VLA and Effelsberg Observations of the interstellar medium around the run away star WR 124

CICHOWOLSKI, S.; PINEAULT, S.; ARNAL,E.M.; CAPPA,C.E.

ASTRONOMY AND ASTROPHYSICS

Año: 2007 vol. 478 p. 443 - 452

0004-6361

We present VLA and Effelsberg radio continuum and 21 cm HI lineobservations of the ISM surrounding the runaway star WR 124 and thenebula M 1-67.  The VLA continuum data at 8.5 GHz (3.6 cm) providethe highest resolution (~ 8 ") radio image of this nebula todate and show a remarkable resemblance to the (much higher resolution)optical images.  All available radio continuum data suggest a purelythermal spectrum for the nebula.  Contrary to many ring nebulaedetected around other WR stars, the VLA radio continuum image shows no obvious correlation with images obtained in the infrared.  The VLA 21cm HI observations were combined with single-dish Effelsbergobservations to produce a series of HI images sensitive to allangular scales from the VLA resolution limit (~46") up tothe primary field of individual VLA antennae (FWHM = 3').  A cavitycentered on the star is observed in HI at an LSR velocity of  ~60 kms, consistent with a distance estimate of 5 kpc forWR 124. The fact that the star is highly supersonic with respect toits local interstellar medium allows us to interpret the HIdistribution around the star in terms of a bow shock model.