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Turbulent outflows from [WC] nuclei

Published online by Cambridge University Press:  25 May 2016

Y. Grosdidier
Affiliation:
1Université de Montréal 2Observatoire de Strasbourg 3Observatoire du mont Mégantic
A. Acker
Affiliation:
2Observatoire de Strasbourg
A.F.J. Moffat
Affiliation:
1Université de Montréal 3Observatoire du mont Mégantic
O. Chesneau
Affiliation:
2Observatoire de Strasbourg
T. Dimeo
Affiliation:
2Observatoire de Strasbourg

Extract

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In the framework of the extensive study of [WC]-type nuclei of planetary nebulae undertaken since 1993 by Acker and collaborators, we report wind fluctuations for the two brightest late-type [WC] stars in the sky, observed at Observatoire de Haute-Provence (OHP, France) and Observatoire du mont Mégantic (OMM, Canada). In particular we confirm Balick et al.'s (1996, AJ, 111, 834) CIIIλ5696 line profile variations for the [WC8] nucleus of NGC 40. Moving features seen on the top of this line are interpreted as outflowing “blobs” which are accelerated in the WR wind. Kinematic parameters have been derived and compared to those observed for massive WR stars. This will be discussed in a forthcoming paper (Grosdidier et al., 1996, in preparation). Assuming the average motion of the blobs reflects the global wind expansion and adopting the ad hoc β velocity law, we find that the exponent β must be larger than 3 in order to fit the measured radial accelerations (up to ∼ 0.08 km s–2). Evidence for clumping in the wind of the [WC9] nucleus BD+30°3639 is shown for the first time and presented in Acker et al. (1996, A&ALetters, in press). In contrast to NGC 40, the clumps in this star show very low acceleration.

Type
III. Central Stars
Copyright
Copyright © Kluwer 1997