Observations with MOST Pulsations in Wolf-Rayet stars : André-Nicolas Chené (NRC/HIA/CGO) Anthony...

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


Time series Fourier spectrum



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



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


QuickTime™ and a decompressor

are needed to see this picture.

























WR124WR124







comp1

comp2









comp2

Periodogram : WR 124Periodogram : WR 124

Periodogram : WR 124Periodogram : WR 124



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)






WR124(WN8h)

WR123 (WN8)

WR 110WR 110

• WN5-6 (single)– Light-curve

• WN5-6 (single)– Light-curve

QuickTime™ et undécompresseur

sont requis pour visionner cette image.

QuickTime™ et undécompresseur

sont requis pour visionner cette image.





(Chené et al. 2010)

1%


Binary?: Mcomp<3M if i>20º

Binary?: Mcomp<3M if i>20º






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

QuickTime™ and aTIFF (LZW) decompressor


Cranmer & Owocki (1996)




QuickTime™ and aTIFF (LZW) decompressor


Morel et al. (1997)

WR6HeII4686

Cranmer & Owocki (1996)












WR 1(Chené & St-Louis 2010)

WR 134(Morel et al.1999)

WR 6(Morel et al.1997)







WR 1

WR 110

WR 6


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)

Observations with MOST Pulsations in Wolf-Rayet stars : André-Nicolas Chené (NRC/HIA/CGO) Anthony...

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