A&A 478, 443-452 (2008)
VLA and Effelsberg observations of the interstellar medium around the runaway star WR 124S. Cichowolski1, 2, S. Pineault2, E. M. Arnal3, 4, and C. E. Cappa3, 4
1 Instituto de Astronomía y Física del Espacio (IAFE), CC67, Suc.28, 1428 Buenos Aires, Argentina
2 Département de Physique and Observatoire du Mont Mégantic, Université Laval, Ste-Foy, Québec, G1K 7P4, Canada
3 Instituto Argentino de Radioastronomía, C.C.5, 1894 Villa Elisa, Argentina
4 Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, 1900 La Plata, Argentina
(Received 23 July 2007 / Accepted 22 October 2007 )
Aims.We present very large array (VLA) and Effelsberg radio continuum and 21 cm line observations of the interstellar medium (ISM) surrounding the runaway star WR 124 and the nebula M 1-67. The H I data have been used to investigate the effects that a star with a strong stellar wind and a high peculiar velocity has on the ISM.
Methods.The VLA 21 cm H I observations were combined with single-dish Effelsberg observations to produce a series of H I images sensitive to all angular scales from the VLA resolution limit ( ) up to the primary field of individual VLA antennae (FWHM = 36). MSX and IRIS images were used to analyze the infrared emission around the star. Because the star is highly supersonic with respect to its local ISM, the observed H I distribution around the star is interpreted in terms of a simple bow shock model.
Results.The analysis of the H I data reveals the presence of a cavity centered on the star at an LSR velocity of 60 , consistent with a distance estimate of 5 kpc for WR 124. A second H I cavity is observed located 10 to the north of the stellar position, consistent with the direction of motion of WR 124. The VLA continuum image at 8.5 GHz shows a remarkable resemblance to the optical images. All available radio continuum data suggest a purely thermal spectrum for the nebula. The MSX and IRIS infrared data show a changing morphology with wavelength. The dust temperature deduced from the infrared luminosities is in agreement with previous observations of bow shocks.
Key words: ISM: bubbles -- ISM: individual objects: WR 124 -- stars: Wolf-Rayet -- ISM: H II regions
© ESO 2008