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Pulsations in Wolf-Rayet stars :

Pulsations in Wolf-Rayet stars :. Observations with MOST. André-Nicolas Chené (NRC/HIA/CGO) Anthony F. J. Moffat (Université de Montréal). Wolf-Rayet stars. Hot and dense wind WN and WC. WN. He II. N III. He II. He II. WC. C III. C IV. 25 to 40 M . O. RSG/LBV. WN. SN.

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Pulsations in Wolf-Rayet stars :

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  1. Pulsations in Wolf-Rayet stars : Observations with MOST André-Nicolas Chené (NRC/HIA/CGO) Anthony F. J. Moffat (Université de Montréal)

  2. Wolf-Rayet stars • Hot and dense wind • WN and WC WN HeII NIII HeII HeII WC CIII CIV

  3. 25 to 40 M O RSG/LBV WN SN 40 to 75 M O LBV WN → WC SN more than 75 M O WNha → LBV → WN → WC SN Evolution of massive stars

  4. Why observe WR star? • WR = epitome of hot stars with strong, stable winds • significant contributors to the ecology of the Universe • look for pulsations to (help) drive the winds: Momentum problem: [dM/dt v] / [L/c] < 1 for O stars (~OK), up to 10+ for WR (OK?)

  5. Strange-Mode Pulsations • Glatzel 1993-99-08 • Stars with a high L/M, where radiation pressure domines. • The most violent SMPs are expected in Wolf-Rayet stars. • Opacity bump due to iron. • Periods of a few minutes or hours are expected (but, finally, maybe days…).

  6. Previous results with MOST Fourier spectrum Time series

  7. WR103 WR123 Previous results with MOST Lines ~ 10% of broadband flux & vary relatively little • obs’d photometric variability must be related to pulsations of the stellar core! • delayed reaction of wind (lines) triggered by superposition of pulsation events

  8. Previous results with MOST  Stochastic clumps have no effect on period detection (Moffat et al. 2008)

  9. WR 124 • WN8(h) • WN8 stars are peculiar: 1) single, 2) high proper motion, 3) far from galactic plane, 4) mostly isolated and 5) very variable

  10. Cleaning the Light Curve : WR 124

  11. Cleaning the Light Curve : WR 124 comp1 WR124 comp2

  12. Cleaning the Light Curve : WR 124 comp2

  13. Periodogram : WR 124

  14. 0.71 c/d 0.29 c/d Periodogram : WR 124 P = 1.41 d, 3.45 d

  15. Spectroscopy : WR 124 • EW, skewness & Kurtosis Binary?: K=5 km/s Mcomp<2M if i>10º (Moffat et al. 2010)

  16. Spectroscopy : WR 124 WR123 (WN8) WR124 (WN8h)

  17. 1% WR 110 • WN5-6 (single) • Light-curve (Chené et al. 2010)

  18. Spectroscopy : WR 110 Binary?: Mcomp<3M if i>20º (Chené et al. 2010)

  19. Spots? : WR 110 m f Lamontagne et al. (1996) m f

  20. Spots+CIRs? : WR 110 Cranmer & Owocki (1996)

  21. Spots+CIRs? : WR 110 WR6 HeII4686 Cranmer & Owocki (1996) Morel et al. (1997)

  22. Spots+CIRs? : WR 110 WR 1 (Chené & St-Louis 2010) WR 1 WR 134 (Morel et al. 1999) WR 110 WR 6 (Morel et al. 1997) WR 6 (Chené et al. 2010)

  23. Origin of CIRs Magnetic wind or Pulsations confinement • (R. Townsend, A. Ud-Doula)

  24. The END Thank you very much André-Nicolas Chené (NRC/HIA/CGO) Anthony F. J. Moffat (Université de Montréal)

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