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

Wolf-Rayet stars Hot and dense wind WN and WC Hot and dense wind WN and WC He II N III C III C IV WN WC

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

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: 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?)

Strange-Mode Pulsations Glatzel –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…). Glatzel –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…).

Previous results with MOST Time series Fourier spectrum

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

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

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

Cleaning the Light Curve : WR 124

WR124 comp1 comp2

Cleaning the Light Curve : WR 124 comp2

Periodogram : WR 124

0.29 c/d 0.71 c/d P = 1.41 d, 3.45 d

Spectroscopy : WR 124 EW, skewness & Kurtosis Binary?: K=5 km/s M comp 10º EW, skewness & Kurtosis Binary?: K=5 km/s M comp 10º (Moffat et al. 2010)

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

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

Spectroscopy : WR 110 Binary?: M comp 20º Binary?: M comp 20º (Chené et al. 2010)

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

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

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

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

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

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