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