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Astron. Astrophys. 331, 949-958 (1998)

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Wolf-Rayet stars and O-star runaways with HIPPARCOS

I. Kinematics *

A.F.J. Moffat 1, S.V. Marchenko 1, W. Seggewiss 2, K.A. van der Hucht 3, H. Schrijver 3, B. Stenholm 4, I. Lundström 4, D.Y.A. Setia Gunawan 3, 5, W. Sutantyo 6, E.P.J. van den Heuvel 7, J.-P. De Cuyper 8 and A.E. Gómez 9

1 Département de Physique, Université de Montréal, C.P. 6128, Succ. "Centre-Ville", Montréal, QC, H3C 3J7, and Observatoire du mont Mégantic, Canada (e-mail: moffat,sergey@astro.umontreal.ca)
2 Universitäts-Sternwarte Bonn, Auf dem Hügel 71, D-53121 Bonn, Germany (e-mail: seggewis@astro.uni-bonn.de)
3 Space Research Organization Netherlands, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands (e-mail: k.vanderhucht,j.schrijver,diah@sron.ruu.nl)
4 Lund Observatory, P.O. Box 43, S-22100 Lund, Sweden (e-mail: bjorn,ingemar@astro.lu.se)
5 Kapteyn Astronomical Institute, P.O. Box 800, 9700 AV Groningen, The Netherlands
6 Observatorium Bosscha and Jurusan Astronomi, Institut Teknologi Bandung, Jalan Ganesha 10, Bandung 40132, Indonesia (e-mail: winardi@ibm.net)
7 Astronomical Institute "Anton Pannekoek", Kruislaan 403, 1098 SJ Amsterdam, The Netherlands (e-mail: edvdh@astro.uva.nl)
8 Koninklijke Sterrenwacht van Belgiï, Ringlaan 3, B-1180 Brussel, Belgium (e-mail: jean-pierre.decuyper@oma.be)
9 Observatoire de Paris-Meudon, D.A.S.G.A.L., F-92195 Meudon Cedex, France (e-mail: anita@mehipa.obspm.fr)

Received 6 August 1997 / Accepted 16 October 1997


Reliable systemic radial velocities are almost impossible to secure for Wolf-Rayet stars, difficult for O stars. Therefore, to study the motions - both systematic in the Galaxy and peculiar - of these two related types of hot, luminous star, we have examined the Hipparcos proper motions of some 70 stars of each type. We find that (a) both groups follow Galactic rotation in the same way, (b) both have a similar fraction of "runaways", (c) mean kinetic ages based on displacement and motion away from the Galactic plane tend to slightly favour the cluster ejection over the the binary supernova hypothesis for their formation, and (d) those with significant peculiar supersonic motion relative to the ambient ISM, tend to form bow shocks in the direction of the motion.

Key words: astrometry – stars: kinematics – stars: early-type – stars: Wolf-Rayet – Galaxy: kinematics and dynamics

* Based on data from the ESA Hipparcos astrometry satellite. Table 1 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr ( or via http://cdsweb.u-strasbg.fr/Abstract.html

Send offprint requests to: A.F.J. Moffat

© European Southern Observatory (ESO) 1998

Online publication: March 3, 1998