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Stellar evolution with rotation

Stellar evolution with rotation. Wolf-Rayet stars at solar metallicity. WR Nebula WR124, taken with HST. Tim van Werkhoven. Wolf-Rayet stars Evolution of rotational speed Evolution in H-R diagram Evolution of mass Comparison of (non)-rotational models WR-subphases

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Stellar evolution with rotation

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  1. Stellar evolution with rotation Wolf-Rayet stars at solar metallicity WR Nebula WR124, taken with HST Tim van Werkhoven

  2. Wolf-Rayet stars Evolution of rotational speed Evolution in H-R diagram Evolution of mass Comparison of (non)-rotational models WR-subphases Comparison with observation Conclusion Stellar evolution with rotation Tim van Werkhoven

  3. Massive, ~ 20 Msun Mass loss ~ 10-6-10-5 Msun/y (compare 10-14 Msun/y) Hot, ~50,000 K Luminous, ~105-106 Lsun Extremely rare because of short life Different types, WC, WN and WO (Carbon, Nitrogen, Oxygen line-features) WR stars believed to be at the end of their lives Progenitors of supernovae and γ-ray bursts Stellar evolution: Wolf-Rayet stars Tim van Werkhoven

  4. Stellar evolution: Rotational speed Rotational speed evolution tracks for different stars Tim van Werkhoven

  5. Stellar evolution: Rotational speed Ω/Ω-critical-evolution tracks for different stars Tim van Werkhoven

  6. Stellar evolution: Rotational speed Steep drops: end of MS (bi-stability limit) Dependent on initial mass Higher masses lose more angular momentum (more wind) Tim van Werkhoven

  7. Stellar evolution: Rotational speed Left (85 Msun): Mass loss, Ω, R, v 25Msun, H-burning stops R,Ω,P,v~ Right (25 Msun) P, because T, R At the end, v because you see deeper layers Evolution for 85 and 25 Msun stars Tim van Werkhoven

  8. Stellar evolution: H-R Diagram Evolution in the H-R diagram Tim van Werkhoven

  9. Stellar evolution: H-R Diagram Evolution in the H-R diagram for a 120 Msun star Tim van Werkhoven

  10. More luminous M<30Msun, bandwidth is enlarged (larger He-core) M>50Msun, bandwidth is reduced (surface He enhancement leads to bluer track) If no rotation is taken into account, masses are over-estimated Possible result of mass-discrepancy (Herrero et al. 2000) For 120 Msun Wider range in L Stellar evolution: H-R Diagram Tim van Werkhoven

  11. Stellar evolution: Mass change Initial versus final mass for different models Tim van Werkhoven

  12. In general: lower final mass For M~55 Msun, rotation does not matter Caused by different evolutionary tracks Corresponds well to observations Average mass for WC stars 12 ± 3 Msun (6 star avg.) Higher masses than the older model Possible result of mass-discrepancy (Herrero et al. 2000) Stellar evolution: Mass change Tim van Werkhoven

  13. Stellar evolution: Comparison Comparison: Same L when entering WR-phase -> same mass! (different evolution) No rotation -> LBV phase No rotation -> lower mass WR-phase Evolution models for a 60 Msun star Tim van Werkhoven

  14. Stellar evolution: WR-subphases eWNL phase mainly affected Transitional phase introduced, H+He burning (right) Minimum mass is lowered by rotation Dependent on Z WR-subphases Tim van Werkhoven

  15. Stellar evolution: Observation Comparison with observational results Tim van Werkhoven

  16. Stellar evolution: Observation Comparison with observational results Tim van Werkhoven

  17. Rotation of stars improves models Rotation is a key ingredient for stellar evolution Opens new ways to interesting questions γ-ray bursts Supernovea Ring nebulae Pulsar rotation Stellar evolution: Conclusion Tim van Werkhoven

  18. Meynet, G. & Maeder, A., 2003, A&A 404, p. 975-990 Meynet, G. & Maeder, A., 2000, A&A 361, p. 101-120 Stellar evolution: References Tim van Werkhoven

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