EDP Sciences
Free access
Volume 414, Number 1, January IV 2004
Page(s) 203 - 209
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20031620

A&A 414, 203-209 (2004)
DOI: 10.1051/0004-6361:20031620

An Effelsberg HI study of the ISM around WR 126, WR 154 and WR 155

S. Cichowolski1 and E. M. Arnal1, 2

1  Instituto Argentino de Radioastronomía, CC # 5, 1894 Villa Elisa, Argentina
    e-mail: silvina@iar.unlp.edu.ar (Fellowship from CONICET, Argentina.)
2  Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional La Plata, 1900 La Plata, Argentina
    e-mail: arnal@iar.unlp.edu.ar (Member of Carrera del Investigador Científico, CONICET, Argentina.)

(Received 5 May 2003 / Accepted 22 August 2003 )

The neutral hydrogen distribution has been studied in the direction of three Galactic Wolf-Rayet (WR) stars using the 100 m Effelsberg radio telescope. Cavities in the HI distribution, regions of low HI emissivity, are observed over a 8-9  $\rm km\,s^{-1}$ velocity range for WR 126 ( $\equiv$ST 2), WR 154 ( $\equiv$HD 213049) and WR 155 ( $\equiv$HD 214419). These minima are interpreted as the observable 21-cm HI line counterpart of interstellar bubbles created by the winds of the WR stars and their progenitors. The HI cavities are elongated structures depicting an axial ratio ranging from 1.3 (WR 155) to 3 (WR 126). The WR stars are always eccentric with respect to either the geometric centre of the HI cavity or the absolute minimum inside it. This offset ranges from 50% to 80% of the HI hole's minor axis. The major axis of these structures range from 13 (WR 155) to 27 pc (WR 126), while the missing HI mass amounts to 45-50  $M_{\odot}$ (WR 126), 60  $M_{\odot}$ (WR 155) and 85  $M_{\odot}$ (WR 154).

Key words: ISM: bubbles -- stars: Wolf-Rayet -- stars: individual: WR 126, WR 154, WR 155

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© ESO 2004