Tracing the wind structures in WR113
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Transcript of Tracing the wind structures in WR113
Tracing the wind structures in WR113
Alexandre David-Uraz (supervisor : Tony Moffat)
Université de Montréal
Outline
• Brief theoretical context
• Introduction to CV Ser
• Spectroscopy and orbit
• Lamontagne et al. fit
• MOST photometry
• Clumping and wind collision
• What’s next?
Brief theoretical context
• WR stars have a very high mass loss rate, typically
M ~ 10-5 M/year
• This rate cannot be explained by the star’s
luminosity alone
• A better understanding of the clumping
phenomenon is crucial in solving this problem
Introduction to CV Ser
• WR113 = CV Ser = HD168206 , SB2
• RA 18:19:07.36, DEC -11:37:59.2 (J2000)
• Galactic coordinates: l = 18.91º b = +1.75º
• Spectral types: WC8d + O8-9 IV
• v = 9.43 , b-v = +0.46
• P = 29.704 ± 0.002 d, e = 0 (?)
• Goal: use MOST to probe structures in the WR wind as its companion shines through it at different orbital positions
CV Ser – Field (DSS)
30'' x 30''
CV Ser – Optical spectroscopy (OMM)
CIII 5696
CIV 5806
HeI 5876
CIII 4650
HeII 4686
CV Ser – Orbit (Massey & Niemela, 1981)
CV Ser – Radial velocity plot (DAO)
CV Ser – Radial velocity plot (DAO + OMM)
Orbit of the O star?
“Shift and add” method
With the right orbit, it should be possible to separate each component’s individual spectrum with reasonable precision
Previous g-b photometry leading to i, dM/dt & MWR, MO (Lamontagne
et al. 1996)
CV Ser light curve (Lamontagne et al., 1996)
Hjellming & Hiltner (1963)
OMG!
CV Ser light curve (MOST)
Other light curves from the same field
Instrumental effects – HD 168112
Drift : (1.17±0.09)*10-4 mag/d
Instrumental effects – MY Ser
Drift : (5.4±0.1)*10-4 mag/d
Instrumental effects – CV Ser
Drift : (1.2±0.3)*10-4 mag/d Drift : (2.8±0.5)*10-4 mag/d
Lamontagne et al. fit applied to the MOST light curve
Lamontagne et al. fit “applied” to the other eclipse...
Random variations due to clumping?
Spectroscopic signs of clumping
How do the clumps affect the light curve? (an artist’s vision)
WR
Vers l’observateur
O
O
OPhase ~ 0.5
Phase ~ 0.25
Phase ~ 0
Wind collision (Bartzakos et al. 2001)
Lührs model
Excess emission (CIII 5696) in a WC4 + O9 binary
Excess emission in CV Ser (CIII 5696)
What’s next?
• Fourier analysis Fourier analysis in order to find pulsations in the star or its wind
• Wavelet analysisWavelet analysis in order to find random variations random variations due to the clumping
• Linking these variations to spectroscopic changes spectroscopic changes
• Establishing the phase dependancy the phase dependancy of these variations
• Putting together a model of the clumping phenomenonPutting together a model of the clumping phenomenon
• A new observation campaign new observation campaign is scheduled for June/July 2010, both on the MOST space telescope and the spectrometer at OMM