LMC & SMC Is this a general trend ? What at Z = 0 ? Maeder, Grebel, Mermilliod 1999

15. 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

16. 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 = 0.5–0.8 in SMCcf. Maeder & Meynet 2001

17. Y with rotation Mr/Msun With rotation: - Larger core - More He in shell - H shell less active - no intermed. conv. zone RSG

19. 300 km/s Z=0.020 200 km/s 200 N/C growsduring the MS, even for early B stars (Lyubimkov 1996) OK with B, A supergiants (Gies & Lambert 1992; Lennon 1994; Venn 1998)

20. O-type stars in the SMC Nine of 17 O-type stars show a surface enrichment in N up to a solar level, [N]=7.92. Heap and Lanz 2003

21. Max/ini N/H =40 Venn & Przybilla 2003

22. 9 Msol When Z Surface enrichments

23. NITROGEN HII regions Pagel 1997 Garnett 1990 Metal-poor dwarfs of the Solar neighborhood DLA Pettini et al 2002 Carbon et al. 1987

24. This mechanism • works best in intermediate • mass stars • steeper • rotation profile • - H- and He shells • are closer • Z=0.00001 14 N S-process reinforced

25. Increase of primary N production when rotation increases

27. AT LOW Z: HUGE AMOUNTS OF PRIMARY N For Z=0.004 and Z=0.020, nearly no primary N

28. Rotating models

29. Israelian et al. 2004

30. Log (C/O) vs 12+Log(O/H) for extragalactic HII regions and stars What is the cause of the change of slope ? Intermediate mass stars ? From Henry et al 2000 High metallicity massive stars ? 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

31. NUMBER RATIOS OF MASSIVE STARSIN NEARBY GALAXIES GALAXY Z WR/O WC/WR RSG/WR !

32. Weak winds (low Z) Maeder 92 Ejecta rich in 16O Z= 0.001 40Msol, Z=0.001 Strong winds (high Z) Ejecta rich in 4He and 12C Z= 0.020 40Msol, Z=0.020

33. More recent works favours massive stars as the source of carbon at high metallicity Gustafsson et al. 1999 ``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.’’

34. YIELDS with rotation and mass loss Mass fractions ejected Hirschi et al. 2004

35. Yields in 12C Models with rotation produce much more Carbon

36. See also Carigi 2003; Chiappini et al. 2003 Prantzos 2003 Rotating massive stars ~ AGB stars, but synthetic models…

37. C/O versus O/H Behaviour at low metallicity depends on the mass range not so much on rotation

38. FINAL MASSES