A giant bipolar shell around the WO star in the galaxy IC 1613: Structure and kinematics

Observations of the nebula associated with the WO star in the galaxy IC 161 3 are presented. The observations were carried out with a scanning Fabry-Pe rot interferometer in H alpha using the 6-m Special Astrophysical Observato ry telescope; narrow-band H alpha and [O III] images were obtained with the 4-m KPNO telescope (USA). The monochromatic H alpha image clearly reveals a giant bipolar shell structure outside the bright nebula S3. The sizes of the southeastern and northwestern shells are 112 x 77 and (186-192) x (214- 224) pc, respectively. We have studied the object's kinematics for the firs t time and found evidence for expansion of both shells. The expansion veloc ities of the southeastern and northwestern shells exceed 50 and 70 km s(-1) , respectively. We revealed a filamentary structure of the shells and sever al compact features in the S3 core. A scenario is proposed for the formatio n of the giant bipolar structure by the stellar wind from the central WO st ar located at the boundary of a "supercavity" in the galaxy's H I distribut ion. (C) 2000 MAIK "Nauka/Interperiodica".