Post on 05-Feb-2016
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Observations with MOST
Observations with MOST
Pulsations in Wolf-Rayet
stars :
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 starsWolf-Rayet stars
• Hot and dense wind• WN and WC
• Hot and dense wind• WN and WC
HeII
HeIIHeII
NIII
CIII
CIV
WN
WC
Evolution of massive stars
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?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
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…).
• 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…).
Previous results with MOST
Previous results with MOST
Time series Fourier spectrum
Previous results with MOST
Previous results with MOST
Lines ~ 10% of broadband flux & vary relatively little
obs’d photometric variability must be related to pulsations of pulsations of the stellar corethe stellar core!!
delayed reaction of wind (lines) triggered by superposition of pulsation events
Lines ~ 10% of broadband flux & vary relatively little
obs’d photometric variability must be related to pulsations of pulsations of the stellar corethe stellar core!!
delayed reaction of wind (lines) triggered by superposition of pulsation events
WR103
WR123
Previous results with MOST
Previous results with MOST
Stochastic clumps have no effect on period detection
(Moffat et al. 2008)
WR 124WR 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
Cleaning the Light Curve : WR 124
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Cleaning the Light Curve : WR 124
Cleaning the Light Curve : WR 124
WR124WR124
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comp1
comp2
Cleaning the Light Curve : WR 124
Cleaning the Light Curve : WR 124
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comp2
Periodogram : WR 124Periodogram : WR 124
Periodogram : WR 124Periodogram : WR 124
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0.29 c/d
0.71 c/d
P = 1.41 d, 3.45 dP = 1.41 d, 3.45 d
WR124. Levels [4.61/5.99/9.21/10.6] correspond to [90/95/99/99.5]% confidence
Period [days]
0 5 10 15 20 25 30
2
4
6
8
0 5 10 15 20 25 30-0.1
-0.05
0
0.05
0.1
HJD-2451545.0
Δ m
2 4 6 8 10 12 14 16 18
Spectroscopy : WR 124Spectroscopy : WR 124
• EW, skewness & Kurtosis
Binary?:
K=5 km/s Mcomp<2M if
i>10º
• EW, skewness & Kurtosis
Binary?:
K=5 km/s Mcomp<2M if
i>10º(Moffat et al. 2010)
Spectroscopy : WR 124Spectroscopy : WR 124
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WR124(WN8h)
WR123 (WN8)
WR 110WR 110
• WN5-6 (single)– Light-curve
• WN5-6 (single)– Light-curve
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(Chené et al. 2010)
1%
Spectroscopy : WR 110Spectroscopy : WR 110
Binary?: Mcomp<3M if i>20º
Binary?: Mcomp<3M if i>20º
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(Chené et al. 2010)
Spots? : WR 110Spots? : WR 110
€
Δm∝−2.5log(1+ γ sinicos2πφ e−τ )
€
where τ = dτz= z0
∞
∫ = k d za( ) r2 1− R*
r( )β ⎡
⎣ ⎢ ⎤ ⎦ ⎥
−1
z= z0
∞
∫
Lamontagne et al. (1996)
Δm
Δm
Spots+CIRs? : WR 110Spots+CIRs? : WR 110
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Cranmer & Owocki (1996)
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Spots+CIRs? : WR 110Spots+CIRs? : WR 110
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Morel et al. (1997)
WR6HeII4686
Cranmer & Owocki (1996)
Spots+CIRs? : WR 110Spots+CIRs? : WR 110
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WR 1(Chené & St-Louis 2010)
WR 134(Morel et al.1999)
WR 6(Morel et al.1997)
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WR 1
WR 110
WR 6
(Chené et al. 2010)
Origin of CIRsOrigin of CIRs
Magnetic wind or Pulsations
confinement
Magnetic wind or Pulsations
confinement
(R. Townsend, A. Ud-Doula)
The ENDThe END
Thank you very much
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)